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.)

Figure 1. Outline of 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

  1. 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
  2. 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
  3. Chalker-Scott, Linda. (2019) The Efficacy and Environmental Consequences of Kelp-Based Garden Products.
  4. 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:

  1. 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.
  2. 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. 
  3. 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.
  4. 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. 
  5. 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.
  6. 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. 
  7. 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. 

The complicated issue of heavy metals in residential soils, part 1: What are toxic heavy metals, and where do they come from?

The popularity of home gardens is exploding as we wait out the COVID pandemic

So many of us are growing our own vegetables – either as experienced home gardeners or as COVID19-isolated novices. There is a lot of effort in figuring out garden beds, vegetable choices, and growing medium – but one of the issues rarely considered is whether there are heavy metals present in the local soil and/or growing medium. We can’t see heavy metals, or smell them, so we need to have a way of assessing their presence before we plant edibles.

In the next few months, I’ll tackle the complicated science behind this invisible threat. Today, let’s look at the heavy metals that are commonly found in garden soils and where they might come from.

What heavy metals do gardeners need to monitor in their soils?

Heavy metals are exactly that – they are dense elements that have certain chemical properties that define them as metals. In fact, most known elements are considered to be heavy metals. Fortunately, there are only a handful of heavy metals that are commonly found in residential soils. Some of these heavy metals are necessary for life – iron, manganese, and zinc, for example – but others have no known biological function. Arsenic and lead, for instance, can interfere with enzymatic activity and effectively poison biochemical pathways. There is no “safe” level of heavy metals that are not essential nutrients.

Here’s a table of the most common toxic heavy metals that might be found in your soil, and possible anthropogenic sources:

Heavy metal Sources of contamination
Aluminum* Smelting
Arsenic Pesticides, smelting, treated timbers (old)
Cadmium Paint
Chromium Fly ash, metals industry, paint, leather tanning, treated timbers (old)
Lead Gasoline (leaded), paint, pesticides, plumbing, smelting, solder
Nickel Plumbing, smelting

*Aluminum is a light metal, not a heavy metal, but has similar biochemical poisoning activity as toxic heavy metals

Some of these sources of contamination are not relevant to where I live – why do I need to test my soil?

Gardeners may be tempted to look at the chart above and feel relieved, because pesticides and paint no longer contain heavy metals, they don’t use old treated timbers, and they know that leaded gasoline is a thing of the past. What many don’t consider, however, is that heavy metals are elemental – they don’t break down, though they may change their chemical form. They are a permanent part of soil chemistry unless they are removed by physical or biological means.

The underlying soil in housing developments built on old agricultural land often contains high levels of arsenic – because that was the active ingredient in pesticides many decades ago. If the topsoil was removed during construction, it may have been taken to a commercial soil facility where it would have been used to create landscape fill mixes for new landscapes elsewhere. The same is true for land near older roadways where lead from gasoline was released from vehicles over many decades. Not only are lead, arsenic, and other heavy metals in the soil, they also end up in the air when soil is disturbed by erosion or tilling.

Nearly all soils contain some level of some heavy metals. They are naturally occurring, after all, so their presence is not necessarily from anthropogenic activities. Regardless of the source, it’s important to know whether any of these harmful elements are in your garden soils, especially if you are growing edibles. A soil test is the only way to find out.

Here is a soil test of my own raised bed system. While my nutrient levels are optimum, and lead is very low, the aluminum level is quite high. What should I do?

Why aren’t there guidelines on heavy metal uptake in vegetable gardens?

It would be ideal if there was a list of “safe” and “dangerous” vegetables to plant when heavy metals are present. Unfortunately, real life rarely fits into lists and there are numerous sources of variability. Next month I’ll discuss the complications that arise when we consider plant species, heavy metals, and environmental variables.

