Cover cropping is a strategy used by many growers, both large- and small-scale, to improve the soil without the use of chemicals. Cover crops offer your garden many benefits, ranging from reduced erosion and compaction to increased fertility and soil organic matter, and different types of cover crops serve different purposes: Legumes, for example, boost nitrogen in your soil while root crops break up heavy soils. Although cover crops don’t traditionally end up on the dinner table, every bit of space matters when gardening on a small lot, so consider selecting your cover crop for a secondary purpose, like food or herbal remedies. Here are a few cover crops that can do double-duty, enriching your soil while putting food and herbs in your kitchen.
Cover-crop Purpose: increase soil organic matter, suppress weeds, attract pollinators and beneficial insects
Double-duty Use: buckwheat groats to use in porridge or to grind into flour
How to Grow: According to author Sara Pitzer in Homegrown Whole Grains (Storey Publishing, 2009), plant buckwheat two to three months before your last-frost date to ensure it goes to seed before the frost kills it but that it doesn’t go to seed during the hottest weather. It likes to grow where it’s warm and sunny in acidic sandy or loamy soil, though it will still grow under less ideal conditions.
Use a broadcast spreader to plant seeds in weed-free soil at a rate of about 1/4 pound per 100 square feet. Rake over the soil to lightly cover the seeds.
Harvesting for Food and Soil: Harvesting buckwheat groats—aka, the seeds—while keeping the buckwheat plant for its cover-crop benefits is a challenge. If you were harvesting buckwheat primarily as a food crop, you’d cut down the whole plant and remove it from the garden. But in this case, you want to harvest just the seeds and leave the whole plant in the garden so you can incorporate the plant into the soil as a green manure. In Small-Scale Grain Raising (Chelsea Green Publishing Company, 2009), author Gene Logsdon says you can strip the plants of their seeds just using your fingers. This is a doable method for small harvests but can become pretty tedious if you are after something more than a few quarts at a time.
Watch Out! Buckwheat is prolific, so allowing the cover crop to go to seed means some seeds will drop and create volunteers that will need to be weeded out the following growing season.
2. Red Clover
Cover-crop Purpose: fix nitrogen, break up heavy soil, raise soil organic mater, suppress weeds, attract pollinators and beneficial insects
Double-duty Use: red clover blossom tea (considered a blood purifier)
How to Grow: Red clover grows well in regions where corn thrives and it prefers cooler conditions. Plant it in well-drained, neutral-to-acidic (6.0 to 7.2 pH) soils by broadcasting the seed and covering the seed lightly with soil using a rake. Use 1/4 pound of seed per 1,000 square feet.
Harvesting for Food and Soil: Harvest red clover flowers early in the morning, while they are still wet with dew. Dry them on a screen or hanging in a dry place. Only the flowers are used in herbal medicine, so the rest of the plant will remain in your garden as a cover crop. If you can wait to incorporate red clover into the soil until mid-bloom in the spring of its second year, you’ll get the most nitrogen in the soil, but you can till it into the soil as green manure at any time and still see benefits.
Watch Out! Once red clover has been pollinated, its flowers will start to die. Harvest flowers when they are in full bloom but don’t have any brown areas.
3. Daikon Radish
Cover-crop Purpose: break up soil, suppress weeds, add soil nutrients, lure flea beetles away from other crops
Double-duty Use: daikon radishes and radish greens
How to Grow: Plant a daikon radish cover crop at a rate of five seeds per square foot so the radish greens can shade out weeds. Broadcast seeds and lightly cover them with soil using a rake.
Daikon radishes can tolerate light frosts but nothing colder, so plant with an eye on your variety’s days to maturity and your area’s first-frost date. They need to grow at least six weeks to be a beneficial cover crop.
Harvesting for Food and Soil: With daikon’s 1-foot-plus taproot drilling into compacted soil, this radish’s primary cover-crop function is soil aeration. Once the radish is grown, it can be harvested and eaten. Grasp the greens at the top of the root, and pluck the root from the ground. Leave unharvested radishes in the garden to continue to provide their other benefits, and incorporate these before you’re ready to plant in that space again.
Watch Out! If harvested when too old, daikon radishes can be woody and bitter. Pay attention to the days to maturity on your seed label. Also, rotting radishes are stinky, so if you have a freeze and then a warm thaw, you might need to do some fast garden cleanup.
4. Canadian Field Peas (or Spring Peas)
Cover-crop Purpose: fix nitrogen, build soil organic matter
Double-duty Use: young pea shoots for salads and steaming
How to Grow: Field peas like a cool growing season and are frost-tolerant. They can grow in well-drained, mildly acidic (pH of 5.5 to 6.5) soils.
Harvesting for Food and Soil: Young pea shoots can be harvested for eating pretty much as soon as they appear large enough to eat. They will become tough with age, so get them before they reach 8 inches. One to two weeks before planting again in that area, mow and till the field peas. The Cornell University Cooperative Extension says this time frame will prevent nutrients being tied up while the peas are being incorporated into the soil.
Watch Out! Do not plant field peas as a cover crop in close rotation with other legumes because field peas are especially susceptible to root rot nematodes.
Don’t leave cover cropping to the rural farmers. Urban soil can benefit just, as well. With careful variety selection, you can get the most from your garden’s cover crop.
About the Author: Freelance writer Lisa Munniksma is learning about cover crops for her small-scale herb plot. She blogs weekly about ag news and opinion for HobbyFarms.com and blogs about her own traveling and farming around the world at www.freelancefarmerchick.com.