Author: John Porter

John Porter is a horticulturalist located in Omaha, NE. He is a former extension educator with UNL Extension and county agent with WVU extension. In addition to using his horticulture and extension skills in his home garden, he is a sometimes garden writer and lecturer, a trial judge for All-America Selections, and mentor for local school horticulture and agriculture programs.

Falling forward: Time to plan and plant the fall veggie garden

While most of the country is in the middle of a heat wave and the mercury is creeping past 100F on many thermometers, lets do a little exercise to help you feel cool as a cucumber (though not straight out of the garden, those cucumbers would likely be hot).  I want you to think about a crisp September morning.  You’re out walking through your vegetable garden and you stop to appreciate a big, emerald green head of broccoli.  Just a few feet away, stalks of Brussels sprouts, those miniscule cabbages that have somehow overcome years of revulsion to become sexy and desirable (they must have a good agent) shoot up like skyscrapers around the rest of the plants.  Lush lettuce fills in a bed nearby, and some cucumbers and beans that you planted late are looking as fresh as a newborn chick. 

Sounds beautiful, doesn’t it?  Well I’m here to tell you that you can actually make this a reality.  You can have a super productive garden this fall, and for most areas of the country the time to start planning and planting is now.  Right now, when a cool refreshing fall morning seems as far away as a trip to the moon.  Of course, the exact timelines and planting schedules differ by region due to the length of growing season, but most places in the US (and the northern hemisphere) can start thinking now about planting crops for the fall.  For exact timing in your area, you may want to connect with your local extension system for gardening guides. 

While many experienced gardeners may know this and practice fall garden planting, there’s a lot of people out there who have yet to have the pleasure.  And given the huge number of first time (or first time in a long time) gardeners, these garden basics might be helpful to get the most out of those pandemic plantings. 

In fact, fall is one of the best times of the year to garden.  Aside from cooler temperatures making it more pleasant to garden, there’s often less pressure from diseases and insects to ruin crops.  In addition, many of those cool season crops, like the ones I mentioned above, actually are more productive in the fall than if planted in the spring.  Even though they get a hot start in mid- to late- summer, the cooling temperatures of fall around the time many of the crops come into maturity extends the harvest period and improves overall quality of the produce.  You also have the benefit of removing some of those spent and diseased warm season plants and swapping them out for something fresh and new– a garden revival of sorts. 

Swiss chard and leafy greens are great additions to the fall garden

Unfortunately, since fall vegetable gardening isn’t as widespread as planting summer gardens, plants and seeds can often be hard to find when it is actually time to plant (so planning ahead is helpful).  Mid-summer is usually the time for most regions to start seeds for those slower growing cool season crops like broccoli, cabbage, cauliflower, and their kin. They can be started indoors, but the need to do so isn’t as great as it is for those warm season crops we start indoors in late winter.  You can start them in pots/flats outdoors as long as you have somewhere that isn’t so hot and sunny that they’ll be continually drying out (some shade would help).  They should be ready to transplant by late summer.  You can skip the seed starting/transplanting if you want to try direct seeding into the garden, but as they say “your mileage may vary”. 

Some of the fast maturing warm season (frost tender) crops are also good candidates for a mid-summer planting as a way to refresh the garden if you have space for it.  Beans are a good candidate for late-summer planting, but you’ll need to make sure they are a fast-maturing variety (there’s a wide range of maturity times in beans). Bush beans are usually the quicker growers. Pole beans and lima beans usually take a longer period, so those don’t do as well later in the season for places that have frost and freezes. 

It is also a possibility to squeeze in a late crop of cucumbers or summer squash as well. This can be good if your cukes and squash succumb to disease, squash vine borers or cucumber beetles. Planting late can often mean that you are missing the primetime for specific pests. For example, squash vine borer adults actively lay eggs in the early season but largely disappear later on.  A late planting means you could miss them entirely. 

Fall is the best time to grow leafy green vegetables.  Lettuce, which does not fare well in the summer, thrives in the cooling temperatures of the fall.  Other leafy greens, such as chard, spinach, and kale are also winners in the fall garden.  Many of the root vegetables, such as turnips, carrots, beets, and radishes are also part of the fall garden revival.  You’ll want to wait until temperatures have chilled a little to get these started, but not so late that the season ends before you get good growth. 

You gotta know when to sow ‘em

The key to fall planting is to know how many days it takes for the crop to mature. Check out the seed package or the plant tag — there should be a time to maturity on there. Just count backward from the first frost date. Be sure to add a few weeks to account for slower growing in cool weather and to allow for a reasonable harvest time.

For example, if I wanted to plant a late crop of beans, I might select the cultivar ‘Contender’ which matures in about 55 days.  I want to add at least a few weeks onto that for maturity and harvest time, so lets say I need 75 days (I can go shorter if I want to accept the risk of an early frost).  Let’s also say that my first frost date in the fall is October 20.  Counting back 75 days from October 20, I get August 6 – I should plant my beans no later than that date to get a harvest.

Most of the cool season crops can tolerate a frost (and some even a freeze) so their growth dates can extend beyond the first frost date.  You’ll just want to have them mostly grown and close to maturity before it gets cold enough to stop their growth.  I covered frost and freezes and which crops can survive those cold temps in this previous GP article. 

You can give yourself a little more time if you plan on incorporating a season extension practice in the garden. Using a row cover or constructing a low tunnel can give you several more weeks of growing time. It can be possible to enjoy a fresh tomato or green beans straight from the garden on the Thanksgiving table, or some fresh broccoli or kale at Christmas even in some of our colder regions. But it all starts with a little planning in the heat of summer.

And if you choose not to plant a fall crop, I would suggest using a cover crop in garden beds as you remove this year’s plants.  A cover crop will help keep weeds to a minimum and preserve soil structure and nutrients through the winter.  Winter wheat, rye, and crimson clover are good winter cover crops.  Next spring you just cut them down and till them in if you’re not practicing no-till (and you should be if at all possible). For annual cover crops, you can usually cut them down or break them over and leave them in place as a mulch. You can also pull them up and compost them to add directly back to the garden, especially if (since it is hard to till or mow in a raised bed).  This GP article is an oldie but goodie for using cover crops in the vegetable garden. 

Water Wise Gardening: Conserving and Irrigating Responsibly

While we can’t ever control or even predict the weather, in most places it is important to have a plan on how to deliver water to our home gardens during the hot, dry months of the summer.  Aside from reducing water need through some good management practices, delivering water in an efficient and sustainable way is important when planning and planting our home gardens. 

When there is scarcity, it is necessary to conserve. Several years I got to see scarcity in person on a sustainable agriculture tour of New Mexico.  Farmers in New Mexico have only limited access to water from irrigation canals, to flood irrigate their fields, or even wells for drip irrigation.

This severe lack of water got me thinking about how much we take water for granted in our own gardens.  We often apply as much as we want or need in an inefficient manner (using sprinklers, sprayers, etc.) because we think it will always be there when we turn on the tap. 

Where I’m located in Nebraska we are also blessed to have water falling from the sky. Sometimes there’s too much, and at others there’s not enough. But that’s much better than in some places – I visited some parts of New Mexico on a farm tour where they get seven inches of rainfall in a normal year. Seven.  Total.

Thinking about conserving what water we have means that we are good stewards and are ready for when issues do arise. And let’s face it, there are some times in the summer that are dry where water conservation will help reduce using water, which can also save money.

When we talk about conserving water, there are two ways to go about it. First, look for ways to reduce the need for water. Then, look at ways to reduce water waste and usage whenever you need to use water on your lawn, landscape or garden.

Reducing the need for water

During dry times, it can be necessary to provide water to the garden to keep it growing healthfully along. However, there are many ways to reduce water loss or increase the amount that stays in the soil around the plants.

Mulching not only reduces weeds, but also helps hold moisture in the soil. Having one to two inches of mulch on landscape beds can reduce evaporation from the soil and decrease the amount of water you need. Newly planted trees should be mulched for the first few years to help hold moisture in the root zone as well.