Smashing Pumpkin Myths: Bleaching to extend shelf (and porch) life

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Scrolling through social media in September and October and you may see those basic signs of the season: scarves, pumpkin spice lattes, sweaters, and Halloween ideas galore.  One of those Halloween ideas is to extend the life of your pumpkins, carved or otherwise, by giving them a treatment with household bleach.  Keep scrolling and you might see another post decrying the use of bleach as inhumane and poisoning for wildlife.  So which is it?  Is bleach safe to use as a sanitizer on your jack-o’-lantern or are you poisoning the neighborhood squirrels?  Let’s use our gourd to explore the science.

The bleach acts as a sanitizer, neutralizing fungi and bacteria on the surfaces of the pumpkin that will cause decomposition and rot.  Even un-carved pumpkins will eventually succumb to degradation under the right conditions.  But if bleach kills fungi and bacteria, will it kill wildlife? The answer is – not if it is used correctly.  Bleach, and sodium hypochlorite (the active chemical in bleach) are toxic if consumed directly in concentrated amounts, however, dilute solutions break down quickly in the environment.  Products containing sodium hypochlorite, including plain household bleach, are actually approved and labeled for use as a sanitizer by produce farmers to reduce both human pathogens and decomposition microorganisms and extend the shelf life of produce that finds its way to the grocery store, farmers market, and any other avenue from the farmer to the consumer.  These wash water sanitizers are used more for reducing cross contamination of from pathogens introduced to the water from dirty produce, but it can reduce the microorganism load on produce items. If used correctly to sanitize the surface of the pumpkins, bleach DOES NOT pose an increased risk to wildlife (or human) health.

What is the proper way to use bleach in sanitizing that pumpkin so that it doesn’t face an early demise?

  1) Make sure the pumpkin is clean by washing with plain water or a mild detergent to remove any soil or debris.  Sanitizers like bleach are quickly neutralized (used up) on dirty surfaces (this is a good lesson for home cleaning, too – you cannot sanitize a dirty surface). 

2) Prepare a DILUTE solution of plain household bleach (unscented, and not “splashless”). The recommended concentration is 200ppm sodium hypochlorite, which you can achieve with 1 Tablespoon of bleach per gallon of water.

3) Apply the solution to the pumpkin using a spray bottle.  Alternatively, you can prepare enough solution to dunk the pumpkin(s) and immerse them in the solution.  If you are sanitizing a carved pumpkin, I would opt for the spray method – dunking may result in infiltration of the solution in to the exposed flesh. It will still break down since it is a dilute solution, but it will slow down the process since it protects the bleach atoms from air and sun exposure.

4) Allow the pumpkin to air dry.  Sanitation is not immediate (keep that in mind for sanitizing surfaces in the home, as well) and wiping can cause cross contamination

If I can do this with a pumpkin, should I be doing this with my other produce?

The short answer is NO.  It is not recommended that home grown or purchased produce be washed with any sort of detergent or chemical in the water.  Fresh cold water and friction should be sufficient for removing soil and pathogens on the surface.  Proper protocols, equipment, and training are needed to make sure sanitation is done properly. Knowing which produce items can and cannot be washed with a sanitizer is important. However, if you are harvesting produce like pumpkins or winter squash for long-term storage you may want to consider sanitation using the above methods.

I don’t want to use bleach, can I use something like vinegar?

There are many sanitizers approved for use by produce growers for sanitation, so bleach is not the only option.  For home consumers there aren’t so many options.  Vinegar is often mentioned as a wash for produce.  I found no direct mention in produce handling guides of using vinegar on pumpkin, but most produce wash solutions use vinegar at a much higher concentration because it is much less effective at sanitation.  I found rates ranging from 1/3 c vinegar to 1 c water to 100% undiluted household vinegar for use as a produce wash.

