Vegetables – The Garden Professors™

Don’t be a garden gambler: You’ve got to know when to sow ’em, know when to plant ’em

For many gardeners around the US (and the northern hemisphere) the weather is warming up for spring planting season and many are itching to get out in the garden. But when is the right time to plant those veggies and flowers and not gamble on their success? Just like Kenny Roger’s character in The Gambler, knowing when to do something is important (this is where I’ll end the cheesy comparison – you’ve just got to come up with a catchy title sometimes).

I’ve spoken previously on this blog about understanding frost dates, which is important for planting warm-season crops like tomatoes, peppers, and cucumbers that won’t survive a frost. (You can read that article here.) But another temperature factor we must consider, especially for cool season plants that we plant BEFORE last frost is the soil temperature.

Soil temperature is especially important for direct sowing seeds in the garden, but it can also affect the success of transplants planted in the garden. For transplants, having an appropriate soil temperature supports root growth and development and helps plants get established faster.

Many warm season plants, especially plants like peppers, won’t establish easily or thrive unless soil temperatures are sufficient for root growth.

Why soil temperature matters for seeds

For direct sowing of seeds, soil temperature has a major effect on the speed of germination, which also affect the success rate of germination. Each different seed has a different optimum temperature for germination. If the soil temperature is below, or above, that level then germination can be slowed down. Slow germination can decrease germination rates through a few different avenues:

Germinating seeds are vulnerable to infection or decomposition by fungi and bacteria in this soil. When starting seeds indoors, this can be limited by using a sterile seed starting mix. But when direct sowing outdoors, there are any number of fungi and bacteria in the soil that will decompose a struggling seed/seedling. Some seeds sold for large-scale production will have a coating of fungicide on them that will provide a few weeks worth of protection. You won’t likely find this on home garden seeds, but it might appear if you buy seeds from a farm supply store or a catalogue that caters to farm-scale producers.
Seeds have a finite amount of stored energy. Once germination begins, the respiration rate of the embryo in the seed radically increases. If germination is slow, the embryo can expend the stored energy before the seed leaves emerge and start producing energy to support the developing seedling. (This also occurs if you plant the seed too deeply).

Below is a graphic I made for Nebraska featuring the best soil temperature range for major vegetable crops (notice how it also lines up with last frost dates). Just ignore the info on frost dates for Nebraska, unless you live in Nebraska.

Most of the resources you’ll find on soil temperature and germination are for vegetable crops. If you are trying to start seeds of ornamentals, you’ll likely have to find the information yourself. The seed packet will give you some indications of when to sow (before/after frost, or maybe in the fall for overwintering to break dormancy) and you can search online for guidance for specific plants. For info on starting seeds indoors, check out this previous article I wrote on the subject.

How to measure soil temperature

Of course, the tried-and-true old fashioned way is to use a thermometer. You can find a soil thermometer at many garden centers and retailers. You’ll want a soil thermometer because the ones for your kitchen likely don’t have the right temperature range – we’re measuring well below the temperature of a roasted chicken here. Instert the thermometer two to three inches into the soil and wait several minutes for the temperature arm to adjust before reading. Also keep in mind that temperatures fluctuate with the weather and throughout the day depending on temperature and the amount of direct sunlight hitting the soil surface – so you want to measure a few times to make sure the temperature is staying within the right range.

Now, the new technological way is to find a soil temperature monitoring station online. Soil temperature monitoring is a common feature of many weather stations these days and data is more available than ever. Many university extension services or ag research centers compile soil temperature maps for use by farmers and this data is also often accessible through NOAAA or weather.gov. In Nebraska, we have an extension program called CropWatch that provides average daily and weekly soil temperatures year round. We also have a weather station with soil temperature probes at our extension office (perks of having a meteorologist as a master gardener volunteer) and we (and our master gardeners) use it when providing information to clients. It can be hard to find a resource that provides soil temperatures nation-wide to share in the patchwork of private and public stations (and the National Weather Service site can be notoriously hard to navigate). There are a few online resources from the ag industry that provide a country-wide system, like this one.

And now its time for me to walk away, time for me to run

Unlike The Gambler you don’t want to wait until after the plantings done to count your money, er, check the temperature. Remember that knowing the soil temperature, whichever method you use, will help your plants succeed in the garden. If you do, your garden could pay out bountiful winnings all through the season.

By knowing the soil temperature, your seeds will turn into a sure bet. Source: Wikimedia Commons

Fair Judgement: garden lessons from a fair (and crop trial) judge

I love a fair! Which is a good thing since I find myself at a lot of them as an extension professional. It seems like fairs attract extension folks like honey attracts flies. We’re always involved in the 4-H activities – the livestock, project displays, and contests. Sometimes we pop up other places as well. The one thing that I get asked to do multiple times each summer is act as a judge for horticultural entries. Usually for 4-H youth entries, but sometimes for the open class where anyone can enter their best (or sometimes not so best) produce, flowers, and more. I thought I’d take a few moments to talk about what I look for as a judge, so if you ever want to enter your best tomatoes or dahlias at the fair you’ll know what to do to get the best ribbon possible. And even if you aren’t going to enter something into the fair, the rules and guidelines we use can help you select quality seeds and plants for your own garden or help you pick out the best produce at the grocery store or farmers market.

Produce items and flowers with their ribbons after judging. Each item is judged on its own merits and is not compared to the other entries (except for selection of a “grand champion” or for submission to the state fair).

The fact is, many of the same qualities I look for and skills I use when judging produce and flowers at the county fair are also ones I use as a trial judge for the All-America Selections (AAS) program. I recently attended the AAS/National Garden Bureau/Home Garden Seed Association summer summit and was discussing fair judging with some folks from seed companies. They were excited by the process, and especially by the fact that one of the things that I judge (and have gotten fairly strict about) is that the fair entry information contain the cultivar or variety name. They found this exciting because companies, especially smaller companies, put a lot of work into developing new cultivars, and when the general public identifies specific cultivars as being high quality (as in, I grow XXXX cucumbers because I think they are the best) or at least being able to identify the qualities of specific cultivars then it is sort of like a recognition of the plant breeders and distribution company’s work (and also puts money in their pockets). As home gardeners, it is important to know which cultivars or varieties work best for you and to be able to identify the qualities you prefer. It can also be handy to see cultivars out in “the wild” and be able to recall the name of plants you like, which is why the All-America Selections program has display gardens where you can see the edible and ornamental winning plants up close and personal. I’ve written about the trial process for this blog before.

Our display garden on the UNL Campus, which is our home garden for our TV show Backyard Farmer. We feature the garden each week on the show, which is one of the longest running locally produced shows in the US celebrating its 70th anniversary this year. Watch episodes.

Now back to the fairs – this year I used my judgmental eye at five county fairs in the course of three weeks – with three of those fairs in one week. I’m not sure why I’m so popular, maybe because I’m good at it or maybe because nobody else will do it. In either case, I do my best to not only judge fairly and by the rules, but also provide valuable feedback as a learning opportunity for youth. The whole point of fair entries and projects, from our point of view at extension, is not that a kid gets a blue ribbon (in Nebraska the top standard ribbon is purple, though, which I had to adjust to) but that we help raise blue ribbon kids. In some counties I actually talk to kids, interviewing them on how they grew stuff and giving them feedback on their entries. When I don’t interview, I fill out a score sheet and provide comments on positives and negatives of each entry.