Mulching is also important in the vegetable garden. Using straw or shredded newspaper are simple ways to conserve moisture, beat weeds and even reduce diseases. Note that this is shredded newspaper used on top of the soil for a mulch, not whole sheets applied below another mulch or on top of the ground.  That process is called “sheet mulching” and we typically don’t recommend it here at the GPs because it limits air movement into the soil and can disrupt the soil microbiome. Stick only to shredded newspaper as a top dressing. (See the bottom of the article for journal articles discussing paper and straw mulches).

Shredded newspaper in my tomato bed. There are 2ft woodchip mulch walkways between 4ft wide beds.

You can use woodchip mulch in the vegetable garden, but it can be difficult to manage when you are frequently planting, replanting, or harvesting crops.  If you accidentally incorporate it into the soil, it can tie up nitrogen available to plants and cause deficiencies.  As long as you are good at keeping it on the surface, it isn’t as much of an issue.

Large scale gardens or farms make use of black plastic as mulches to do much the same thing. Plastic mulches are typically beyond the scale needed for home vegetable gardens and have their own set of drawbacks such as limiting water and air movement, but for those struggling with difficult weeds or with issues limiting manual removal (disability, limited movement, etc) it may be explored for smaller scale production. There are now even biodegradable plastic and paper mulches available. Use of these does require drip irrigation beneath the mulch, as rain cannot penetrate to the root zone. With the issues associated with them, plastic mulches would be considered a last resort for all but the largest home vegetable gardens, and many of my GP colleagues recommend against them for all home garden situations – but they can have their very limited place in the home garden toolbox.  And we definitely recommend against the use of plastics and landscape fabrics in ornamental beds and landscapes.   

Choose plants that require less water. There are many plants available that have lower water requirements. Ornamental grasses, Liatris (blazing star), Kniphofia (red hot poker) and sunflowers come to mind. Most native plants are commonly thought to have lower water requirements, but this isn’t always the case and natives may not thrive in altered ecosystems (urban settings or even managed landscapes). Most bulbs also are water efficient and do not require extra watering, as are most culinary herbs.

Mowing less often in the hot and dry summer also can conserve water if you are one who waters the lawn. I’m not a big fan of watering lawns, since it is such a large water usage, but I know there are those who prefer to have their lawns lush and green at all times. Instead, when the summer gets hot and dry, leaving the grass on the taller side can help it stay green even without water. Many of the grasses we grow here are cool-season and go semi-dormant in the heat. Stopping mowing when the heat starts slows down growth and the need for water.

Irrigating Efficiently with Drip

When it comes to getting water to the garden, there are definitely more efficient ways to make it happen.

Unfortunately, the most common method — using sprinklers — is also the least efficient. It is hard to direct the water to the right place, and during periods of high heat evaporation takes up much more water than you think. But there are ways to get water to your thirsty plants without running up the water bill.

Drip irrigation is probably amongst the most efficient and sustainable ways to water your landscape or vegetable garden. This method allows you to apply water directly to plants in a controlled manner, rather than spraying an entire area with water.  Also, since the water is applied directly to the ground rather than sprayed through the hot summer air, the water is much less likely to evaporate. 

Drip irrigation tubing. Each drip opening emits on this version emits 1 gallon of water per hour.

There are a few different types of drip irrigation systems available.  Probably the easiest to install is a drip tape system.  This is a deflated tape that already has water-emitting slits cut into it.  While each slit applies a precise amount of water over a given time period, the pre-determined regular placement of the slits makes this system better for plants grown in rows, like vegetables, rather than landscapes where plants are of differing sizes and spacing.  And while it can be used for vegetable gardens, probably the easiest system for a landscape would be one where there are tubes you can cut to various lengths and insert controlled drip emitters at customized locations.  Another use for this type of drip irrigation could be for containers on a porch or deck – you can easily run the tubing out of sight along a bannister or railing and direct individual emitters to individual containers.

It all sounds complicated, and larger systems can be, but there are small and simple kits you can easily find at many garden centers or online retailers available for home gardeners to install their own within a matter of hours. You will need to have some skill at reading directions to install them, but the process is pretty simple. 

For information on setting up drip irrigation for your home garden, check out these great resources from Extension institutions across the country:

Drip Irrigation for Home Gardens

Building and Operating a Home Garden Irrigation System

DRIP: Watering the Home Garden

Soaker hoses are a similar concept to drip irrigation, but instead of small drips these hoses just emit water all along the hose. Still better than sprinklers, these hoses are quite a bit less efficient than drip, since you can’t direct the water exactly where you want it.  They are also easy to apply too-much water to an area since they can emit large volumes. Installation is pretty simple, though, since you just lay the hose down where you want it.

One great benefit of both drip irrigation and soaker hoses is the application of automation.  Using a timer can make it easy to keep the garden watered through the season. Timers can be as simple as a dial to manually run the irrigation for a specified time or fully automatic to run the irrigation for various lengths of time on different days of the week.  Some more advanced timers also have rain sensors or soil probes to reduce or avoid running when rain makes watering unnecessary (if you don’t have a sensor, remember to stop automatic running until the soil has dried).  And in today’s emerging technology, there are also timers or flow controls that can be automated or controlled from a phone app.  The timer that I’m now using at home connects to my Wi-fi, and in addition to allowing me to control and observe the watering status from anywhere in the world, connects to local weather data to automatically set a “smart watering” schedule taking into account rainfall, temperature, wind speed, and other factors. 

My fancy water timer.

Another effective way of providing water to your garden is through water catchment.  Water catchment is just a fancy way of saying that you use a rain barrel. Here you are collecting rain runoff to use in place of water from the tap. There are some ultra-low-flow drip irrigation systems that you can use with rain barrels (if they are raised high enough to get water pressure), but this use is usually for watering by hand. For larger gardens, the large IBC totes that hold 200 or more gallons can make good water catchment barrels.  Just make sure that if you are using them (or any other barrel) for fruit or vegetable production that they are made of food-safe plastic and their previous contents were also food safe.  (Check out our guide on Building a Rain Barrel)

Selected references:

Comparisons of shredded newspaper and wheat straw as crop mulches

Soil Temperature, Soil Moisture, Weed Control, and Tomato (Lycopersicon esculentum) Response to Mulching

Newspaper Mulches for Suppressing Weeds for Organic High-tunnel Cucumber Production

Viral Vegetables? Growing (and Buying) Produce in the age of COVID-19 (and reducing fear with facts)

Now that much of the world’s attention is focused on limiting the spread of pathogens, well one pathogen, it seems like a good time to talk about some of the questions or concerns we’ve seen regarding vegetable gardens, community gardens, and farmers markets.  It’s a good time to talk about some of the practices that we should be doing to prevent other human pathogens from handling produce, like E. coli and Salmonella, and how those might fit into preventing the spread of COVID-19. 

First things first

First off, we have to remember that SARS-CoV-2, which is the virus that causes COVID-19, is not a food borne illness.  I repeat: COVID-19 IS NOT A FOOD BORNE ILLNESS. This means that it is not spread through the consumption of contaminated food like E. coli and Salmonella.  I’ve seen many instances of people spreading fear about food online, with many suggesting using soap or bleach on food to minimize risk.  Those steps are both unnecessary an actually pose a poisoning risk.  There is currently no evidence to suggest that COVID-19 is transmittable by food or food packaging.

The risk from food (which is considered minimal by experts) is from cross-contamination from food or packaging onto hands or onto surfaces that are then touched by hands.  The virus would then have to go from a persons hand to mucous membranes in the respiratory system by something like touching your face or picking your…..well, we won’t go there.  The best defense against this isn’t necessarily sanitizing all the food you buy, but washing your hands after you handle it and sanitizing any surfaces that packaging or shopping bags touch. 

Factsheet: Is Coronavirus a concern on Fresh Produce?

But while we’re on the topic of pathogens and food safety, it’s a good time to talk about some general guidelines that can not only help stop that potential SARS-CoV-2 cross contamination but also food borne illness in general.

Minimizing the risk from produce even further

Whether you grow it in your own garden, buy it at a local farmers market, or purchase it at the grocery store, produce has a minimal risk when it comes to COVID-19. 