Sources:

Sanitizers Labeled for Use on Produce (Produce Safety Alliance)

Produce Wash Water Sanitizers (UMN)

Guidelines for the use of chlorine bleach as a sanitizer in food processing operations (OSU)

Saving for the Future: Seed Saving Tricks and Tips

As summer winds down and the summer crops and flowers start to slow down many gardeners start thinking about saving seeds. Who doesn’t love saving seeds from that favorite tomato or beautiful coneflower?  Not only do you have some for next year, but you can also share with your friends! There are definitely some things to consider and some myths out there when it comes to seed saving, so let’s talk about how to do it right. 

You’ll get the most consistent results from open pollinated or heirloom varieties that are self-pollinating.  These plants have genetics stable enough that the seeds you save will come out looking and acting like a close approximation to the plants from the previous season (with some variation based on your selection of the “best” plants you save seeds from. Self-pollinating species are: tomatoes, peppers, eggplant, beans, peas, peanuts (note, peppers and eggplants have more open floral structures that can be cross pollinated).  Most tree fruits like apples and pears are cross pollinated and they are notorious for not “breeding true” – even if you hand pollinate to ensure that the mother and father are both the same cultivar you’re likely to get surprises.  Stone fruits (peaches, plums, etc) are less variable but still not true-breeding.  Bee pollinated plants are also notoriously hard to save seed from, since they can cross pollinate with different varieties and cultivars from miles away.  It is especially interesting for plants that look totally different but are the same species (like pumpkin and zucchini).

A puccini – or a zumpkin? Either way, it was nasty.

Myth: You can’t save seeds from those new modified hybrid plants. They’ve been made to be sterile

First off, hybrids aren’t genetically engineered and there are no GE plants available to home gardeners (most home garden crops don’t even have GE versions).  Hybrid plants do in fact usually produce viable seeds.  However, you won’t get the consistent results you will with open pollinated/hybrid varieties.  Hybrids are the F1 generation of a specific cross between a mother and father plant.  The offspring from that F1 generation (the plants from the seeds you save) is called the F2 generation will be a mix of traits – some will look like the F1 generation, some will look like the mother, some the father, and some the milkman.  So you’ll be in for a mixed bag of surprises.  According to our former GP colleague Joseph Tychonievich’s book “Plant Breeding for Home Gardeners” you can even develop a stable open pollinated variety from hybrids by saving seeds over a few seasons, selecting seeds from the plants that most resemble the cultivar you’re trying to save. 

You’ll want to make sure that the fruit/flower head that you’re saving seed from is mature.  This can be tricky for some vegetables, because we eat them in their immature states.  Peppers need to change from green to whatever their color is (red, yellow, orange, purple, etc),  cucumbers and zucchini (and other squash) need to turn into those massive, bloated fruits that often change to yellow or orange.  Beans often need to change to yellow or tan (and may have stripes).  For flowers, the seed heads or fruiting structures often need to turn brown and dry or start to open. 

If the weather cooperates, you’ll want to collect seeds from dry fruits/structured (beans, some flowers, etc) before significant rainfall so that seeds don’t become wet and potentially mold or break dormancy.  Collect seeds and place in a warm, dry location to let them continue drying out (if they’re small you want to put them somewhere they won’t blow away).  After drying, store seeds in envelopes or containers and put them in a cool dry place.  I often tell people to store seeds in the freezer – the cold temperature slows down respiration in the seeds and can extend their lifespan (the fridge is too moist/humid).  If you do that, drop your envelopes or containers down into a sealable container or bag to help keep condensation minimal when you pull them out of the freezer next year.

For home gardeners, it may not matter that you get plants next year that exactly copy the ones you saved seeds from – the fun can be in the surprise.  Who knows, you may discover a new variety – at least one that is exciting to you.  It can be fun seeing the variation in your new plants and finding something that you love. 