Here are a few of the things that I look for when judging, and how they might help home gardeners:

Overall quality, appearance, and health – this is the one that most can identify with. Does the produce item or flower look appealing and high quality. Is it free of blemishes, diseases, bug holes, etc. You’d be amazed at the quality of some things we get at the fair. Of course, since I usually judge items for kids I do try to provide feedback on how to improve quality overall. Basically, my reference point is “would I buy this at full price a the market or grocery store”.
Correct preparation – this is one where lots of folks get tripped up. For produce items we are often looking for whether or not the item has been harvested correctly, whether or not the stem has been removed or trimmed properly. It varies by produce item. These rules seem superfluous and overkill, but they actually are based on guidelines for how to best prepare produce and flowers to extend their shelf life and storability. For example, in Nebraska our guide says to leave a ¼” piece of stem on cucumbers, to remove the blossom cap/stem (sepals) from tomatoes to reduce damage to fruit, to trim beet stems to 2”, to pull (not cut) rhubarb and leave 2” of the leaf blade attached, and so on and so forth. These guidelines all help reduce damage to produce items or keep them fresher longer – so these guidelines can be handy for home gardeners, too. Herb stems are to be cut a certain length and kept in water (like a bouquet) with the leaves below the water line removed. For flowers, rules will often state how large of a specimen to provide, and to remove the leaves below the water line. Rules vary by state and by fair, but many of them are fairly consistent here. You can find our Nebraska preparation guides for produce and flowers to see how best to harvest and prepare crops and flowers for storage or usage.
Uniformity of size, shape, color, etc. – this one also trips a lot of people up. First, most fair rule books will state a specific number of one item that needs to be provided, so that a judge may judge consistency and uniformity across multiple specimens. For example, our fairs require two specimens of larger produce items (slicing cucumber, zucchini, eggplant, etc), five specimens of medium size items (slicing tomatoes, carrots, potatoes, pickling cucumbers, beets, etc.), and twelve specimens of small items (cherry tomatoes, string beans, etc.). Flowers usually require five stems, but larger specimens like sunflowers may only require three. All the specimens provided in the exhibit should be as uniform as possible. All of the produce items and flower stems should be exactly the same size. Being the same level of maturity is also important and also leads to uniformity of color, especially in produce items. Color uniformity is especially important in flowers. I use this uniformity rule when judging our AAS trials as well – do the plants perform consistently across the whole plant in terms of harvest or flower appearance. This is a useful skill for home gardeners as well, as you can judge how well a specific cultivar or variety performs for you. You want to grow plants that perform well and provide consistent produce or flowers and not plants that only produce a few good items here and there with questionable produce or flowers mixed in.
Correct identification and cultivar names – as I stated earlier, the correct identification of the plant (like don’t enter a jalapeno pepper as a bell pepper) and the cultivar or variety are important. Knowing what the actual end product is supposed to look like is helpful for gardeners to know what they are growing, understand the traits that they want in the plants, and how to select the seeds or plants with the traits they desire. That’s why the seed company reps got excited about this part – because having gardeners identify specific (newer) cultivars as the ones with the traits they want is important. It takes garden selection from “I want a slicing tomato” to “I want this specific cultivar of tomato because I know it does X, Y, and Z, so I’ll buy it from this specific seed company that sells it. That in part is what we do with the All-America Selections trials. We try out new things (before they hit the market) to test them out for taste, color, disease resistance, and a whole bunch of other things to give a “stamp of approval.” So any time you see that AAS symbol you know there have been several judgmental eyes (including mine) have assessed those plants and found them worthy.

So next time you visit a fair take a look at the exhibits to see if you see what a judge looks for. And think about entering your produce or flowers in a fair near you just to see how your garden skills stack up with your neighbor’s. Even if you don’t win best of show you can have fun and learn a bit along the way. And even if you don’t enter at the fair, you can use your judgement to pick the best plants for your garden for years to come.

Sometimes you get to judge the “fun” stuff, too….like best dressed vegetable.

A Super Simple Salad in Stor(age): A DIY Home Hydroponics Example

Say the word “hydroponics” or the even more mysterious sounding “controlled environment agriculture” and the image that most people conjure in their minds is of large greenhouses or artificially lit rooms filled with complex hoses and tubes using all manner of technological gizmos to pump water and nutrients to plants. True, modern ag technology does allow for some pretty amazing and technical production of food but hydroponics can be super simple and so easy that just about any home gardener can do it.

Why grow hydroponically at home?

Growing vegetables can be pretty easy and straightforward for outdoor production – seeds, soil, water, and wait (sure, there’s a few other steps in there), so why complicate things by growing hydroponically? Aside from the challenge and the novelty that delights many gardeners, intensive growing with hydroponics can allow gardeners with the smallest of spaces to grow impressive amounts of produce in a short amount of time. Most of these systems also do well for winter production indoors with the use of grow lights or some good-sized south facing windows.

Hydroponic or similar-type production systems are the “craze” right now for folks wanting to grow some of their own produce at home, usually in smaller indoor spaces, but these systems can run into the hundreds or thousands of dollars making production less than economical. Plus, most of these systems require the use of pre-made plant/seed plugs that add to the expense.

Why is hydroponic production important?

On a larger scale, hydroponic and controlled environment agriculture has a few benefits that will help in feeding a growing population on a warming planet. Hydroponic production can be pretty intensive, meaning that it can grow a large amount of food in a relatively small amount of space. This makes it ideal for production in urban areas, which is important as most countries become more urbanized. It also cuts down on transportation needs to get food to consumers. This not only reduces fuel consumption but also, as we can see, makes it easier to get food to large populations when distribution becomes an issue. And as the term “controlled environment agriculture” implies crops can be grown using hydroponics in greenhouses or indoor farms no matter what the season or climate making it ideal for year-round production in areas where it is too cold or too hot part of the year to do so. This also means that hydroponics and controlled environment agriculture can be important mitigation strategies for climate change. When the temperatures or precipitation are no longer favorable for growing outdoor crops in certain areas, controlled environment ag can provide a stable source of produce with indoor production.

And as ironic as it sounds, growing hydroponically drastically reduces the amount of water used for production. Closed systems, which either recirculate water or grow in enclosed containers, use much less water than field production systems relying on irrigation.

A simple system example

Earlier this year I build some super simple enclosed hydroponic systems for demonstration at our Extension office and at the county fair. My goal was to show how easy hydroponic production can be – no need for pumps, tubes, or expensive equipment. The system was so simple that I built it with my non-horticultural interns as an onboarding/team building exercise.

The system we built utilizes the Kratky method of hydroponic production – a simple system where the plant is suspended on top of a container full of nutrient solution. In a typical recirculating hydroponic system where water is moved around air is introduced into the water that then provides oxygen to the roots to avoid hypoxic conditions that damage roots. Some static systems rely on introducing air (like using aquarium air stones) to introduce oxygen but the Kratky method is even simpler than that. Instead of introducing air into the solution, the level of the solution is reduced (usually through use and evaporation) as the roots grow keeping a section of roots exposed to open air. The setup is super simple and low maintenance – no moving parts, no electricity (unless I need to use lights for indoors). Just plants, a medium to hold them, a container and a nutrient solution.

How To Start Growing With The Kratky Method - Upstart University — The Kratky Method, Source

I’ve seen the systems made with all kinds of containers but we chose 25 gallon storage totes because they are inexpensive and pretty easy to come by. Having a lid that is relatively easy to cut/drill also makes these kinds of containers ideal to make multi-plant “beds” but I’ve also seen lidded buckets used as a single-plant system.

To hold the plants we used plastic net pots that you can find at garden centers that sell pond or aquarium plants (or order) that are also now common at hydroponic supply stores, if you’re lucky enough to have one in town. You can also use plastic orchid pots or standard nursery pots, perhaps adding extra holes for roots to grow out. We used 6 inch and 2 inch pots to plant a variety of sizes.

Net pots in the system, with holes made slightly smaller for them to fit and not fall in.

