What do you do with the bare ground after you've harvested your veggie garden? How can you perk up soil that's either too low in organic material, or wiped out by back-to-back seasons supporting heavy feeders? Is there a solution that won't require me to spend too much time away from Netflix?
Cover crops are fast-growing plants that suppress weeds, nourish the soil, and prevent erosion. Some are grown in between vine rows (like mustard in Napa Valley) while others are strictly used on a quick turnaround basis as "green manure," adding or subtracting minerals and nitrogen while improving the soil's tilth.
You might associate cover crops with large-acreage farms, but they're scalable to home gardens, too. Most of them are just as attractive as ornamentals, with lush foliage and charming flowers that might tempt you to plant 'em and leave 'em for the entire season. Even if you do decide to put in the effort to mow, pull out, or till under your cover crops, they're easy to deal with. What's more, they'll keep weeds in check and, if used in between rotated crops, they'll cut down on pests and diseases.
We're always here to enable your chill-out-on-the-porch time. Here's the stuff you need to make cocktail hour arrive that much sooner, and those veggie or mint garnishes taste all the better.
Which cover crops work best in the home garden?
We picked our favorite cover crop and green manure species based on ease-of-management, aesthetics, and utility. You can find most at your corner garden supply store, but if you're managing a larger area, you can buy them in bulk at feed and agriculture supply centers.
Annual ryegrass (Lolium multiflorum)
This is probably one of the more popular agricultural cover crops, but if it's used as a green manure, it leeches chemicals that may inhibit seed germination. Plan to use it where you'll set transplants, or sow hardier, large-seeded plants.
Annual ryegrass looks like clumping, deep green grass. Its deep roots excel at reducing soil erosion and compaction. This cover crop is suitable for no-till gardens, but you still have to cut the green stuff down and gently turn it into the soil with a hoe if you plan on following it up with a fall cool-season crop. Otherwise, let the first frost kill it.
- Use 12-15lb/acre if gently raked 1/4" to 1/2" deep, or 20lb/acre if you're broadcast seeding.
- Grows quickly in the cool season but holds its own in the heat.
- Absorbs excess nitrogen.
- It can overwinter in milder clients and is biennial in cooler regions, so if you overwinter it, be sure to kill it in its second spring before it goes to seed.
Crimson clover (Trifolium incarnatum)
Plant these spectacular legumes over large patches of fallow garden soil, or to keep weeds down in your home orchard. Blueberry growers in Northern states use them between rows as both cover crops and magnets for pollinators. In warmer regions, crimson clover is a popular choice for cool-season coverage. Wait until the flowers are just about to go to seed before turning it into the soil, and you can add between 70 to 150 pounds of nitrogen per acre.
- Crimson clover's leaves lack the pale chevrons found on other clover varieties.
- It does well in partial shade.
- Less-frequently called Italian or Scarlet clover, Crimson clover was imported from Italy in the 1800s.
- Inoculate the seeds with Rhizobium leguminosarum for ultimate nitrogen fixation, or buy pre-coated seeds.
- Broadcast over the soil surface or, if you're worried about birds, very lightly rake the seeds under the thinnest layer of topsoil. Don't plant deeper than a half-inch.
- Crimson clover grows 12" to 36" tall, so if you want to plant them among your vegetables (overseeding), they're best companions for corn and sunflowers.
Visit USDA's Sustainable Agriculture Research & Education (SARE) for more information on crimson clover.
Crimson clover is a showstopper, with deep red flowering spikes as long as an inch. The blooms attract pollinators in droves, but also predatory insects that take out thrips. If you're planning to graze livestock, it's far less likely than white clover to cause bloat.
Buckwheat (Fagopyrum esculentum)
Buckwheat matures in 70 to 90 days, though you'll want to cut and turn it into the soil before it sets seed. It's a tender annual, preferring spring and early fall weather. Buckwheat will tolerate midsummer heat if it's irrigated. Its tender nature also makes it quick to decompose in the soil, or you can mow or cut it for green bulk in your compost pile.