Factsheet: COVID-19 and Food Safety – Shopping and Handling Groceries

To minimize the very small risk of cross-contamination even further and (probably more importantly) to also reduce any risk from common food borne illnesses, proper washing of the produce should be practiced.  But do you know how to do that?  Maybe…and maybe not.  Here are some steps to help out. 

  1. Wash your hands. The most common pathway of contamination for produce is from human touch.
  2. You should use clean water that you would use for drinking (like out of the tap) and not use any bleach or soap. 
  3. Providing gentle friction with your hands or a produce brush or by rubbing the produce together is sufficient. 
  4. If you’re washing a lot of produce at once, say from a large harvest, and you’re using a tub full or sink full of water to wash multiple “loads” of produce, keep an eye on how dirty the water gets and refresh it when it gets discolored.  Remember that washing produce in a tub or sink of water can also present a cross-contamination issue where contaminated produce contaminates the water. 
  5. When in doubt, discard produce you may think is contaminated or wash it separately. 
  6. To reduce risk of cross-contamination, consider a “single pass” washing technique where you spray the produce with water and it doesn’t sit in water with other produce. 
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Food Safety in the Garden

There are a few things we can do in the garden to help stop the spread of human pathogens.  Most of them are common sense things that most people don’t even think about.  Devout GP readers may remember my little missive around this time last year about the food safety risks of using manure in the vegetable garden (See: The Scoop on Poop).  Beyond those musings on manure, though, gardeners can take some additional steps to reduce potential contamination.  Those are:

  • Wash your hands.  I know it sounds simple, and maybe even more so now that it has been drilled into our brains, but washing your hands before you garden is one of the best ways to reduce the spread of pathogens.  It is especially important to wash your hands before you harvest produce or handle harvested produce.
  • Use clean containers for collecting and storing produce.  Using harvest baskets, tubs, and totes is common, but the ones that are best in terms of food safety are those that can be washed and sanitized.  This is one tactic that many farmers are encouraged to use as well.  Plastic tubs, totes, trugs, and crates are probably best as they can withstand washing and the use of a sanitizer like bleach.  Wooden or woven baskets may be cute, but they’re harder to clean and can hold on to pathogens. 
  • Look for signs of wildlife in the garden.  Aside from eating more than their fair share of produce, wild animals can also present a food safety risk especially from their droppings.  Look for signs of animals in the garden and especially take note of any droppings.  Don’t harvest produce that has signs of droppings on them.  Many of the big produce recalls over the last decade have been a result of wild animals like birds or wild hogs. 
  • Keep pets out of the garden.  As much as you like to have Fluffy or Fido in the garden, they present a risk just like wild animals do. 
  • Wash produce using proper techniques (previously discussed).

Best practices for minimizing COVID-19 risks at Community Gardens (and Farmers Markets)

You can practice handwashing anywhere. You can buy portable hand washing stations or build this DIY Model. Plans: https://www.youngfarmers.org/fsma_resources/portable-handwashing-stations/

One other aspect of gardening that could provide some risks for the spread of COVID-19 are the more social aspects of gardening, such as community gardens.  I’ve had several local gardens reach out for best practices relating to minimizing risks in the garden – from handwashing stations to shared tool use.  Thankfully, NCSU Extension was quick on the draw with resources for lots of aspects of the food system in terms of reducing risks from COVID-19 and they graciously allowed other universities to distribute these resources.  Below are some links to the resources that would be helpful to gardeners:

COVID-19 FAQ for Community Gardens

And since some gardeners may sell at (or at least visit) farmers markets:

COVID-19 FAQ for Farmers Markets

Click here for all the resources developed by NCSU

Flowers for Barbara: Cultivating Hope in a Pandemic

Ever since humans started gardening and farming, the practice has had central importance in our lives. As we processed out of the agrarian age, some of us humans may have lost the connection to the importance of growing plants to our everyday lives. We rely on the growing of plants to feed us, to produce medicine, clothing, and shelter. We use plants to provide beauty in our landscapes and our homes. And perhaps one of the positives of the current pandemic is that many people are turning to plants as a way to assuage their fears. Being one of those extension people whose mission is to teach people gardening I’ve seen some of this first hand. But a phone call I received this week really drilled into my soul how important plants are not only for the food they provide, but also the way they effect our mental well-being.

Victory garden - Wikipedia
Victory Gardens Poster
Source: WikimediaCommons

As the last few weeks have unfolded, we’ve seen seed companies struggle to keep up with orders, garden center shelves empty of vegetable seeds and plants, and a general movement that what the National Garden Bureau is calling Victory Gardens 2.0. Many are saying that vegetable seeds are the new toilet paper. There are a few reasons that people are turning to gardening in a time of crisis. Gardening is seen by many as a grassroots way of ensuring food access. In addition, the ability to grow one’s own food not only produces said food but also provides a feeling of self-sufficiency for the gardener. The mere act of knowing that you have some sort of control over your access to food, because you can grow your own, provides a sense of calm. It helps ease some of the uncertainty of wondering if there will be produce at the grocery store or if you will have the financial stability to afford it. During the economic crisis of 2009, the National Gardening Association estimated that home food gardening (vegetables and fruit) increased by 19%. It might be too early to tell, but I suspect those numbers will be higher this year.


But lets get back to the phone call….
Gardening and plants also have a positive effect on mental-well being in a general sense. The act of gardening can produce a meditative like practice (unless you’re cursing at weeds or violently ripping out diseases plants – but those acts may provide catharsis). But research also shows us that just seeing nature can have a calming effect on our minds.

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Insult to injury: 6+ inches of snow after the frigid temperatures
Source: Scott Evans, UNL

This was so apparent in my recent call. I had received a voicemail from an elderly gentleman that asked for a call back as soon as possible so that I could talk to his wife (we’ll call her Barbara). I had time between back to back Zoom meetings, so I called. The gentleman answered and after I introduced myself he told me that Barbara had a question about flowers. After a few seconds, a frail, halting voice asked me if all the tulips and daffodils were dead. Over the previous few nights temps had dipped below the normal lows and many plants had seen some damage, including flowers of many early season bloomers.


I answered briefly that some of them were likely damaged, that the blooms would be killed but the plants would be OK. What happened next….I didn’t expect. Full on, gut-wrenching crying. The kind of sorrow that you can feel throughout your being. After a few seconds, between the gasping sobs, she uttered the words “I don’t think I can take it anymore. First we can’t see people. Now the flowers are gone.”


After the initial jolt, I tried to respond as I’ve been trained to do (we have luckily received training in mental health first aid to help clients who are in distress) – calm reassuring words, asking if she was OK, and providing positive affirmation that once the temperature warmed up there would be blooms again. Though she was so overwhelmed that she just said goodbye and hung up.


I was shocked. It took a few minutes for me to compose myself. I don’t often deal with clients where there is such an emotional response (hats off to my entomology colleagues who have to deal with telling people that they have bedbugs or that they might be suffering from delusory parasitosis). After I gathered my thoughts, I felt that I needed to call back – the emotional response was so strong that I wanted to make sure there wouldn’t be issues of self-harm or other effects.


In my return call, Barbara and I discussed that there would be more flowers once the weather warmed back up. We discussed our mutual love of plants and how they make us feel. She sees the flowers in the neighborhood when they leave their small apartment for errands and it makes her feel better. And even though there were still tears, both of us were in a much better place. Out of the blue, I asked if it was OK if I brought her flowers to enjoy until the weather warmed up. At first she was hesitant – she didn’t want to cause trouble. But after I assured her that making sure she had flowers would do me just as much good as it would her, she and her husband agreed. I told them that after I got done with my work for the day, I would find some flowers and drop them off on their doorstep.


I needed to make a (now infrequent) run to the store for necessities any way, so while I was shopping I picked up a potted plant at the grocery store (the one I thought would be easiest to care for). I went home and wrote a note, wrote down some simple directions, and delivered the flowers. As I walked away, I heard Barbara’s husband open the door and tell her that there was a surprise for her.