Next we cut holes in the lid slightly smaller than the diameter of the pots so that they sit on top and don’t fall through. You can do this by tracing and cutting with a sharp object, or use a drywall hole saw that you use with a drill to cut a perfectly round hole. We used one with adjustable sizes, rather than buying individual sizes.

And now, to plant!

The pots were then filled with an inert, soil-less medium to support the plants. We used a puffed clay stone called LECA, but you can use rockwool or hemp fiber blocks made for hydroponic starts, large particle perlite, or even something like a poly fiber filling (like used in sewing) – just something that won’t break down to hold the plants in place.

Some of the plants I had started in fiber cubes so those easily went into the LECA, but we did end up buying a few transplants. Since these were started in some sort of potting soil we had to wash as much of the soil off as we could. We placed larger plants like peppers and kale in the large pots and smaller plants like herbs in the small pots.

As for plant selection, leafy greens and herbs like basil and parsley are easiest and can use smaller containers and pots. Plants like tomatoes and peppers will need bigger containers and pots and will also require more light and heat if you are growing them indoors.

A solution for easy nutrient solutions

And last but not least – the nutrient solution. Since we are growing without soil we have to provide basically all macro and micro nutrients. We are used to supplying nutrients like nitrogen and phosphorous, but not so used to supplying things like manganese and molybdenum. This one is probably the scariest to those new to hydroponics, but there are some easy options out there for small scale production that are “off the shelf” solutions. Rather than worry about mixing up nutrients by hand, these pre-made mixes make it easy for home growers to try hydroponics. They come in two or three part sets of either liquid or solid fertilizers, because some of the chemicals used will react and precipitate out into a sludge if kept together in concentrated form. Just mix according to package directions and you’re good to go. If you are growing anything like tomatoes or peppers that require flowering and fruiting, you’ll want to make sure the formula is for flowering plants. Regular water-soluble fertilizers might do in a pinch, but for long term growth you’ll want to invest in something with all micronutrients.

Storage tote hydroponic system, sitting in the office courtyard.

If you’re planning on refining your technique, you might want to invest in a pH meter or TDS (total dissolved solids) meter to fine tune the solution based on the minerals dissolved in your water. And if you have really hard water you can usually get an additional nutrient product to account for the pH and calcium levels to balance things out.

So now we just filled the totes with the solution all the way up until the bottom few inches of the pots were covered. We kept watch on the solution and added water as needed, keeping in mind that as the roots grow out of the pot the nutrient solution level needed to be low enough to expose around 2/3 of the roots to air.

The nutrient solution is only a few inches deep in the bottom of the tote at this time, allowing roots to be exposed to air for oxygen uptake.

As the plants grow, you’ll just want to keep an eye for signs of nutrient deficiency and add nutrients to the water as needed. The solution should be completely dumped and replaced every 6-8 weeks, as the plants rapidly deplete some nutrients, allowing some to build up to toxic levels. You can typically just pour the solution out on the garden or lawn, as it only contains plant nutrients. However, you’ll want to make sure not to keep dumping in the same spot to avoid build up of salts in the area. Spraying the area with a bit of water from the hose can help wash it off of plants and start diluting it into the soil, rain and weather should do the rest of the job. But if you are in an area with little precipitation, you may also want to take care since there won’t be a lot of water to dilute the nutrient build up over time. And just remember, if you harvest and completely remove crops, pull apart and clean the system with some good soapy water and a sanitizer (bleach works well). You should do this every few months if you have a long-lived crop in the system.

In a nutshell…..

A simple system like this one can be a great way to explore a new growing technique, even for beginner gardeners. After these were set up, we basically left them in our courtyard all summer with little to no maintenance, except adding water earlier in the season and changing out the nutrient solution once. If you need a bit more info, or want to try something a little more complex, there are some great resources out there for small systems that I’ll share below.

Resources:

Growing Lettuce in Small Hydroponic Systems – Univ of FL Extension

How to grow with the Kratky Method – Upstart Farms

Small-scale hydroponics – Univ of Minn Extension

Home Hydroponics – Illinois Extension

Everything is chemicals: the myth and fear of “chemical-free” gardening

“Chemical-free” – a term I’ve seen several times attributed to many products, especially food and produce at farmers markets and even in gardening circles these days. This term is often misused to describe plants grown without the use of any pesticide, either conventional or organic. I have my thoughts that I’ll share later on that subject but first let’s talk about this “chemical-free” that gardeners, farmers, and others use and why its not only a myth, but a dangerous one at that.

Ain’t such a thing as “chemical-free” anything

At face value, the term “chemical-free” would literally mean that whatever the label is applied to contains no chemicals. That the entire item, whether it be animal, vegetable, or mineral is devoid of any and all chemicals. Factually this can never, ever be true. Everything that exists is made of chemicals. Oxygen, water, carbon dioxide, and any simple molecule, by definition, is a chemical. Plants and animals are organized structures filled with complex chemicals. Even you and I, as humans, are walking, talking bags of chemicals. The air we breathe, the food we eat, and the water we drink are all composed of a great mixture of chemicals. The use of the term “chemical-free” to describe anything is uninformed at best, and intellectually dishonest at worst. But a bigger problem, as we’ll discuss later, is that using the term can cause confusion and even fear of things as simple as food and as complex as science and medicine.

Expert reveals how even natural foods contain chemicals | Daily Mail Online — The “ingredient list” of a peach.
Source

What most people intend to say when they use the term “chemical-free” in relation to plants or produce is that they are produced without use of pesticides or conventional “chemical” fertilizers. Therefore, a better term to use would be “pesticide-free” instead of “chemical-free” as it more accurately represents the situation. Many may ask why the term “organic” or “organically grown” couldn’t also be used to describe “pesticide-free” plants. And while those terms would be accurate, organic production can involve the use of organic pesticides that are derived from natural sources such as plants, bacteria, or natural minerals. Natural sources of fertility for plants, such as composts and even soil itself, are all composed of a myriad of chemical substances. Plants don’t differentiate between the chemicals they uptake from compost or soil and those from fertilizers. To plants, nitrogen is nitrogen and phosphorous is phosphorous no matter where it comes from.

For some clarification on what different growing and production terms like these mean, check out this lecture I gave for the Oregon Farmers Market Association earlier this year.

While many have a strong opinion on the use of pesticides and fertilizers, I’ll state here that the use of any pesticide, organic or conventional, must follow the label on the container by law. And the use of any pesticide according to the label instructions means that the use of that pesticide should present a minimal risk to the health of the applicator, consumer, off-target species, and the environment. And don’t use any home remedy recipes or products that aren’t labeled (or at least scientifically researched) for use as a pesticide. In most cases these remedies aren’t effective, in some cases they can be more dangerous to human health or the environment than the pesticide they are trying to replace. And applying them as a pesticide could also be illegal.

Reading Pesticide Labels - Pests in the Urban Landscape - ANR Blogs — Pesticide label signal words that denote relative toxicity of a given pesticide.

Any gardener or producer, whether they use pesticides or not, should also be practicing Integrated Pest Management (IPM) to decrease or mitigate the effects of insect and disease pests on their plants. For those using pesticides, use of the least toxic pesticide that offers control of the problem should be the last step in a series of steps to avoid damage from pests after a threshold of damage has been reached. For those who don’t use pesticides, IPM should be a central practice in their gardening or farming practice. Unfortunately, the tradeoff for not using pesticides is often time and labor, so successful “pesticide-free” growing often involves more work (and for produce at the market or grocery store, a higher price). I have seen some gardeners and farmers who don’t use pesticides and don’t make an effort to practice IPM, taking whatever plants or produce mother nature and her children deal them. I’ve sometimes referred to this type of growing as “organic by neglect” as I see insect and disease riddled produce harvested and even sold at local farmers markets.