Epilogue: A special case – tomatoes

Most of the vegetable crops we grow don’t need any special treatment to break their dormancy (you’ll have to research flowers on a case-by-case basis) – save the seed and plant it next year and it will pop up.  Tomatoes are a bit of a special case.  If you scrape the seeds out of the fruit you’ll notice they’re still covered with the “goo” from inside the tomato which is called interlocular fluid (interlocular = between seeds).  The coating persists on the seed even if you wash them.  It has long been held that this coating retains some of the hormones of the fruit (like abscisic acid) that inhibits germination (though not all experts agree). So many sources will tell you to go through some process to break down the coating left on the seed, most commonly by placing the seeds and associated goo in a container, adding a bit of water, and letting them ferment for a few days.  You can dump them out and wash off all the gunk. Whether or not this is required to break dormancy is up for debate, but it does provide you with clean seeds that you can store easily.  There is also some evidence to suggest that this fermentation process helps remove pathogens on the exterior of the seed (heat treatment can help remove interior pathogens as well).

Some people just scoop out the seeds and smear the goo on a paper towel and try to scrape them off next year.  Some people add the step of washing, but this will still not remove all of the goo coating the seeds. This works if you’re not trying to share (or sell seeds) since they will stick to the paper towel. My guess is that the in the day or so that it takes for the goo to dry there is enough fermentation or decomposition going on to break dormancy.  If you don’t want the seeds stuck to a paper towel, you can use wax paper or some other non-binding surface, but you’ll still have dried goo on your seeds.

Some like it hot… but most do not: How high temperatures delay pollination and ripening

Ah, summer – vacations (pre-COVID), swimming pools (pre-COVID), ice cream, vegetable gardens, and, in many places, really high temperatures.  These things all go hand-in-hand (or at least they did before the pandemic). Many gardeners feel that the heat of mid-summer goes hand in hand with garden production; those high temps driving production on those fruiting plants like tomatoes and peppers.  But…..could they be wrong? 

We’ve had lots of extra hot days this summer in Nebraska, so it stands to reason that we should have really great production on those garden favorites like tomatoes, right? Then tell me why our extension office has received numerous questions this year about why tomatoes aren’t setting on or ripening.  Heck, we even had a Facebook post about tomatoes not ripening in the heat go viral (well, for our standards – 300,000 views/2,000 shares).  Could it be a disease?  Nope – it’s the heat. High daytime temperatures can have a big effect, but the effects are compounded when nighttime temperatures are high as well.

Tomatoes not ripening? You're not alone. Temperatures above 85 degrees will slow down the ripening process. Temperatures above 95 can stop the process all together. #NebExt #NeWX

Posted by Nebraska Extension in Douglas-Sarpy Counties on Wednesday, July 22, 2020

It turns out that high heat does two things in many of those fruiting vegetables (and of course fruits) that we grow.  First, it inhibits pollen production, which in turns reduces fruit set.  Second, heat inhibits gene expression for proteins that aid in ripening/maturation of the fruit.  Heat stress also reduces photosynthesis (Sharkey, 2005) in many different plants, which would slow down plant processes (such as fruit development and ripening) as it reduces the availability of sugars to fuel these processes.  So high heat can not only reduce the number of fruits developing on the plant, but also slow down the ripening process for fruits that have already set.  And if you think that these effects only happen at super extreme temps, most of the research studying temperature effects of this nature use a common “high ambient temperature” of 32°C/26°C for daytime/nighttime temperatures. For us U.S. Fahrenheit-ers, that’s 89.6°F/78.8°F, which isn’t really all that hot for most of us.

Many studies show that application of this “high ambient temperature” to crops such as tomatoes, beans, and corn during the pre-fertilization phases of reproduction (ie – flower/pollen development) can negatively effect fruit set.  The introduction of Porch and Jahn (2001) gives a pretty good overview of literature detailing the effect in beans (Phaseolus vulgaris).  I’ll sum it up here: heat stress while the pollen is forming (called sporogenesis) led to pollen sterility and failure of pollen to release from the anthers (dehiscence).  It also led to flower abscission (basically the plant aborts the flower) and reduce pollen tube formation (how the pollen nucleus gets through the stigma to the ovule for pollination) when applied during the period of pollen sac and ovary development.  And application during flower opening (anthesis) resulted in pollen injury (sterility) and reproductive organ abscission.  All of these effects lead to reduced fruit/seed set in beans.  (Interestingly, heat stress at the ovary development phase also led to parthenocarpy – basically the pods developed, sans seeds, without fertilization). 