I have to say that I can totally understand this reaction that may seem excessive to some. Many people are dealing with the stress of the pandemic, some better than others. Here was one thing that was giving this lady enjoyment – seeing the flowers blooming when she is able to get out of the house. And that one enjoyment had been taken away by a late freeze. It drove home to me the fact that gardening and plants are essential for many. For the food that they can provide, both for nourishing our bodies and for nourishing our spirits. Plants are providing us hope for the future and calm for the present.

While I may never hear back from Barbara and her husband again, I can tell you that making that one connection through plants was definitely a boost for me. My wish is that those flowers give her hope for the future. A sense of calm knowing that one day things will return to normal, and the knowledge that one day soon the flowers will indeed bloom again.

Flowers for “Barbara”

Planting Prognostication: Understanding last frost and planting dates

Except for areas of the US that are more tropical like southern Florida or Hawai’i, most gardener’s planting schedules are set around winter weather and the possibility of frost or freeze.  And even for gardeners in those more tropical areas, planting sometimes needs to be planned to schedule around the extreme heat of summer.  Understanding these planting times can really lead to success or failure, especially for vegetable gardens, tender annuals, tropicals, and non-dormant perennials.  There are a few tools that help us understand weather patterns and predict critical temperatures for planting, namely the USDA Hardiness Zone map and the Average Last Frost/Freeze dates.  The USDA Hardiness Map shares data on what the average coldest temperature is, which is key for selecting perennial plants that you want to survive the winter.  However, to know when to plant we look at the average freeze and frost dates.  There seems to be a little bit of mystery, and even confusion, around the dates and how to interpret them, so let’s take a little time to understand them a little better.  And since my background is in vegetable production, I’ll share a bit more detail there in terms of plants – but you can translate the information to ornamentals, especially those that are frost tender pretty easily. 

Understanding Average Last Frost Date

What is the average last frost date and how is it figured?  The average last frost date is exactly what it says it is – the average date at which the probability of frost has diminished.  Just how diminished really depends on the source, so we’ll follow up with that in a bit.  The data is computed by NOAA (National Oceanographic and Atmospheric Administration) and the National Weather Service to determine the probability of temperatures relating to frost and freezes based on weather data for an area over the last 30 years.  They compute the likelihood of a light frost (36 F), frost/heavy frost (32 F), or freeze (28 F) at three different probability levels – 90% (the temperature is very likely to happen), 50% (the possibility is 50/50), or 10% (the temperature is unlikely).  This tool from NOAA provides a chart with probabilities for locations throughout each state.  

This data is typically collected and analyzed every ten years or so.  I’m not exactly sure when the last data was analyzed, but I did find some maps on the NWS referencing the period 1980/81- 2009/20 (below).  Therefore it is likely that new data will be released either this year or next year.

Temperature hardiness of common vegetables

Awareness of tolerance is especially important for vegetable crops, as the growing season and expected productivity of the plants.  The following chart is a general guideline, and your mileage may vary based on cultivar difference, microclimates, and other factors.  Also note that these temperatures are for both planting in spring and fall kill temperatures.  Some of the more tender plants, like tomatoes, may withstand colder temperatures when they’re mature so they may be less susceptible to frost at the end of the season vs. the beginning of the season. 

Season extension techniques, such as row covers can be used to protect tender plants in the spring and extend harvests in the fall.  Row covers can be selected by the degrees of protection they deliver.  For example, a row cover may offer 4 degrees of protection.  This allows the protected plant to withstand air temperatures 4 degrees colder that what it would unaided. For fall crops, note that plants may stop growing well before the kill temperature but will hang out in “stasis” until they are killed. The above NOAA chart provides probabilities for both spring and fall – allowing you to not only plan for spring planting but also for fall crops.  For scheduling fall crop planting dates, find your first frost date, count backwards the days to maturity (from the seed packet or tag), and add a few weeks for a harvest window and for the slowing growth as temperatures drop.

The Problem with Probability

These probabilities are based on past weather data, so keep in mind that these dates are used as a prediction not as a guarantee.  It is especially important to remember this as weather uncertainty increases with climate change.  Last frost could occur well before or even well after these predictive dates.  This also begs the question – which probability should you use?  Looking around at different sources, you might find sources that use either the 50% or 10% probability statistic, and there seems to be a bit of disagreement as to which one should be used.  Based on the data for my region, I’ve seen sources share both dates.  It really comes down to how much of a gamble you want to take or how much you want to push up harvest or maturity.  If you plant on the earlier 50% probability date you may end up having to cover the plants a few times to protect them from frost.  But each day that passes means that the chance of frost or freeze decreases.

Whenever I give a talk here at home in Omaha, I often ask my audience to guess what the average last frost date is for planting.  Invariably, the answer I get is Mother’s Day…which I guess works as a guidepost in general.  However, looking at the data (below), we can see that the 10% probability date for a 32 degree (killing) frost is May 4.  The light frost date is May 11 – plants may be damaged but not killed unless they’re very tender.  And the 50% probability date for a killing frost is actually April 21, which is the point where the probability of frost is 50% each day (and the probability shrinks each day.

Sometimes produce growers may opt to go early to get vegetables to market – which extends the sales season and allows them to charge a premium price if no other growers are selling.  Season extension techniques like high tunnels have also pushed back farm production dates.  As climate change makes weather more unpredictable, we may all be finding ways to alter the growing season as a norm rather than an exception.  Until then, we’ll rely on the data we have to make the best predictions.   

Sources:

https://www.canr.msu.edu/news/freeze_damage_in_fall_vegetables_identifying_and_preventing

http://www.gardening.cornell.edu/homegardening/scene0391.html

https://www.weather.gov/iwx/fallfrostinfo

https://www.ncdc.noaa.gov/cgi-bin/climatenormals/climatenormals.pl?directive=prod_select2&prodtype=CLIM2001&subrnum%2520to%2520Freeze/Frost%2520Data%2520from%2520the%2520U.S.%2520Climate%2520Normals

When Good Seeds Go Bad: How long can you store seeds?

Many gardeners, myself included, have that stash of old seed packets or saved seeds from garden seasons past, just waiting for the right time to be planted. They may be shoved in a drawer, a box, or in the fridge/freezer. Maybe you’re pulling some out of storage to start this spring – will they even germinate? Are those seeds good indefinitely? Do they ever expire? The answer to that really depends on what plant it is and how they are stored. While there isn’t a date where all the seeds go bad, they will eventually go bad over time. Why is this? And how can I make sure to use my seeds before they’re gone? Let’s find out!


Why Good Seeds Go Bad
While we think of seeds as perhaps inert, dormant, or in stasis they’re still very much alive and therefore are still undergoing processes like respiration, though at a much lower rate than a growing plant. During respiration, the seed (and plant within) are converting the stored sugars and starches in the endosperm to release energy. Once the germination process starts with the imbibition of water, the respiration rate increases drastically. A large amount of stored energy is needed to get through germination and sustain the seedling until it has its first set of true leaves and can photosynthesize on its own.

Seeds need to retain enough stored energy to sustain seedlings until they develop their first leaves and start photosynthesizing.

The shelf life of seeds is determined by the amount of energy that is stored, the amount used during storage, and the amount needed from germination to leaf development. This means that there’s a limit to how long a seed can stay in storage. After a while the seed loses viability if it doesn’t have enough energy stores to get it far enough along to photosynthesize on its own or to have that first burst of respiration at the initiation of germination. When searching for resources, keep in mind that viability refers to the ability of the seed to produce a robust seedling while germination refers to breaking of dormancy. The terms are inter-related, but the rates are not necessarily the same.

Some seeds have evolved to sit dormant for a long time, while others have a very short lifespan. It usually turns out that the seeds that last longest in storage are weeds that have evolved to wait long periods of time for an opportunity to germinate. Garden seeds tend to be on the shorter end of the storage time scale. A now 140-year old ongoing experiment at Michigan State University has given some interesting insight. In 1880, William Beal (one of the fathers of horticulture) buried 20 vials full of a variety of seeds (garden and weed) in secret locations around campus. The plan was to dig one up every 5 years and see what germinated. However, after the fist few rounds the cycle was bumped to 20 years. A vial was opened in 2000 and only one species, a weed, still germinated. This year is another germination year – we’ll have to wait and see if the mullein will germinate again this year.