Why does it matter?

“So what if I use the term ‘chemical-free’? It doesn’t hurt anyone,” you may say. While this may seem the case, the use of the term “chemical-free” has risen as a result of what many call chemophobia, effects that reach far beyond the garden or the farmers market. This kind of thinking leads to the incorrect notion that all “natural” remedies are safe and all “synthetic” remedies are dangerous. True, many chemicals do pose a risk to human, plant, animal, and environmental health but many do not. Just like not all natural substances are safe. Poison ivy, anthrax, botulinum, and cyanide are all natural and cause everything from a skin rash to instant death (sometimes I get poison ivy so bad I wish for instant death).

This chemophobia can lead to, or is a symptom of, a broader mistrust of science, the scientific process, and modern medicine that has developed in society in the last few decades. Many attribute this to an anti-intellectual or anti-science stance in society resulting from mistrust or political saber-rattling against universities, education in general, science/scientists, “big Pharma”, “big Agriculture”, and others. As a result, the news is filled with people who eschew well-researched scientific advances that have been proven safe and instead turn to home remedies that have no such guarantee of either effectiveness or safety. The results can be worse than the effects of the proven advance the person was trying to avoid.

While the outcomes of “chemical free” gardening might not have such dire consequences as immediate death, the misuse of such terms can feed into a cycle of anti-science cause and effect, serving as both a cause and a symptom of mistrust of science and the scientific process. While everyone has a right to choose whether or not they use pesticides (or any other scientific advancement), making such decisions from a place of knowledge instead of fear is paramount for success and continued advancement.

Sources and further reading:

https://www.columbiasciencereview.com/blog/debunking-the-myth-of-100-chemical-free-slogans

https://www.sciencedirect.com/science/article/pii/S0278691520302787

https://www.canr.msu.edu/news/chemophobia-fearing-chemicals

https://www.businessinsider.com/what-chemicals-are-in-an-all-natural-banana-2017-6

Counting the Days to Maturity: Calculating planting dates for fall vegetables

While most of the US is still seeing sweltering hot temps, the cool temps of fall and winter aren’t really all that far away for those of us unlucky (or lucky) enough to not live in a tropical climate. The tomatoes, peppers, cucumbers, and other warm-season crops planted back at the beginning of summer are still puttering along, even if they might be getting a little long in the tooth and starting to look a little worse for wear ( especially if disease has ravaged them). For those who aren’t quite done with gardening for the year or who want to reap the bounty of fall crops and get the most out of their production space, fall gardening can be a great tool to extend the garden season. But knowing when to plant what is tricky, especially when we are talking about different weather patterns and frost dates all around the country. So a bit of weather data, info from the seed packet or label, a touch of math, and a calendar can be great tools to figure out when you can plant no matter where you are. Of course if you do live in one of those warmer tropical areas your planting calendar is kind of turned on its head from what us more northern gardeners face. You may prefer to time your planting to avoid high heat.

The first thing to think about is what you can plant. Cool-season crops such as the Cole crops (cabbage, kale, broccoli, etc.), leafy greens (lettuce, spinach, Bok choi, etc.), root crops (radishes, beets, turnips, scallions), and some cool weather loving herbs like cilantro and parsley are all par for the course for a garden going into cooler fall and winter temps. Depending on when you have extra space in your garden to plant and how long your growing season is you can often sneak in a late planting of fast-growing warm season crops to mature before the last frost. Beans, cucumbers, and summer squash all have varieties that are fast maturing and can be started mid-summer for an early fall harvest. Unfortunately, as of this writing the window for those warm-season crops has passed for me, but others in warmer zones may still have time.

One question I get asked often is whether you should start indoors or out. I always tell folks that for things normally direct-seeded, like beans or lettuce, sow as normal. For things that are normally started indoors, the choice is yours. Cole crops are started indoors in spring because they need warmer temps to germinate. Since it is hot outside, you won’t need to grow them indoors for the heat (though it may be too hot outdoors if temps are over 85). You can start them in containers in a protected area outdoors instead of trying indoors. Theoretically you could direct seed them into the garden, but management is difficult to keep them watered, weed-free, and alive out there in the cruel garden world.

To know what you can plant and when, the first bit of info you’ll need is from the seed packet or label (or do some research if you know the cultivar/variety). You’ll want to know the “days to maturity”, which is an estimate of how long it will take to go from seed (or transplant) to edible crop. For those warm season crops, you might want to shop around because those days to maturity can be wildly variable – you can find beans that mature in 60-65 days and some that take 100+. You’ll want to choose faster maturing varieties.

Assuming that you’ll want a harvest window longer than a day and given that plant growth slows down as temperature cools (respiration is temperature dependent so plant processes slow down as temperatures drop), you’ll want to add a few weeks to the maturity days to take that into account. This should be sufficient for cool season crops that will survive well past the first frost and freeze dates. The aim for cool season crops is to get them close to a mature size before cold weather sets in since their growth will slow down at that point. For warm season crops you’ll want to add a little more time to provide a cushion against frost which will kill the plants. For info on killing temperatures of certain crops, check out my previous article here.

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For example, if I wanted to plant Asian Delight Bok choi (I fell in love with it when I trialed it for the All-America Selections program) I’d see on the packet that it has an average maturity time of 37 days (which is pretty damn fast). My math would be:

37 days (to maturity) + 14 days (harvest period) + 14 days (fall factor) = 65 days

Next, you’ll need to know a bit of weather data – more specifically the expected date of your first frost/freeze. You can find this on the website of your local National Weather Service office, or get an idea from the map below. (This data is usually updated every decade or so – you’ll want to check it every few years for updates as the dates have been changing due to climate change.) The date ranges given are usually a median, meaning that half of the frost days fall before and half fall after the given dates. Keep that in mind – sometimes frost will come earlier or be much later.

I live in Omaha, Nebraska so our median frost date (according to the map) is Oct 10. Now I know that I need to plant my Asian Delight Bok choi 65 days before Oct 10. I can grab a calendar and count backward from October 10 (or I can cheat and use an online date calculator like this one) and see that the suggested planting date is August 6. Since I missed it by a week I can decide if I want to gamble a little and still plant since I know that it could very well frost later than Oct 10 and that the Bok choi will survive much later into the season anyway. But it gives me an idea of what to expect.

Had I wanted to plant something like beans for a late crop, my calculation would have definitely shown me that it was too late, letting me know that I shouldn’t waste my time. For example, Blue Lake beans take around 55-60 days to mature (almost twice as long as my Bok choi), plus I need to add that extra 14 days for the frost factor meaning that I would have had to plant 97 days before first frost, which would have been in early July for me.

You can extend the time you have for growing fall crops by using season extension techniques like row covers, low tunnels, cloches, etc. For row covers, the materials you buy such as the spun fabric row cover will offer a certain number of degrees of protection. For example, a medium weight row cover might offer 8 degrees of protection, meaning it will be 8 degrees warmer under the cover than the air temp. Keep those in mind when planning your fall garden. Perhaps we’ll have to talk about those in another article soon.

Sources:

Fall Gardening (Nebraska Extension)

Fall Vegetable Gardening (Virginia Cooperative Extension)

Fall Frost Info (Weather.gov)

Water: Garden Friend….and Foe? – Water, Relative Humidity, and Plant Diseases

We all know that water is essential for life and that we have to ensure our landscapes, gardens, and houseplants all have a sufficient supply of the stuff. Forget to water your garden during a hot, dry spell and it could mean disaster for your plants. But water can also create issues for plants, usually when it is in an overabundance – water helps spread and develop diseases on foliage and excess soil moisture can damage roots, creating opportunities for root rots and other diseases. How do you meet the water needs of the plant while also avoiding issues associated water? Understanding how water affects disease organisms will help, along with some tried and true Integrated Pest Management Strategies.

