Cover Crops: The Solution to the Problem You Didn't Know You Had
Ugh, the cost of fertilizer; Am I Right!?
One of the hardest things about organic or regenerative growing practices is watching people use synthetic fertilizers (think Miracle-GRO) and seeing their plants BOOM. But at the end of the day, we know two things: 1) it's just not healthy. Not for you, not for the soil, not for our water supply, etc. 2) They're going to have to ditch that soil and start over next year because it's going to be completely depleted once their plants suck all of the "food" out of it.
Here's the thing: the healthiest plants come from the healthiest soil. Healthy soil is alive, and the choices you make in your garden affect the soil health. Every teaspoon of your soil should contain billions of microorganisms: fungi, nematodes, bacteria, insects, earthworms, you name it. These organisms create the ecosystem in your soil.
Bacteria and fungi break down dead matter to become nutrients for the plants. Nematodes eat plant material and other organisms, feeding your plants with their waste. Mycorrhizal fungi have a mutually beneficial relationship with your plants; they bring nutrients and water that your plants can't reach to the roots, and then the plants feed them with carbohydrates. And worms and insects will eat organic material or break it down into smaller pieces to feed the bacteria and fungi. Worms will aerate your soil, creating pockets that fill with air and water that feed the organisms and plants.
So, naturally, if we add synthetic fertilizers to our soils, we definitely feed our plants, but that food is only temporary. It not only adds nothing to our soils, but it starves it. So how do we feed our soils in a way that is both sustainable and regenerative? We amend the soil.
One of the most common ways to amend our soil is to add organic material. Compost is organic matter that's been decomposed. The decomposed material becomes available to the plants, and then the plants feed the microorganisms living in the soil that's been amended by that compost. It's a super important thing to add to our gardens, and it's easy to make! We can create compost out of our grass clippings, fallen leaves, food scraps, egg shells, coffee grounds, and the plants we pull out of our gardens. This also reduces the waste we add to our landfills!
Compost needs to be added to our gardens regularly.
Here are some great resources to get started with composting:
This is the easiest way to amend our soil and feed the ecosystem that lives within it. It takes very little effort and it has some incredible results.
Cover crops slow erosion, increase yields, break up our soil, add organic matter, improve crop diversity, attract pollinators, smother weeds, improve soil health, enhance water availability, and help control pests and diseases. Simply put: you spread the seed over your soil, let it grow, and then turn it back into the soil before you're ready to plant in that area.
Not all plants are suited for cover crops; the ones that are suited for it provide specific nutrients and benefits and can be planted at different times during the year. Many commercial farms that use regenerative practices rotate their crops, utilizing cover crops when a section of their farm isn't being used. As home gardeners, we can use cover crops in between plantings, or even over the winter.
There are two types: legumes and non-legumes.
Non-legume types include buckwheat, oats, winter rye, barley, Sudangrass, tillage radishes, and different members of the brassica family. These types have fibrous root systems that reduce soil loss and take up the nutrients that leach out over the winter. And, because they grow so energetically, they suppress weeds.
Legume-types like crimson clover, hairy vetch, and cowpeas take the nitrogen that's in the atmosphere and put it into the soil so it can be used by future plantings.
Basically, a month before planting, you can cut back your cover crops and either turn them into the soil or lay them down to use as a mulch to continue suppressing weeds. They'll not only have fed the soil as they grew, but their decomposition continues to feed the plants.
When to Plant
Summer cover crops are planted in beds that you use for spring- or fall-only plants, like a lettuce, cabbage, or broccoli bed after those plants are pulled. You'd cut them before planting in that bed again. Buckwheat provides excellent weed suppression, but it must be cut soon after it begins flowering to avoid unwanted reseeding. The legumes cowpeas and crimson clover are good for summer, and can be planted together with non-legumes for weed suppression and added nitrogen.
Winter-kill cover crops are planted after summer garden crops are harvested, then killed by freezing temperatures. The following spring, you can plant early-season greens and veggies right into the resulting mulch. Winter-kill cover crops include oats, brassicas and field peas for USDA Zone 7a.
Overwintered cover crops are planted late in the season. You'd plant them in the fall, and then they'll survive the cold winter while suppressing weeds in that area. When chopped down the following spring, they make a great addition to the soil or work wonderfully as mulch. In Zone 7a, good overwintering crops are winter rye, hairy vetch and crimson clover.
How to Plant
To plant cover crops, you just hand-broadcast the seed over some soil and rake it in right before a rain. No rain in the forecast? Give it a good shower. Then, about a month before you plan on putting your plants in the soil, cut it down and lightly turn it in or use it as a mulch.
High Mowing Seeds has a great resource on cover crops, letting you know the benefits and planting advice for each type of cover crop: https://www.highmowingseeds.com/blog/keep-it-covered-how-to-choose-fall-cover-crops/
Cover Crops in Northern VA
For fall planting, I can highly recommend the mix that Sow True Seeds creates for overwintering. I actually prefer mixes; I've found that many experienced farmers have reported that planting a diverse mix of cover crops results in a diverse set of benefits. Makes sense to me!
I combine these two with wonderful results:
Sow True Seeds- Overwintering Mix: https://sowtrueseed.com/collections/cover-crop/products/over-wintering-mix?variant=6904735498282
Sow True Seeds- Raised Bed Mix: https://sowtrueseed.com/collections/cover-crop/products/raised-bed-mix?variant=6904756633642
One of the biggest game-changers for me, when moving from the sandy acidic gold of New Jersey to the Virginia clay, was cover crops. Hear me out.
There's this cover crop called Tillage Radish. It's known to break up your soil naturally while also feeding it. It suppresses weeds, grows quickly, finds nutrients and brings them to the topsoil, and reduces the compaction in your soil.
In late summer, you'd plant the tillage radish and then just leave them. Seriously, that's it. They'll die over the winter here in Northern VA, and then they'll decay and contribute to a nitrogen store for your spring plants. Dying off in the winter, the radishes leave root channels so that soil dries and warms up faster in the spring.
This article lays out all of the benefits of tillage radishes, and also gives other recommendations for cover crops that lesson soil compaction that would complement our gardening practices: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_022940.pdf