How long will my seeds last?

Data from Nebraska Extension publication.

There are a few good sources that pull data from a variety of sources. The figure below lists some life expectancy times for common vegetable crops published by Nebraska Extension, using two common manuals on seeds as sources. You’ll also find some likes to other data, including average storage times for flowers, herbs, etc. in the references section (while we don’t typically promote commercial sites, the guide from Johnny’s Select Seeds has a good list of plants and has a variety of extension and academic sources listed). Like the MSU experiment, most of this research was done a while ago, but the data is still a good generalization. Most sources say that these time estimates are based on storage in optimal conditions. According to Johnny’s Select Seeds, “The actual storage life will depend upon the viability and moisture content of the seed when initially placed in storage, the specific variety, and the conditions of the storage environment”.

What are these “optimal” conditions? Generally the conditions are low humidity and low temperature. Low humidity ensures that the seed stays dry, avoiding potential initiation of germination. Low temperature reduces the respiration rate, slowing down usage of stored energy and increasing longevity. Optimal temperature for storage is below 42°F (15°C). Relative humidity should be between 20 and 40%.

The relationship between temperature and humidity seems to be inverse – meaning that as storage temperature goes lower, humidity can be higher and vice versa. However, storage times increase as both go down. Many sources state that seed longevity doubles for every one percent drop in humidity or five degree (F) drop in temperature. The relative humidity of the air affects the moisture level in the seeds. Germination usually starts at 25% moisture (and above). Ideal moisture levels for storage range between 8 and 12 percent and levels between 12 and 25 can lead to degradation of seeds, growth of fungi, etc. On the flip side, moisture levels below 5% can decrease vigor. Organizations like seed banks and germplasm centers that store seeds long term often will desiccate seeds to around 8% humidity to extend storage, but this isn’t usually needed for home gardeners.

Image result for seed vault
You don’t have to replicate conditions at the Global Seed Vault to have seed saving and starting success

Storage tips
Knowing that we need low temperatures and low relative humidity to extend seed life gives us some clues on how to store seeds to get the longest shelf life. This is key info if we’re trying to start seeds in spring that have been stored, or if we need to store extra or saved seeds. For the needed temperature levels, your standard home refrigerator is acceptable. Storage temps for cold foods are around the 40°F mark. However, humidity in a refrigerator is very variable. Humidity can skyrocket when doors are open, as condensation settles from warm room air settling on surfaces accumulates. Auto defrost cycles can also alter humidity. You’ll want to think about a desiccant like those silica packs to ensure that your seeds don’t get too moist. Store them in a plastic bag with the desiccant, and for added protection I always put mine in a sturdy container like a plastic box (or even a canning jar). Storing seeds in a freezer may help with the humidity issue, as any moisture that enters is frozen. You might also want to think about letting your bag or container warm up to room temperature before opening so that you don’t get condensation on the packets or the seeds themselves.

Sources:

Vegetable Garden Seed Storage and Germination Requirements – Nebraska Extension

Principles and Practices of Seed Storage – USDA

Seed Storage Guide – Johnny’s Select Seeds

Smith, R. D. (1992) Seed storage, temperature, and relative humidity. Seed Science Research 2, 113-116

120 Year Old Experiment Sprouts New Gardening Knowledge – MSU

Fail to Plan or Plan to Fail? Planning for a year of garden success

It seems like we’re always adhering to one schedule or another these days.  We have devices and planners to keep track of our appointments, our work schedules, kids schedules, and more. Heck, even the antique seed company clock in my office is telling me to order seeds.  It can seem overwhelming, so you might laugh if I tell you that coming up with a schedule, or a plan, for your garden can be beneficial.  It is especially helpful for vegetable gardeners or those who like to any kinds of seeds. 

Developing a yearly plan for the garden can help you keep ahead of the big tasks, help you stay on top of issues like weather, as well as make sure you get seeds started on time and transplanting done when it makes the most sense.  While some of this may be a review for seasoned gardeners, the number of questions and calls we receive at Extension (and the number of oopsies we see) means that the information could be helpful for many. 

Since my background is in vegetable production, I’ll focus there with some bits and pieces added for ornamentals when they fit. 

Do you have garden goals?

Whenever you are planning your annual vegetable garden, or planning on adding any ornamentals to your gardens or landscape, you should ask yourself a few simple questions.  When you’re dreaming of your garden during the winter is a good time to think of these goals.

1. What are my goals for the garden?  Do I have long-term goals?  What short-term goals can you set for this year to build momentum toward your long-term goals?

2. What resources am I willing to invest in the plants I’m ordering (money, time, water, space)?

3. What are the things I most want to grow?

4. What has worked (and what hasn’t) in your garden in the past?

While it may sound funny to say that you are going to set goals for your garden, it really isn’t all that far-fetched.

If you are planning to add ornamental plants to your landscape, you should think about what you want from those plants — are you looking for color or for structure? how about perennials vs. annuals (or biennials)?

When you are planning a vegetable garden, you should ask yourself not only what you want to grow, but how much. Are you just planting for fresh-from-the-garden eating, or do you want to preserve some through canning, freezing or drying? Are you growing just enough potatoes to eat for a month or two after the garden season, or do you need to select a variety that keeps well so you can store it?

Tips for Planning a Successful Garden

After you set your goals and decide what you want to plant, developing a schedule of when to do what is a good idea to stay on top of everything.  I can’t tell you how many years I had been planning on planting this or that, but then forget to buy what I need or start seeds on time.  A plan can help with that, as well as helping you space activities out over time rather than trying to get everything done in a hectic sprint.  This is especially helpful to new gardeners or busy folks who may forget to start or plant certain things at the right time (I wouldn’t be speaking from experience here.  Nope, this gardener has never been guilty of that.  I meant not to plant all of that garlic that I bought last fall.) To borrow the method used in a popular self-help book, you’re “scheduling the big rocks” as one of the habits of highly effective gardeners.

Keep in mind that it can be hard to “garden on a schedule” as weather always plays a factor in what we can and can’t do in the garden.  Given the wide variability in weather over the last few years in many parts of the country, which many scientists attribute to changing weather patterns due to climate change, it can be even more difficult to pin garden tasks to specific dates.  A plan can help you keep track of everything you need to do, but it should be flexible to take weather into account.

Starting Seeds Indoors

Germinating a variety of plants for our 2018 All-America Selections trials

If you’re starting seeds indoors, decide when you’re going to transplant them to the garden.  You can usually find this information on a seed packet, but you can find resources or consult your local cooperative extension office for guidance.  Keep in mind that warm-season plants typically need to be planted after your average last frost date (unless you’re adventurous and don’t mind gambling with a potential loss).  Cool season crops such as Cole crops (broccoli, cauliflower, cabbage, kale, etc.), leafy greens, and bok choi can be planted before the last frost date, but usually after the risk of a hard freeze has diminished.  For a map of the average date for last spring freeze/frost, check out https://www.ncdc.noaa.gov/news/when-expect-your-last-spring-freeze.  Note that these ranges are determined by analyzing the last frost dates over a 30 year period and the actual dates can vary due to weather variations (made even less predictable by climate change).

Choose the timeframe you wish to plant in the garden and count backward to when you need to start plants indoors. Put both the planting dates and the seed starting times on your calendar.   Also keep in mind that this is the earliest that you can plant warm season crops, but you can plant them later if it works better for you.  While we don’t typically share commercial links on this site, the best resource I’ve found for planning your seed starting and transplant dates for both vegetable and common annuals is https://www.johnnyseeds.com/growers-library/seed-planting-schedule-calculator.html

Direct Sowing into the Garden

For some crops like root crops, beans, leafy greens, and even some squash and cucumbers, direct sowing sees into the garden is ideal.  You can add timeframes to your plan based on previous practice, like knowing that you’ll sow carrots toward the end of March or early April, but keeping an eye on the weather can be even more helpful here.  Success here is more about temperature than timing.  Most plants have optimal germination temperatures, so you want to sow outside when the soil temperature (not air temperature) is at or near those levels.  The following resource has germination temperatures for common crops: http://sacmg.ucanr.edu/files/164220.pdf

If you’re lucky, you can search for local web-connected weather stations that have soil temperature probes.  For example, we have one at our office that we share with clients to make gardening decisions (http://mgextensionwx.com/).  If you can’t find one, NOAA has a few in each state for official climate data.  https://www.ncdc.noaa.gov/crn/current-observations.  Putting “check soil temperature” should be on your garden to-do list regularly until the temps get into good gardening range.