Water and Pathogenic Microbes

Both bacteria and fungi require water to grow and reproduce. Most do not have a mechanism to actively take up and manage water, so they uptake water mainly through osmosis. This means there must be some form of water present for those microbes that are actively growing and especially for processes like reproduction which use not only a lot of energy but might also be required to carry spores in order to spread.

File:Septoria lycopersici malagutii leaf spot on tomato leaf.jpg - Wikimedia Commons — *Septoria* leaf spot, a common fungal disease of tomato that requires water for initiation and development.

Both pathogenic microbes and beneficial (or neutral) microbes require water to thrive. It is one side of what we refer to as the disease triangle. Water (along with temperature) are major components of the “favorable environment” side of the triangle, with the other sides being a plant capable of being infected and a population of pathogens capable of infecting. Those last two sides meaning you have to have a population of the pathogen big enough to initiate or sustain an infection and a plant that can actually be infected by that pathogen. For example – one disease spore may or may not be enough to start an infection (depending on the pathogen), but several hundreds or thousands definitely can. And the pathogen has to be one that can actually infect the plant – it doesn’t matter if you have a million spores of Alternaria solani (one of two closely related fungi that cause early blight in tomatoes) on your cucumber plants, they likely won’t get a disease. But if there are spores of A. cucumerina, a different species, you’ll likely get leaf spot on those cucumbers. But it doesn’t matter if you have both a susceptible plant and a pathogen, there has to be a favorable environment (water and temperature) for there to be a disease infection.

As this paper points out, water in the form of liquid (rain, ground water, dew, etc) and vapor (air humidity, fog) can provide the environment for microbe development in the soil and on foliage. Microbes in the soil are ubiquitous as water is typically available in most soils (except in droughty or arid areas) , but excess soil moisture can create booms in populations for both the “good” microbes and the “bad” ones. Microbes that live on foliage (sometimes referred to as epiphytic since they rely on moisture from the atmosphere) are much more likely to be water stressed since they are exposed to the atmosphere. When there isn’t water available on the surface of leaves (from rain, fog, etc.) microbes tend to colonize around areas where water leaves the plant – stomata and to a lesser extent around tricomes and hairs.

The paper also points out high atmospheric humidity is positively correlated with the number of fungi on a leaf surface. It’s also a requirement for diseases microbe spores to germinate, for filamentous fungi to break dormancy, for pathogen survival, for microbe movement on the leaf surface, and for disease infections to be sustained. It is also shown that heavy precipitation increases water availability to these microbes thus hastening their growth. Precipitation also dislodges and disperses pathogen spores and cells to adjacent plant tissues, and to leaves of nearby plants. High humidity also makes leaf cuticles more permeable and promotes opening of the stomata, which can serve as an entry point for pathogenic infection.

Once inside the plant, microbes such as fungi and bacteria can thrive on the aqueous environment inside a plant, moving easily between cells or into the vascular tissue (depending on disease). Pathogens that thrive in wet conditions, however, may initiate water soaked lesions on the plant to develop conditions favorable to their growth.

Water, water everywhere – so is there anything you can do?

Of course, water is naturally occurring and in most places falls from the sky in some form or another. In some places very little precipitation falls, in others there’s a lot. And don’t forget about the humidity, dew, and fog (which are often more common in places that get more rain, but provide moisture even in dry climates). There are a few places where the atmospheric moisture levels are in that “just right” zone to support plant growth but not pathogen growth, which makes agricultural production of certain crops easier. You could consider these areas the “Goldilocks” zone for crop production. For example, a lot of seed crops are produced in the Midwest and arid north West, potatoes in Idaho, apples in Washington, etc. The conditions there mean that, at least when those crops were getting established (before the advent of modern pesticides) in those regions, disease pressure was low.

You can’t stop the rain, of course, if you’re in a place both blessed and cursed with abundant rainfall or atmospheric humidity. But there are some things that you can do reduce the likelihood of diseases spread or supported by that water and humidity.

Evidence shows that there is a positive correlation between the density of planting and disease incidence. Therefore, proper plant spacing and pruning can do at least three major things. First, having space between plants, especially in the vegetable garden, can reduce the splashing of pathogens from one plant to the next during a precipitation event. Second, it increases air flow through the plant, which can reduce the likelihood of pathogen spores that might float in and land on foliage. Third, it reduces humidity in the immediate microclimate around the plant. The increased air flow in addition to the reduced amount of foliage that is releasing water through transpiration can have a significant effect on the humidity, which can have a big effect on the germination, establishment, and survival.
Utilize diverse planting plans in the vegetable garden and the landscape. Research shows that while having a variety of plants increases the diversity of disease organisms, it actually reduces the infection rate possibly because pathogens splashing from plant to plant are less likely to find a host plant if they are surrounded by non-host plants. This practice is promoted in intensive vegetable plantings such as square foot gardening.
As stated earlier, precipitation can drastically increase the population of microbes on foliage. This also includes water from overhead irrigation. For example, this study found that overhead watering of cabbage led to significantly higher and faster rates of spread of the black rot fungus as compared to drip irrigation. Therefore, reducing or avoiding overhead watering can reduce the likelihood of disease incidence.
Timing of watering may also contribute to disease development. The dew point, which usually happens during the night time hours, is when the air is totally saturated at 100% relative humidity and therefore cannot hold any more water. This is the point where excess moisture is deposited as dew on surfaces (another source of water on the foliage) and little to no evaporation of water already on surfaces happens (learn more at weather.gov). As shared in this book chapter review, lower temperatures resulting in reaching the dew point can extend the time leaves are exposed to high moisture and result in higher disease incidence.
As our own GP Linda Chalker-Scott points out in this review, mulching not only retains soil moisture, reduces erosion and more but also reduces the incidence of disease in plants by reducing the splashing of soil or spores from rain or irrigation onto the plant. This drastically reduces disease spread from pathogens found in the soil or on plant debris. The organic matter from organic mulches also has the benefit of increasing the population of beneficial microbes, which out-compete the pathogenic microbes.

Mulching and drip irrigation can both significantly reduce disease incidence in gardens.

Crop rotation, where crops are not grown in the same soil or plot for a number of years, also reduces disease incidence by reducing pathogen loads in the soil or from crop residues left in the garden. This study shows significantly reduced disease incidence on potato and onion when a crop rotation plan of four years is utilized (meaning that either onions or potatoes are not planted in the plot for a minimum of four years, with other crops planted between those years).
If root rots and pathogens are a problem, try improving drainage around the garden. Adding organic matter can help with water permeability of the soil over time. Raised beds can also drain faster than in-ground gardens.
Of course, if you’re having lots of problems with certain diseases on your plants, these cultural controls may not be enough. Finding resistant varieties may be a necessary step in breaking the disease cycle in your garden.

Overview

While water is required for plant growth, it can cause issues with plant diseases if there is too much or if it lingers on the wrong parts of the plant for too long. Water from rainfall, irrigation, high humidity, fog, and dew can all lead to the initiation, development, and longevity of plant fungal or bacterial diseases. Reducing the amount, persistence of water or humidity on or around foliage can significantly reduce the likelihood of plant disease incidence. Methods such as reducing overhead irrigation, timing of irrigation, mulching, and crop rotation are key cultural methods in reducing diseases spread by water.

Sources:

Aung, K., Jiang, Y., & He, S. Y. (2018). The role of water in plant–microbe interactions. The Plant Journal, 93(4), 771-780.

Burdon, J., & Chilvers, G. A. (1982). Host density as a factor in plant disease ecology. Annual review of phytopathology, 20(1), 143-166.