However, we get the most calls about tomatoes (they’re the top crop for most home gardeners).  Is it the same issue?  Yep.  Numerous studies (Sato, et al., 2000; Pressman, et al., 2002; Abdul-BAki, 1992) show the same effect in tomatoes.  Pressman, et al. (2002) linked the effects on pollen to changes in carbohydrates in the anthers (reduced starch storage and carbohydrate metabolism). 

Tomato pollination and how to increase it in high tunnels
Tomato floral structures

To add insult to injury, high temperatures also slow down or stop ripening of crops like tomatoes.  Picton and Grierson (1988) found that 35°C (95°F) temperatures altered the gene expression in tomato fruits – inhibiting the expression of polygalacturonase, which softens cells walls, allowing the fruit to ripen.  Reduced photosynthesis would also reduce the availability of sugars for fruit development and ripening.

But there’s hope, both this season and in the long term!  The effect on the plants is not permanent. When temperatures drop below that “high ambient temperature” threshold pollen production, and therefore fruit set, will return to normal (as long as the plant is healthy).  Sato, et al. (2000) found that pollen release and fruit set resumed within a few days after heat stressed plants were “relieved” and temperatures dropped back into the optimal range of 26-28°C/22°C (78.8-82.4°F/71.6°F).  So many of those plants will become productive again (good news for my own tomatoes and beans, which had an initial flurry of production then went on vacation), especially as we head into fall.  And efforts are under way to develop and test heat stress resistant cultivars. 

This last point may be more important than you realized.  These production problems plague many areas around he world at current climactic norms.  Many fear that increasing temperatures will limit the productive capacity of many areas of the world that are already struggling.  It is easy to see how the difference in just of just a few degrees can take your veggie production from prolific to paltry.

You can also try to reduce the heat a bit yourself for an immediate fix. Shade cloth can help reduce temperatures a little bit, which may make all the difference in your garden if you’re just slightly over the “high ambient temperature” threshold.

Tomatoes under shade cloth | Tomatoes under shade cloth | Flickr
Tomatoes under shade cloth | Source: flickr.com

But in the meantime, if your vegetable garden has taken a summer siesta it will get around to producing again one day.  You’ll just have to take good care of the plants in the meantime.  And perhaps it’s a blessing in disguise – when its that hot I don’t want to be out working in the garden much, either.

Sources

  • Abdul-Baki, A. A. (1992). Determination of pollen viability in tomatoes. Journal of the American Society for Horticultural Science117(3), 473-476.Porch, T.G. and Jahn, M. (2001), Effects of high‐temperature stress on microsporogenesis in heat‐sensitive and heat‐tolerant genotypes of Phaseolus vulgaris . Plant, Cell & Environment, 24: 723-731. doi:10.1046/j.1365-3040.2001.00716.x
  • Pressman, E., Peet, M. M., & Pharr, D. M. (2002). The effect of heat stress on tomato pollen characteristics is associated with changes in carbohydrate concentration in the developing anthers. Annals of Botany90(5), 631-636.
  • Sato, S., Peet, M. M., & Thomas, J. F. (2000). Physiological factors limit fruit set of tomato (Lycopersicon esculentum Mill.) under chronic, mild heat stress. Plant, Cell & Environment23(7), 719-726.
  • Sharkey, T. D. (2005). Effects of moderate heat stress on photosynthesis: importance of thylakoid reactions, rubisco deactivation, reactive oxygen species, and thermotolerance provided by isoprene. Plant, Cell & Environment, 28(3), 269-277.

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