Spreading the planting and harvest through the season

If you’re aiming for harvests throughout the growing season, practice relay planting where crops mature in shifts throughout the garden season rather than all at once. If you’re planning on preserving some of your harvest for winter, planning on larger harvests at certain times in the season can get you the amount of produce you need for a big batch at the time that you need it. Some plants are good at producing through the season, but others, like determinate tomatoes and many beans have a one-time flush of production.  Of course, we also have the crops that are once and done, like carrots and radishes, that only have one harvest.  If we space out planting over weeks rather than planting all at once, harvests (or flowers if you’re growing annuals) can be spread out over a longer period of the season rather than everything maturing at once.  There’s generally a several week (to several month) window for planting crops.

For example, tomatoes can be planted as early as the average last frost date, but can be planted for several weeks afterward.  To figure out how late you can plant a crop, look for the first frost date and count backwards using the “days to maturity” information for the crop.  You’ll want to add on a few weeks to a month to account for having a harvest window and slowing growth as temperatures drop.  Keep in mind that many of the cool season crops can last well into the fall and winter, withstanding frosts and even light freezes, so replanting them for a fall harvest is ideal.

Planning out when to plant annuals, perennials, trees, and shrubs can also help make sure you get those plantings off on the right foot and can allow you to prepare in advance.  For example, if I want to add a tree to the landscape, taking the time to research trees and planting techniques, scheduling any prep of the planting area, sourcing the tree, and planting at the right time could all go on your calendar – that way you are prepared and ready to plant at the correct time.

Other garden tasks

While much of the work of a garden plan is front-loaded to the spring, there’s lots of tasks that we should be planning on doing regularly.  Scouting for and controlling insects and diseases, removing spent plants, mulching, compost turning, and more all come to mind.  Putting these on your schedule rather than  doing them when you think of them can really improve your likelihood of getting them done.  Also think about some of those big things you might have identified in the goals you set for the year.  Do you want to build a compost bin or develop new garden beds?  Plant some trees?  Take a soil test?  Putting these on your calendar can not only help you remember them, but plan ahead as well.  What do you need to do before you build that compost bin?  Do you need to buy supplies and tools (and look for bargains if you’re planning ahead)?  By planning when you’re going to accomplish these tasks, you can plan for success throughout the gardening year, improve your successes, and feel a little less hectic when the planting and growing goes full swing. 

A Cactus by Any Other Name: A Case of Mistaken Holiday Cactus Identity

Believe it or not, a cactus, of all things, is one of those plants that have come to represent the holidays and feature in the regular rotation of holiday houseplants. Then again, maybe it isn’t so strange amongst its peers that feature a flashy bulb-grown plant named for a horse’s head (the Latin name of amaryllis is Hippeastrum, literally meaning horse flower), a plant that has ugly flowers but brightly colored leaf bracts and leaks sticky and irritating latex when damaged, or some daffodil-like flowers that have musky odor so strong it makes some people nauseous.  But…..I digress. 

Back to the cactus.  However you see it though, the cacti that make their debut at the holidays are suffering under a case of mistaken identity.  What you typically buy as a Christmas cactus is not a Christmas cactus at all. It is actually a Thanksgiving cactus.  Now this wouldn’t be such a big deal, except that there is such a thing as a “Christmas cactus” — but you won’t find one on store shelves. Nay, it is hard to even find one in garden catalogs.  And this is sad, because the Christmas cactus is, I think, even more beautiful than the Thanksgiving cactus. 

How did we end up ignoring the beautiful Christmas cactus in favor of its holiday cousin?  It all comes down to timing and how we buy things for the holidays.  It seems that, as the shopping and holiday seasons creep ever upward on the calendar, retailers have little love for a cactus that is actually programmed to bloom at Christmas. They need something that blooms earlier so that it can be on the store shelves as early as possible. (At this pace, breeders will need to develop and Independence Day cactus for the Christmas shopping season.)

Therefore, the Thanksgiving cactus has been rebranded as a impostor stand-in for the true Christmas cactus. We won’t even talk about the Easter cactus, which just totally feels left out of the family (and yes, there is such a thing and it is beautiful).

These cacti were in cultivation in Europe by 1818 and various different species were being hybridized, probably most notably by W. Buckley.  The most notable hybrid, bred now named Schlumbergera ‘Buckleyi’ is considered to be the first actual “Christmas cactus” and associated S. x buckleyi hybrids are still grown as Christmas cacti.  Cultivars and crosses of S. truncata are the Thanksgiving cacti that have been rebranded as Christmas cacti.  They can be identified by their flattened stems (or cladodes or cladophylls) that have spiky, toothed edges and zygomorphic (now that’s a fancy word — it means that they have a two-sided, or bilateral, symmetry) flowers.  Most of the Thanksgiving cacti that have these characteristics.

W. Fitch (drew), Swan (engraved) – Bot. Mag. 66. 3717, as Epiphyllum russellianum Source: Wikimedia commons

You’ll most commonly find them in pink colors, but you can now find them in yellowish colors. The flower shape often leads to its nickname: “Zygo cactus.”

S. x buckleyi are the true Christmas cacti and form what is called the Buckleyi group.  Most of these have characteristics that come from the species S. russelliana, which was used in the early Buckley crosses. They can be identified by their rounded, less pointy cladodes and round, radially symmetrical flowers. They do have a similar growing form, but those in the know can tell the difference.

And for those following along at home, the Easter (or spring) cactus used to be considered part of the Schlumbergera genus (S. gaertneri) and then the Rhipsalidopsis genus, but now is classified as Hatiora gaertneri has radially symmetrical flowers but the cladodes are three dimensional rather than flat, elongated, and scalloped.  They have a wide range of colors, such as red, pink, and even orange.

Source: https://www.extension.iastate.edu/linn/news/it-thanksgiving-christmas-or-easter-cactus

Holiday cactus care

It’s a cactus, so it should be easy to care for – I just water it sparingly and keep it dry, right?  WRONG!

Whether you have a Thanksgiving or Christmas cactus (or an Easter one, for that matter), you take care of them the same way. Keys to their care come from their native habitat, which is not a desert but the cloud forests of costal south-east Brazil.  The high-altitude costal areas where they’re from are cool, shaded, and relatively humid with the mists and moisture rich air. They are epiphytic or lithophytic – meaning that they grow on trees and in crevices with decaying plant material rather than in the soil.  And while you don’t need to know this to grow them, the morphology of the flowers have developed to support the feeding of hummingbirds which act as their main pollinator.

  • Schlumbergera x buckleyi
    Christmas cactus
  • Schlumbergera truncata
    Thanksgiving cactus
  • Hatiora gaetneri
    Easter cactus
My holiday cactus collection

Since we don’t grow them epiphytically, when we pot them we need to make sure that we provide a light substrate for them to grow and to get plenty of oxygen to the roots. Potting mixes should have a high ratio of peat or coir and even some bark or other coarse woody material.  As for watering, you’ll want to keep the soil fairly moist, rather than dry.  You’ll also want to let them dry slightly between watering, but don’t think that they like to live the life of dehydration — you do need to keep them watered.