Café-Filho, A. C., Lopes, C. A., & Rossato, M. (2019). Management of plant disease epidemics with irrigation practices. Irrigation in Agroecosystems, 123.

Chalker-Scott, L. (2007). Impact of mulches on landscape plants and the environment—a review. Journal of Environmental Horticulture, 25(4), 239-249.

Krauthausen, H. J., Laun, N., & Wohanka, W. (2011). Methods to reduce the spread of the black rot pathogen, Xanthomonas campestris pv. campestris, in brassica transplants. Journal of Plant Diseases and Protection, 118(1), 7-16.

Rottstock, T., Joshi, J., Kummer, V., & Fischer, M. (2014). Higher plant diversity promotes higher diversity of fungal pathogens, while it decreases pathogen infection per plant. Ecology, 95(7), 1907-1917.

Wright, P. J., Falloon, R. E., & Hedderley, D. (2017). A long-term vegetable crop rotation study to determine effects on soil microbial communities and soilborne diseases of potato and onion. New Zealand Journal of Crop and Horticultural Science, 45(1), 29-54.

SUPER Thriving Lettuce?

The Garden Professors have previously written about the ubiquitous garden center product, SUPERthrive, here and here. The manufacturer claims a plethora of beneficial uses for SUPERthrive —everything from Christmas tree care to turf to hydroponics. They claim SUPERthrive will “revive stressed plants and produce abundant yields” and that it “encourages the natural building blocks that plants make for themselves when under the best conditions” thus “fortifying growth from the inside out,” but I know of no body of rigorous, peer-reviewed literature to support any of those claims (1, 2, 3, 4). In fact, I’m not entirely sure what those claims really mean, but I’m encouraged on their website and bottle to use it on every plant, every time I water, to receive these amazing benefits!

A test case

The hydroponics claim intrigued me because during the winter months I grow plants hydroponically under lights. One of the benefits the manufacturer claims is “restores plant vigor” and “works with all hydroponics systems.” As a plant scientist, and knowing something about the ingredients, I was skeptical to say the least, but I thought that if SUPERthrive was going to show any beneficial effect it would surely be in hydroponics since that is a more uniform environment than outdoors. So, I shelled out my $11 for 2 oz (the things we do for science!) and set off to design a simple experiment.

The hypothesis

A typical experiment like this starts with what we call the null hypothesis (denoted “H0”). The null hypothesis is defined prior to the experiment and often states that we think there will be no difference between the treatment and control. In this case, my null hypothesis is that the SUPERthrive treatment will have no effect on the mean fresh weight of the harvested lettuce relative to the control lettuce. Note that I haven’t made any hypotheses about other parameters that might be important, e.g., flavor, compactness, number of leaves, color, disease incidence, survival rate, etc. For this experiment I am interested in only one thing: total harvested weight as a signifier of healthier plants.

After the data is collected and analyzed, we decide whether to accept or reject the H0 by running an appropriate statistical test. If there is no statistically significant difference, then we cannot reject the H0—that is, we accept the H0 that there is no difference between treatment and control. If there is a statistically significant difference between treatment and control, then we say we reject the H0 and conclude that the treatment did have an effect. Keep in mind, sometimes no difference between treatment and control is a good thing, e.g., in toxicity studies.

Experimental design

With my skeptical spectacles on, I set up my experiment to test my hypothesis. I made a six-gallon batch of hydroponics nutrients suitable for leafy greens. I split the batch in half and added SUPERthrive, per the manufacturer’s dilution recommendation, to one of the three-gallon aliquots as the treatment. I then divided the control and SUPERthrive treatment each into six individual, identical, two-quart containers. I thus had six independent replicates of a treatment and a control. (See Figure 1 below for a schematic of the experimental design.)

To further avoid any experimenter bias, I had my wife assign numbers randomly to each container, record which were SUPERthrive treatment and which were untreated control, and then re-sort all the containers. I had no idea which containers contained which nutrient mix. I did not open the “secret decoder envelope” until after all measurements were complete!

Figure 2. Identical 2 quart containers randomized on day 1 in the hydroponics solutions. This kind of hydroponics is called “Kratky” or passive. Enough nutrient solution is supplied at the beginning to last the plant for its entire life-cycle.

Into each of the 12 containers I placed a 12-day-old lettuce seedling, taking care to select plants that were of equal size and leaf number. The containers were then placed under my lights (cool white T8 fluorescent) for the remainder of the experiment. I rotated the rows of plants several times to try to control for any edge effects in my grow area. After 30 days in the containers, I harvested and weighed each plant.

*Figure 3. Plants after 30 days of growth.*

What did my experiment show?

The graph below is a box and whisker plot that shows the spread of the data and the mean for each group in grams of harvested fresh weight of the plants (roots were removed). In my experiment, the SUPERthrive treatment showed a clear drop in harvested fresh weight! In fact, the heaviest SUPERthrive plant weighed less than the smallest control plant, and the SUPERthrive set was much more variable in harvested weight. These results surprised me a bit.

*Figure 4. Box and whisker plot of lettuce plant fresh weight. Master Blend: Master Blend nutrients; Master Blend + ST: Master Blend nutrients plus SUPERthrive (0.9 ml/gal.)*

A standard statistical test (Student’s T-test, unpaired, two-tailed) was performed to show that that there was in fact a statistically significant difference (p<<0.01) between the two groups. Thus, we can reject the H0 (remember our null hypothesis is that there will be no treatment effect) and conclude that there is a difference between treatment and control harvested weights, with the treatment mean plant weight being significantly smaller than the control mean plant weight.

What can we make of this experiment?

Well, we need to keep in mind a few things.

1) Six replicates is a very small sample size; this could be a spurious, unlucky result. There is always some distribution of growth rate, even in a uniform genotype. Did I get unlucky and happen to put six plants that would always be on the smaller end of that distribution into SUPERthrive?

2) After analyzing the data, I discovered that four of the SUPERthrive plants ended up in the same row and were the smallest heads in the experiment (sometimes you flip a coin and get four heads in a row!). Could this be the reason for the unexpected results? The other two treated plants were in the other two rows, but neither was as large as the smallest control plant.

3) I do not have a perfectly controlled environment like one would find in a lab or even in a larger growing facility. However, something marketed with such aggressive claims of amazing plant health benefits and vigor should give a noticeable effect under a variety of imperfect, real-world conditions, such as those one would find in a home garden situation, don’t you think?

4) Perhaps my plants were already growing at their maximum potential and there was nothing for SUPERthrive to “improve.” Afterall, hydroponics indoors is already a relatively stress-free environment, as the SUPERthrive manufacturer also points out. Then what do they think their product is improving in hydroponics? Would I have seen an effect under less-than-ideal or more stressful conditions then? This could certainly form the basis of other testable hypotheses.

Conclusions

What I think we can conclude is that in this experiment, with this genotype of lettuce, and under these hydroponics conditions and environment, SUPERthrive had no positive effect whatsoever and may have even had a negative effect. Under other conditions would one see a positive effect? Possibly. Would different plants or genotypes respond to the SUPERthrive differently? Possibly. We must always be careful of over-extrapolating both positive and negative results from a single experiment.

But, because the individual ingredients have not been shown to provide any beneficial effect, and no plausible mode of action is given by the manufacturer for their broad general claims, we should remain highly skeptical. As pointed out in the previous post, the SUPERthrive manufacturer has certainly had plenty of time to scientifically demonstrate efficacy of their product, since they proclaim to be “always ahead in science.”

Because the results showed a clear and unexpected negative effect, the experiment surely needs to be repeated. Repetition is a central tenet of science. I hope to share additional results with you in a post later this spring—after all, I have a whole bottle of SUPERthrive and we love salad!

