Did you know that you can email me directly if you go to the ‘contact me’ page on this website? I would absolutely LOVE to answer any question you have, and if I can’t answer it, I’ll be honest about that, too. It’s all too obvious that I am running out of things to write about. When I was taking Horticulture classes, I was always learning something new about gardening, or trying experiments out in the lab, and I had lots of information to share. Then I swerved briefly into more general science classes, which still had some good, relatable info. But now I’m fully into my upper division courses, which are all for my Environmental Studies degree and include boring things like data collection and carrying capacities and population control and clean energy. Well, they aren’t boring to me, but they certainly aren’t the focus of this blog, and aren’t as fun to read about as bugs and vegetables and flowers. So I really appreciate questions! They give me a chance to write about fun things and to question my knowledge and opinions of them and of course, that way we can all learn together, which is my favorite thing of all.
This morning I got a wonderful email from a reader named Jill, who lives not far from me: “ I sadly lost most of my garden due to the heatwave and an irrigation issue. I’m looking at cover crops and know nothing about the subject. Do you have any tips or links to places you buy the seeds from. Maybe some simple do’s and dont’s? “ Thank you Jill! Thank you for reading the blog and thank you for this question and thank you for your faith that I can answer it!
Buckwheat, a summer cover crop in warm climates
Cover crops can seem intimidating and confusing, so let’s start from the beginning. What is a cover crop? The simple answer is that a cover crop can be anything you want it to be. The Oxford Dictionary definition is “any crop grown for the protection and enrichment of the soil.” Farmers tend to use specific plants to satisfy specific requirements, which can be very important, especially if you want to grow without inputs i.e. chemical fertilizers. Some plants provide nitrogen, some phosphorus; others attract beneficial insects, and still others provide biomass for feeding animals. Some are grown during the summer, and some are grown during the winter. Some are grown after a specific cash crop, to replenish certain nutrients.
If you’re a farmer, and you’re making a living growing and selling your crops, you’re going to want to know a lot more details about cover crops and how they can be used to save you money. But if you’re a regular home gardener, your needs are different. You want something to improve the soil, attract beneficial insects, look pretty, and feed your compost pile when it’s done growing. Maybe you want to avoid buying soil amendments this year (they’re going to be hard to find, considering how many people are gardening for the first time). Maybe you don’t like the structure of your soil, and you want to improve its water-holding capacities. Maybe you like birds, and you want to feed insects that will in turn become food for the birds. These are all fine reasons to grow a cover crop.
The thing that is most important is that you have a living root in the ground at all times. Now, if you live in upstate NY, you know that eventually that root will likely die, and that’s the way it’s supposed to be, and maybe even you time a crop so that it winter-kills and you don’t have to cut it down yourself. If you live in California, however, you can grow different cover crops at different times of the year, year-round. Having a living root in the ground is what improves your soil. The plant harvests sunlight, makes sugars, and pumps those sugars down into the roots and into the soil. This attracts microbiota, tiny creatures that feed on the sugars that the plant provides. In turn, they poop, providing micro-manure to the soil, and they burrow, improving air flow to the roots, and they die, recycling nutrients, and they move a ton of soil, making it rich and crumbly and perfect. If there’s no root in the soil feeding the microbes, then they move on or die off (or become very, very sluggish, waiting for the next influx of food). It’s not the plant that is feeding the soil, it’s the animals that are feeding the soil - the bacteria, fungi, protozoa, and nematodes - the primary and secondary consumers. When you spread manure or compost on the soil, it doesn’t feed the plant - it feeds the soil life, which in turn form these associations with the plant roots and provide the nutrients the plant needs to thrive.
image credit: center for food safety
So if you look at it this way, any plant can be a cover crop. No matter what kind of plant it is, it is going to continuously pump sugars into the soil and feed soil life, therefore improving your growing medium.
However, some plants need a lot of nutrients. If you’re planning a summer garden full of squash or melons, for instance, you might want a high nutrient load in the soil before you plant them. Why not grow a crop that will also add specific nutrients to the soil? Here is a handy chart, provided by the Organic Growers School, to help you determine which crop you need at which time.
image credit: the Organic Growers School
Don’t worry too much about the seeding rate. I just spread it on thickly, and that does the trick.
I’ve grown many different specific cover crops, and I tend to stick to two - crimson clover in the winter, and buckwheat in the summer. Some years I don’t use them at all. Some years I plant them intercropped with other plants that I am using for food. Some years I grow them alone in specific beds. They’re both great, but both require cutting and removing before they set seed (at least here in CA), or else they will seed everywhere (which is not the worst thing in the word). I’ve also done several mixes, especially in summer, that combine many species to provide many different nutrients. This is actually proving to be best for the soil, generally. If a living root in the ground is good for the soil life, then a wide diversity of roots in the ground would naturally be even better. I’ve also grown winter wheat and oats, which provided me with the best variety of beneficial insects I’ve ever seen in my garden. Long grass is apparently second only to a pond for attracting wildlife, and we saw that firsthand.
Many seed houses sell cover crops, but the best place I’ve found is Walnut Creek Seeds in Walnut Creek, Ohio (I know, it’s a coincidence that my town is also named Walnut Creek). They’re super-friendly, the farmer (Dave Brandt) has pivoted his business from growing corn and soy to growing cover crops, and he is also involved in a lot of research with the NRCS to show how cover crops can save money for traditional farmers, improving crops, soil, water levels, and erosion. Their prices are incredibly reasonable. They also sell specific gardening mixes for the home grower. I’ve used both the summer and the winter mix, and can vouch for them. Mr. Brandt is also one of the first conventional farmers to help develop special seeding equipment to enable farmers to plant their cash crop directly into the residue from a cover crop. He has a lot of videos on his website, and I think they are fascinating. (I have also ordered phacelia from them, by the pound, for early spring seeding in my pollinator gardens. The bees go crazy for it.)
If you’re interested in how soil can be a huge catalyst to improving our planet (and some history on how it’s disappearance has contributed to societal failure), an excellent book is Growing a Revolution: Bringing our Soil Back to Life, by David R. Montgomery. If you’re looking for a nice film to help you understand these concepts, look for Symphony of the Soil, which came out years ago and is still one of the best films about soil I’ve ever seen. For a crash course on soil health and how cover crops can be used to improve your land, you can’t do better than Living Web Farms’ series with Roy Archuleta and Dave Brandt - these videos will blow your mind.
If I were Jill, and my garden had been decimated by heat and smoke (mine is pretty sad too, sister!), and if I wasn’t planning on winter food crops, and I wanted to improve the soil, I would plant buckwheat right now. It’ll grow and flower quickly in our late summer/early autumn heat; it’s quite a pretty plant, with lovely tiny white flowers. Around late October or early November, I would cut it down and lay it on top of the soil where it grew. This will provide cover for the soil over the winter. (Studies have shown that it’s better for the soil if you just lay the residue on the top, rather than turning it under.) Or, you can add that residue to your compost pile. I would then plant either a winter mix of grain, clover, peas, and radish (or the mix Dave sells) right into those same beds, and let it grow a bit before the real winter hits us. When it begins to warm up again in January/February, that cover will take off and grow like mad, and you can let it go until you are ready to cut it down and plant your spring crops. This will do wonders for your soil, and you will also be feeding pollinators: Both now, with the buckwheat, when it’s hot and crispy outside and there’s not a lot to eat, and early in spring, when the bugs are emerging from their winter dens and need nutrition, pronto.
Do any of you use cover crops regularly? What’s your experience with them? Do you have any tips for Jill (and the rest of us)? If so, please leave a comment down below. Good luck, Jill! Let me know if you have any more questions.