One of the reasons that they bloom at very specific time of year has to do with light and, to a lesser extent, temperature.  They are short-day (or rather  long-night) plants, so they flower as days grow shorter (or longer, in the case of the Easter cactus) and nights grow longer.  The Thanksgiving cactus will bloom with just a little shorter dark period than the Christmas cactus, which is why it blooms in late fall as opposed to the Christmas cactus that blooms closer to when days are the shortest around the solstice.  They will also bloom better and longer if they have cooler temperatures, so keeping them in a cool area of the house is ideal.  In high light situations the cladodes will turn red.  Keeping them too dark, however, will limit growth and keep them from thriving.

Since they are short-day plants, the plants need a period of several weeks where the period of darkness at night is 12 hours or longer for their flowers to begin forming.  This occurs naturally about mid-October, but you can delay flowering by using grow lights to lengthen the day (or keep in mind that bright indoor lights can also limit or reduce blooming).  Also, don’t be alarmed if they bloom at odd times through the year.  Since daylight coming into your windows can be altered by window treatments or films, the light levels can technically be “just right” for flowering at multiple times per year.  In my old office the tint on the windows created the right conditions at least once or twice per year – one year I had a Halloween cactus and the next it was a Memorial Day cactus. 

If your cactus does not flower, you need to move it to a spot where it gets at least 12 hours of relative darkness to initiate blooms (keep away from indoor light sources or windows near outdoor lights). Hopefully, you’ll have lots of colorful blooms for Christmas…..or whichever holiday your cactus celebrates. 

Sources

Is it a Thanksgiving, Christmas, or Easter Cactus? https://www.extension.iastate.edu/linn/news/it-thanksgiving-christmas-or-easter-cactus

McMillan, A. J. S.; Horobin, J. F. (1995), Christmas Cacti: The Genus Schlumbergera and Its Hybrids (p/b ed.), Sherbourne, Dorset, UK: David Hunt

Hydroponics, Aquaponics, & Aeroponics, Part Deux

Last month I shared some basic info on the major techniques for growing plants without soil, namely hydroponics, aquaponics, and aeroponics.  With such interest in these topics, I thought it would be good to dive a little further into the technologies used.  I’ll provide a bit of basic information about each type of system used for production and provide some resources for further technical reading if you’re interested in learning more. For some simple diagrams of the systems, check out this link (we don’t know if we can “borrow” the images, so we didn’t copy them over).

DEEP WATER

“Deep” water may be a bit of a misnomer, as it usually brings to mind thoughts of mysterious sea creatures living in the dark depths of the ocean.  Technically, the “deep” water can be just a few inches, as it is deep in reference to other methods.  This is perhaps the simplest and least expensive of the systems and can be a great entry point for beginners.

For deep water culture, the nutrient solution is held in a large container with some sort of floating support holding the plants.  The container is at least a few inches deep and holds a relatively high volume of water.  There are some containers that are designed for deep water hydroponics, but repurposed containers will work as long as they are food safe (meaning that they do not leach or break down).  Large plastic totes or even plastic buckets can be used.  As for supporting structures for plants, Styrofoam is the most common.  There are cell trays made of Styrofoam that are commonly used in production of small crops (or for growing transplants, which is a common use of this technique).  Foam boards with holes to hold pots can also be used.  Back when I was in grad school we developed hydroponic systems in my plant propagation class using foam insulation boards floating in large plastic totes.

One thing that you have to keep in mind for deep water culture is the need to incorporate oxygen into the system.  We often talk about the issue of overwatering houseplants and how it can damage roots  due to hypoxic, or low oxygen, situations.  Imagine how roots growing only in water would create situations for poor root and plant growth.  In all the other systems water flow helps incorporate oxygen into the water.  In deep water, there is no moving water and therefore no air incorporation.  The most common tool used for this, especially for small systems, is an aquarium air pump and air stones that help create bubbles in the system.

One benefit of this system is that it has a low level of risk when it comes to system failure.  There are few moving parts to break down and loss of electric doesn’t result in roots drying out due to loss of water flow.

EBB & FLOW

Ebb and Flow troughs in an aquaponics system. Note the floating styrofoam rafts. (I did research in this system during my master’s program.)

These systems, also called flood and drain systems, are one step of complexity above the deep water systems by introducing water flow.  Plants can either float as in deep water culture or be held in media that fills the container.  While many containers can be used, the most common are longer channels that promote water flow from one end to the other.  This system also introduces a reservoir of some sort that holds excess nutrient solution and a pump to deliver it to the container.  The level of water in the container is controlled by a raised drain pipe where solution exits the system back to the reservoir.

The DIY system I build using gutter with the Rwandan students (mentioned in the first installment on hydroponics) is ebb and flow.  The drain from the gutters is a few inches high within the channel, so the water raises those few inches before it drains out.  Some producers use long channels the width of those floating cell trays to grow plants in a relay fashion, planting them on one end and move them along as new rafts are added until they are harvested on the other end.

This system is common not only in hydroponics, but aquaponics as well.  Instead of a nutrient solution reservoir, the water from the tank(s) holding the aquatic stock (commonly fish, but could also be crustaceans like shrimp) is pumped into the plant channels and flows back into the system.  Systems may be based on continuous flow into and out of the system, but most commonly a timer is used to have multiple periods of flow and rest mainly as a means to reduce power usage.

NUTRIENT FILM TECHNIQUE (NFT)

This system evolved one more step above ebb and flow by limiting the volume of water used in the system.  Here, water is pumped from the solution reservoir to shallow channels where plants are held in pots or blocks of inert media such as rockwool.  Roots are not submerged in water, but instead grow within a thin film of solution that flows almost continuously through the system.  These channels have a slight slope where the end with the drain is a little bit lower than the end where the water enters.  The slope can be adjusted slightly to affect the speed of the water through the system.

This system is becoming common in production of leafy greens and herbs because it uses a much smaller volume of water.  But that small volume of water also presents a risk.  If there is a power failure or a clog in the tubing that delivers water to the system the roots can very quickly dry out and crops die, especially in situations of high heat and light.

DRIP SYSTEMS

Dutch bucket method for trellised crops

Perhaps one of the most commonly used systems across the world due to their simplicity, drip systems could be compared to a drip irrigation system used in the field.  Drip emitters are used to supply nutrient solution to plants in containers containing an inert media such as peat, coir, perlite, or grow stones. The containers can be pots, buckets, or bags/blocks of the media and are most commonly placed on the floor of the greenhouse or growing location with gutters to collect the solution that flows through the containers. A common method is using long, narrow bags filled with coir or other media referred to as the slab method.  Another common method, called the Dutch bucket method, uses buckets with drain holes in the bottom, commonly placed on a greenhouse floor.  Water trickles down through the media and roots and leaves the system through the bottom of the container.

Systems vary in the collection of the used solution.  Some may collect the solution that flows into the gutter and collect it in a reservoir to be reused, however some systems may allow the solution to flow out as waste.  These differences depend on the needs of the producer, available resources, and local regulations.

One of the comments that we got on my first article was about people growing container plants could technically consider it a form of hydroponics.  That might be a bit of a stretch, but you could technically consider growing container plants in soil-less media as drip or flow through hydroponics if you provide all of the nutrients through soluble fertilizers in the water.

WICK SYSTEMS

Typically used for small scale production, wick systems are one of the simple ways to grow plants without soil in terms of technology.  In this system, a passive wick uptakes nutrient solution from a reservoir and pulls it into the media (usually absorbent itself).  This wick could be a true wick, like a string made of absorbent material that inserts into an individual pot or it could be a mat made of absorbent material that pots or trays sit atop.

I’ve seen this commonly used perhaps not strictly in hydroponics, but for watering individual plants like African violets where yarn or twine is inserted into a drain hole in the pot and sits in water.  Technically this could be hydroponics if the media doesn’t contribute nutrients to the plant and they are all contained in the water instead.

KRATKY METHOD

This is probably the simplest of the methods and is used primarily by small scale producers and home growers.  It is similar to the deep water method in that there is no flowing water, but it is even simpler because there isn’t even an air bubbler.  In this method, plants are grown in large containers or buckets and the structure that supports them is fixed to the top of the container rather than floating.  As the growing solution is used up, the level of solution in the container decreases.  This creates a zone where the roots are exposed to air, providing the oxygen that the roots need.  The solution is kept at a level where at least the bottom portion of the roots are submerged in the nutrient solution.