References

Banks, Jon & Percival, Glynn. (2012) Evaluation of Biostimulants to Control Guignardia Leaf Blotch (Guignardia aesculi) of Horsechestnut and Black Spot (Diplocarpon rosae) of Roses. Arboriculture & Urban Forestry. 38(6): 258–261
Banks, Jon & Percival, Glynn. (2014) Failure of Foliar-Applied Biostimulants to Enhance Drought and Salt Tolerance in Urban Trees. Arboriculture & Urban Forestry 40(2): 78–83
Chalker-Scott, Linda. (2019) The Efficacy and Environmental Consequences of Kelp-Based Garden Products.
Yakhin Oleg I., Lubyanov Aleksandr A., Yakhin Ildus A., Brown Patrick H. (2017) Biostimulants in Plant Science: A Global Perspective. Front. Plant Sci., 7:249

Tiny plants that pack a flavor and nutrition punch: getting in on the microgreen trend

If you do any searching for gardening (or even think about the color green), you’re likely bombarded with adds on social media and search engines about all stuff gardening. One of the recent trends is microgreen production. There’s all kinds of fancy little systems and gizmos that will help you grow microgreens for a price. But what are microgreens? Are they the same thing as sprouts? And do they have the same food safety issues as sprouts? Let’s discuss, shall we?

What are microgreens?

Microgreens are basically tiny plants harvested shortly after germination. Unlike sprouts, like the common alfalfa or bean variety, these baby plants are grown on a medium of some sort and just the “above ground” portion of the plant is harvested. Sprouts, on the other hand, are typically grown in a moist environment without a medium and harvested whole -roots, seed, and all. It is this wet and warm environment that make sprouts especially risky for food borne illness.

Microgreens can be any number of different crops, but common types are kale, mustard, chard, broccoli, arugula, and radish. Sunflower and pea are also common, but they fall more in the “shoot” classification since they are harvested a bit larger. There’s lots of other crops that are used for microgreens, including herbs like cilantro and even marigolds, so the sky is the limit!

Why microgreens?

There are a few things that make them attractive to farmers which also are good for home growers. First, it only takes 1-3 weeks for a finished crop. This fast turn-around makes it easy to keep up with production needs for customers (or your own uses) and also reduces risk. If a crop fails, it is much less damaging if it only took a week to grow rather than a whole field full of peppers that have been growing for months getting wiped out by disease or a storm.

Second, is the value and profit. While there is some investment in seed starting equipment and then continued expenses of seeds, trays, and media, microgreens have a high per pound value. Microgreens are used in small quantities and are therefore sold in small quantities. A small amount you may purchase at a farmers market for a few bucks may be an ounce or less. When you calculate it out by the pound, microgreens are sold for between $20 and $200ish per pound (depending on the variety, organic production, other factors).

And of course, microgreens lend themselves to year-round production. It can be a fun and easy way to get some flavor and color on the plate even in the dead of winter. Just a few square feet of production area can provide a decent sized crop, so it is great for those with limited space or no garden at all.

Look ma….I made fancy mac and cheese. All I had to do was add some microgreens.

Microgreens are popular with home cooks and chefs alike because they pack a flavor punch and add some color and texture with just a pinch or two of product. Studies have shown that microgreens also pack a nutritional punch in a small package. However, production practices can greatly influence nutrient content, especially light. Microgreens grown with higher quantities (brightness) and quality (spectrum colors, mainly red and blue but also green) of light have higher nutrient values.

How do you grow microgreens?

The way you grow microgreens lends itself to why they are so popular to grow, for both home enthusiasts and farmers alike. Microgreens are basically recently germinated seedlings. If you are good at seed starting, you can be good at growing microgreens. Lots of the ads I’ve been seeing recently are for attractive but pricey growing trays and mats that you just lay down and water. However, budget conscious gardeners can grow them pretty simply and inexpensively at home. And you probably have most of the equipment you need, especially if you start your own seeds each year!

Microgreens are usually grown in those flat plastic seedling trays, the type that don’t have cells in them (the ones used to hold the cell packs). For those “in the know,” they’re called 1020 trays. You can either use a sterile media like peat or coir or purchase specific fiber mats (I have some made from hemp -they work well but smell like a moldy gym sock full of weed when in use). We’ll talk about the importance of a sterile media when we talk food safety.

A demonstration of sowing microgreen seeds on hemp fiber mats.

The sowing density of seeds can vary by crop due to seed and seedling size. Typically, one ounce of seeds can sow anywhere from one to eight 1020 trays. In general terms, large seeded crops like chard and beets may take up to ½ cup per tray and small seeded crops like radish or kale might require ¼ cup. Tiny seeded crops, like sorrel may need just a few tablespoons. If you’re really into production, Penn State extension has an excellent Excel calculator to calculate seeding rates. Typically, you’ll broadcast the seeds on top of your media and then maybe sprinkle a little more media on top to make it easy (no dibbler here!).

Most seeds require darkness to germinate, as well as high humidity. You can use humidity domes and cover trays with an opaque material to achieve this, or you can use the trick that producers use and stack trays on top of each other for a day or two. This keeps the seeds covered and dark and preserves moisture and humidity. Just unstack them after a day or two and stick them in their growing location. As with seed starting, you’ll have the most success if you provide some good quality light and heat. (You can search through old articles to find lots of info on seeds starting). There’s research that shows that light is a big factor in microgreen growth, coloration, and nutrition levels.

You’ll harvest your microgreens typically one two three weeks after sowing. Typically, this is done after at least one set of true leaves have formed, but you can usually let them go until there are at least two (or sometimes three) sets of leaves. To harvest, use a sharp, cleaned pair of scissors to snip the seedling off just about soil level, being sure not to disturb the media so that you don’t get it on your precious produce.

There should be no need to wash the microgreens right after harvest and before storage, since they’re typically grown in a clean environment. Washing before storage can increase storage moisture to levels that support microbial growth, reducing storage time and also increasing the risk of human pathogens. Instead, store microgreens (and most leafy greens) without washing and wash just before use.

Working with a local farmer to demonstrate microgreen production at a regional production conference.

Food Safety

As we learned when discussing what microgreens are and comparing them to sprouts, we learned that microgreens have been found to have much lower risk of human pathogens. However, the risk is not zero, especially if production practices are conducive to pathogens. We just discussed that washing prior to storage can lead to microorganism contamination, but there are a few other areas where contamination is easy. To reduce contamination, follow these steps:

Always use clean and sanitized trays or containers. If reusing trays, be sure to wash with soapy water then sanitize with a dilute bleach solution or other approved sanitizer.
Keep the production area clean and sanitized. Microgreens are often produced on multi-leveled vertical racks, so contaminants can drip down. Make sure all surrounding surfaces are clean.
Use sterile media for production. This is typically a soil-less media made primarily of peat or coir, like a seed starting mix, or specialized fiber growing mats. Do not use regular potting soil, any mix containing compost, or anything containing soil to avoid the introduction of human pathogens or other microorganisms that might affect the crop, such as those that cause damping off.
Use cleaned and sterilized seed. Many companies sell seeds specifically for microgreens that have been processed to remove pathogens. I’ve seen seed production, and while it isn’t filthy, it typically isn’t sterilized to the level of food production standards. You can sterilize common seed at home using a solution of hydrogen peroxide or vinegar. For guidance, visit this guide from K-State extension.
Use a clean source of potable drinking water. If you wouldn’t drink it as is, don’t use it. Typically this means it should be straight from the tap of a trusted source.