AEROPONICS

Probably the most complex or technical system, aeroponics supplies water and nutrients to plants through a mist or aerosol emitted through pressurized nozzles.  The roots hang in a chamber without media and are misted every few minutes with nutrient solution.  The excess solution drops to the bottom of the chamber and is reused.  This system uses very small amounts of water, which can be beneficial for growing in dry areas but also creates a potential risk if the system or power fails.  Just like the NFT system, any prolonged period with out water will quickly result in plant damage or loss.  Beside power loss, this systems is also prone to clogged emitters, since the pressurized nozzles rely on very tiny openings to pressurized the solution.

Keep in mind that several systems that are sold for home or small scale production that are labeled as aeroponic, such as AeroGarden and Tower Gardens, don’t technically use aeroponics to grow since the solution isn’t applied as a mist or aerosol.  I would say they operate more like a vertical NFT system where water flows over the roots as it travels down the chamber.

RESOURCES

Hydroponic Greenhouse Production Resources – UMass Extension

Introduction to Hydroponics – Johnny’s Seed

All You Need to Know to Choose a Hydroponic System – Upstart Farmers

How to Start Growing with the Kratky Method – Upstart Farmers

DIY Hydroponics: Going soil-less at home and abroad

It seems that as interest in gardening grows, especially among younger generations, interest in different techniques that home gardeners use and different plants they grow are also on the increase.  You see the old standbys like straw bales and containers emerge.  Terraria, succulents, and air plants are having their moment.  And all kinds of technology driven indoor growing systems are all over the web, mostly hydroponic, but some aeroponic and aquaponic as well (we’ll talk about the difference in a bit – if you’re just here for that, skip the first 2/3 of the article).

I had been thinking about getting one of those new techno aeroponic growing systems as a demo for my office as a discussion starter for those interested in controlled environment growing whether on the homework commercial scale.  There is a general interest and need for basic education for hydroponics and aquaponics in the area that I hope to build extension programming around, so having something at the office could provide some interest from walk-in and social media clients.   I had dusted off a first generation AeroGarden that I found in the storage shelves in the office storage catacombs and set it up in my office.  It is a far cry from the new models I saw in those online ads that are outside of my budget for “toys to show off at the office.” It doesn’t have nice LED lights or connect to my phone via Bluetooth like the fancy new models.  Given its age, it produces more noise and heat than the lettuce and herbs I’ve tried to grow in it.  Maybe I’ll be able to get one of the fancy models one day.

Then I remembered a book that an urban ag friend of mine had written on building DIY hydroponic systems from common building materials and resolved to not only build a system, but incorporate it into my programming somehow.  The book, appropriately titled “DIY Hydroponic Gardens: How to Design and Build an Inexpensive System for Growing Plants in Water” by Tyler Baras shares plans for building a variety of types of hydroponic systems using basic building materials like gutters and lumber, drip irrigation tubing and fittings, and various other bits and bobs.  Tyler had been a featured speaker for the West Virginia Urban Agriculture Conference that I started and hosted when I worked for WVU Extension, so the book was on my radar – I placed an order.  (Note: I don’t get a kickback for sharing the book – just sharing a good resource that happens to be from a friend.)

Teaching Hydroponics to an Unlikely Audience

Image may contain: 3 people, including John Porter, people sitting, outdoor and nature
Learning traditional weaving methods using banana leaves. Banana leaf weaving is a common industry in rural Rwandan villages that allows women to provide modest incomes for their families.

As luck would have it, I had an opportunity to put the book, and my DIY hydroponic skills, to the test.  Our university does quite a bit of work with and in Rwanda and in May I had the opportunity to travel to Rwanda as part of a study abroad program with my Ph.D. advisor.    Rwanda is a very small country, just under the size of Massachussets, with a very big population by comparison – 12 million vs 7 million!  Feeding that many people is a struggle, and even though Rwanda produces a lot of produce (and more lucrative export crops like coffee and tea), it still imports a lot of its fruits and vegetables.  We were studying how innovation spreads in rural areas, and just before our trip I found a news article sharing that there would be an upcoming $8M USD ($8B RWF) investment in hydroponics in the country in order to increase production on the limited amount of land available.

In June I was scheduled to teach a group of Rwandan exchange students that are part of a sponsored program at the university, and remembering the planned investment in hydroponics I planned to add DIY hydroponics to the curriculum.  This is fitting, since most small-scale operations would rely on finding what materials would be locally available.  While the operations started by the investment would likely bring in “real” hydroponic systems, if small scale producers want to use the technology or if individuals want to build skills, they’re going to have to use what is at hand.

UNL CUSP Scholars students from Rwanda build a DIY Hydroponic System

Planting leafy greens and strawberries in the hydroponic system.

 

 

 

 

 

 

 

 

It was interesting teaching an audience who were interested in learning about the new technology, but have little experience or general knowledge on the subject.  Even more interesting was the fact that many of the students had not used or even seen some of the basic power tools we used in building the system.  I’m no shop teacher, but in the end the students not only learned a little bit about hydroponics and hydroponic systems, but also some skills using tools that they can apply in other applications.

Proudly showing off the team’s vertical hydroponic system.

 

 

 

 

 

Hydroponics, Aeroponics, & Aquaponics – Oh My!

Earlier I mentioned that there are differences between hydroponics, aeroponics, and aquaponics.  In some ways, they use similar basic setups.  All are based on soil-less growing using an inert media to support plants, supplying nutrients and water directly to the plant roots, and providing light to the plants using either natural sunlight or supplemental lighting.  Differences come from the source of plant nutrients and from how they are delivered to the plant.  I thought I’d take a few minutes to talk about the basics of each of the techniques so you can understand the differences just in case you want to buy or build your own system.  If there’s interest, I hope to focus on hydroponics and controlled environment agriculture over my next few blog posts – tell me what you’re interested in learning.

Most people are familiar with the concept of hydroponics.  This technique relies on roots being submerged in a nutrient-rich solution where the nutrient content is engineered from a variety of mineral sources.  There are a variety of different systems (that will hopefully be the subject of an upcoming blog) where the root zone interacts directly with the solution.  In some cases, roots are submerged in a large volume of solution while in others a film or shallow stream of water flows through the root zone.  Systems where roots are submerged in the solution may simply be a large reservoir where the plants float on top where systems relying on flow may involve a pump.  Movement of water adds another plant need -oxygen, which is required for respiration by the roots.  In systems where there is no flow, air is often pumped in to provide oxygen.

Most flowing systems are recirculating, where the solution returns to a reservoir and is pumped back into a reservoir to be reused.  While it may seem counterintuitive, these recirculating water based growing systems have been touted as production methods that conserve water.  That’s why some of the leading hydroponic production and research comes from areas of the world where water is scarce. Less common are flow through systems where water and nutrients are not recaptured but discarded after initial use.

Aeroponic systems have much of the same basic setup but instead of the roots interfacing directly with water solution it is applied as a pressurized mist.  These systems generally use a much smaller volume of water, but there are some drawbacks.  Failure of the system, such as an electric outage or clogging of the nozzles that pressurize the mist (which is a common occurrence) can quickly result in plant failure since roots can dry out quickly.  Several systems that are sold commercially that market themselves as aeroponic, such as the AeroGarden or Tower Gardens, are more similar to a flowing hydroponic system than a pressurized mist aeroponic system.

The plant growing structures of aquaponics are similar to those of hydroponics, with the addition of larger reservoirs to accommodate the addition of aquatic livestock such as fish (or sometimes crustaceans).  The waste produced by the stock provide the nutrients needed by the plants rather than an engineered nutrient solution.  These systems require having the technical knowledge to meet the needs of the aquatic stock and balancing those with the needs of the plants.  The addition of the aquatic stock also introduces a microbiome of bacteria and fungi, many of which are required for animal health but can also introduce pathogens that can negatively affect human health.

Are you interested in learning more about these systems?  What do you want learn about in hydroponic or other systems? Let me know in the comments and I’ll try to base some future articles on what our readers are interested in.