Conclusion

Growing microgreens can be a fairly easy and enjoyable way to produce something fresh and green year round. In terms of production practices, it is basically ramped up seed starting where your seedlings only grow a few weeks before harvest. This makes it a fairly easy process and one that can be done almost anywhere. If you’re looking for an indoor gardening project or just want to add a quick source of nutrients to your diet, give microgreen production a try.

Sources and resources:

Microgreen nutrition, food safety, and shelf life: A review

Microgreens and Produce Safety

Microgreens—A review of food safety considerations along the farm to fork continuum

A step-by-step guide for growing microgreens at home

Planning Ahead (in a pandemic) for Vegetable Garden Success

Looking back to January 2020, most of us would have never imagined the year we’ve had. All of our best laid plans went away and instead we socially distanced, scavenged for toilet paper, and canceled events and vacations. But one thing that wasn’t canceled was gardening. By June, garden retail sales had increased 8.79% over the average, a big jump for a trend that was already showing increased gardening over the last few years. Wanting to grow food to ensure a safe food supply was one reason gardening increased this year, but it also served as away for people break the boredom of being stuck at home.

One bit of advice that we in Extension always give to gardeners, young and old, is to plan ahead, especially if they are growing fruits and vegetables or starting their own seeds. Given that rapid increase in garden sales, many would-be gardeners were frustrated to find the seed racks and plant shelves empty and online catalog retailers out of stock. From personal experience, I can tell you that white beets don’t look quite as pretty in the jar as those bright red ones. Given the fact that the pandemic is likely to continue well into 2021, it would be a good idea for those thinking about gardening to plan ahead on what they want to grow and plan to buy seeds and supplies early. This not only helps you plan out what you want to grow and when to start or plant it, but will also help you beat the rush and get the plants or varieties that you want.

Here are some things to consider while planning for your vegetable (or other) garden:

What are your garden goals? Are you wanting to harvest for fresh eating only? Hoping to preserve harvest for later? Have extra to sell or give away? Figuring out what you hope to accomplish will help you plan out how to use your space most effectively. Plan to plant extra of stuff you plan to preserve or give away, and plant it all at the same time to have a larger harvest. If you’re focusing on fresh eating for just your family, planting smaller quantities of each plant and spacing them out over time would be better.
What do you enjoy eating or growing? Focus on the crops that you and your family like to eat, especially if you have limited garden space or time.
What resources are you willing to commit to gardening? How much money do you have to invest in seeds, plants, or supplies? And how much time do you have to spend per week? You should base your garden size on what you can reasonably support. And also look for investing in efficiencies. For example, adding drip irrigation will be an investment of time and money up front, but will save on water bills and time spent watering the garden and will likely increase your harvests so it can have a pretty decent return on that initial investment.
Are you planning on growing throughout the garden season? Many people focus on gardening May through September and often miss those very productive early spring and fall months when cool season crops flourish. Making a plan for using space effectively can include growing an early season, summer, and late season crop all in the same spot using interplanting or succession planting. If you aren’t sure what to grow when in your climate, look for local growing guides or calendars to help. Your local Extension office will likely have some good resources to share. Having an idea what you want to grow throughout the season will also help you make early purchases to ensure you have what you need throughout the season. Seeds are usually off the store shelves by mid to late summer, so buy seeds in the spring for those fall and late planted crops just to be prepared.
Are there things you want to grow that would be easier to buy? This question is especially important if you have limited space, time, or money. Crops like potatoes, cabbage, and onions are often cheaper for home growers to buy than grow and crops like squash can take up a lot of room and are often easy to buy (there’s usually plenty of zucchini everywhere in the summer). Focus on those things you can’t buy like interesting varieties of tomatoes, peppers, etc.
Are you ready to deal with diseases and pests throughout the garden season? Be ready to scout the garden for pests and do a little research on the common pests and diseases on the crops you’re growing so you know what to look for. You can often reduce the likelihood of pests and diseases by growing newer resistant cultivars versus older varieties and heirlooms that don’t have resistance bred in.
What has worked (or not worked) for you in the past? Focus on growing those things you do well. Take some time to research or learn how to better grow the things you haven’t grown so well in the past (extension resources are great for this- contact your local office or search for info online, looking for pages that end in .edu). And don’t be afraid to try something new – you can find new favorites by trying out new cultivars or even new crops.

Using some of these steps can help you plan ahead for a year of garden success. The key is to start early, and especially in 2021, buy those seeds and supplies early. When you do, take a look at your plans for the whole garden season and plan accordingly in advance. Though while you’re out there buying those seeds, be sure to leave a packet or two on the rack for me. I’d prefer to have red beets for pickling this year instead of those white and yellow ones.

Hydroponics for the Holidays? Home Systems are a hot holiday gift list item

Systems to grow fresh produce in your home using hydroponics or other automatic processes have been popular for several years but seem to be even more popular this year with more folks home and looking for something to do and hoping to produce their own food. As a result, these systems are popping up on holiday wish lists and gift buying guides all over the internet. But are they worth it? And if so, what should you look for in a system?

First off, what are these systems? And what is hydroponics? Hydroponics is the process of growing plants without soil in a aqueous nutrient solution. Basically, you provide all the nutritional needs of the plants through nutrient fertilizers dissolved in water. These systems can grow plants faster and in a smaller space than traditional soil-based production. It also allows you to grow plants indoors and in areas where you would not normally be able to grow.

This Aerogarden (which is the previous generation) has a digital brain that controls light and water schedules for the specific growth phase of the plant and yells at you when it thinks you need to add more fertilizer solution.

As for systems, you might have seen what is probably the “oldest” one on the market – the AeroGarden. Since it is the oldest and most common, that’s the example we’ll be staying with. It has been around a few decades and has evolved from a basic electronic system to fully automatic, “smart”Bluetooth connected systems that you can control with your phone. In recent years there have been many new systems come onto the market at all different sizes and price points. A quick search of online retailers will usually provide an array of options – from DIY kits to plug-and-play enclosed systems such as “Click & Grow” and “Gardyn”. My only experience is with the Aerogarden system, so I can’t speak to any of the others (though I’d love to try them out!).

The answer to “are they worth it” is up to you, really. Most home based hydroponic or aeroponic systems offer convenience, but at a cost. Most cost several hundred dollars and are small, so they produce a small amount of produce (or other plants) at any one time. So you have to determine what goals you, or your intended giftee, have with the system.

“Baby” lettuce, 18 days after sowing. The current version of this 9-plant Aerogarden system, called the “Bounty”, retails for $300 but you can usually get it for under $200 on sale.

The benefit of the “plug-and-play” enclosed systems like the AeroGarden is that basically you can take it out of the box, set it up in less than 10 minutes, and have some fresh lettuce or herbs in a few weeks. It controls the water cycles, lighting, and all other conditions for growth. You just drop in pods that contain the seeds suspended in a spongy-material. The smallest system, that holds 3 plants, retails for $100. As an additional expense comes from buying refill kits to replant. The mid-size systems are the most common and range from $150-$300. The largest system, the “XL Farm” retails for $600. But these systems are commonly on sale at pretty significant discounts.

For many systems, you typically buy a new set of pods (there are different plant variety selections), but there are pods you can buy to assemble your own using your own seeds. For the AeroGarden, the pod kits range from $15 up to $30 to grow up to 9 individual plants. There are other plug-and-play systems on the market, as well as some kits that are more build-your-own and less automated.

No matter which systems you buy (or gift), keeping these costs in mind is important. If you’re looking for a fun and easy activity with the benefit of a little fresh produce and aren’t as concerned with production costs these systems may be for you – and if you are giving or getting them as a gift that definitely makes it more economical. But given the cost of the plug-and-play systems and the refill pods, they will never be an “economical” option for producing your own food. If you are wanting to produce food on a budget and you’re interested in home hydroponics, look for plans to build your own or buy a DIY kit.