With cool, moist conditions, buckwheat can quickly reach 50". When it warms up, it may max out at 8" to 12", which may actually work in your favor if you're using it as a living mulch. Just be sure to water it if it begins to wilt.
- Buckwheat isn't a cereal grain. In fact, it's more closely related to rhubarb!
- Buckwheat will "soak up" excess soil phosphorus.
- As cool-season plants, buckwheat flowers give honeybees, butterflies, and other pollinators an enormous boost, bookending the main nectar flows.
- Buckwheat honey is as dark as Guinness stout with a molasses-like flavor. It's believed to be more nutritious than the average clover, or wildflower honey.
- Toast them to make kasha, or soak and cook them whole as part of your favorite hot cereal mix.
If you get lazy and let it go to seed, volunteers are extremely easy to pull by hand. Even better, turn your chickens loose, and they'll devour them, seeds and all. Plants die at first frost, so it's a fantastic end-of-season soil enhancer should you want to let it lay where it lands and cultivate it into the soil in early summer.
Hairy vetch (Vicia villosa)
Yeah, hairy vetch sounds like something your cat might leave on the rug, but this legume is actually quite gorgeous. It's related to Canadian milkvetch, which we carry as an ornamental, and there's no reason you shouldn't plant them together with the rest of your pretty stuff. It's also a good pasture plant if it's added to cereal grasses in smaller proportions. If "hairy vetch" gives you the willies, call it by its other common names: winter or fodder vetch.
Though it has shallow roots, it's often used to stabilize slopes, and its sprawling habit shades out weeds if planted densely enough. Give it some structure such as corn stalks or sunflowers, and it will climb like sweet peas. It has lavender flowers similar in shape to garden legumes, too.
- It prefers full sun, and while it will tolerate some drought, consistent irrigation will keep it perky.
- Hairy vetch is best raked into the soil at a depth of up to an inch, though it can be broadcast-seeded and gently tamped down in cultivated soil. Cover crop seeding rate is 20-25lb/acre.
- Like other tender cover crops, it grows best during the cooler season. It grows less densely after the summer solstice, after which time you might want to mix it with other varieties. Winter rye is ideal for spring, but oat grasses are better for fall.
- It matures in 30-45 days.
Table legumes and field peas
You can pick up field peas at most farm supply stores or garden centers that repackage large sacks into five-pound bags, or simply plan a very dense crop of your favorite garden peas, sweet peas, edamame, bush or pole beans. Note that agricultural-grade field peas and soybeans are usually pre-inoculated with the appropriate rhizobia, but you can easily find garden variety (pun intended) packets for your intended crop. Read the fine print, though: If you want the right stuff for your garden peas, beans, sweet peas, and vetch, Rhizobium Leguminosae and its subspecies are what you want; Sinorhizobium meliloti inoculates alfalfa. Planet Natural has a great page dedicated to garden inoculants and their uses.
Fodder for Thought
If you're planning to use cover crops as green manure, it can take a few weeks for the nutrients to break down into the soil. Still, your plants will benefit even if you fudge the timeline a bit. Decaying organic matter boosts the beneficial fungus in your soil, which in turn helps the roots access moisture and nutrients. As long as the turned green manure isn't cloddy, it will serve as a time-release nutrient source for your garden.
If you can get your hands on inoculants, they're easy to apply. The instructions will go into better detail, but usually, all you have to do is moisten the seeds or beans, shake them up with the right measure of inoculation, let them dry out, and plant them. Like little Sea Monkeys for the soil, water awakens the bacteria, which then colonize. It can live on in the soil for a few years after the host legume is long gone.
Oh...and we almost forgot. Don't fry your brain converting acres to square feet. Here's a converter for you!
Seed Needs Has You Covered!
We may not carry bulk cover crop seeds at the moment, but that's not the point: When your garden's healthy, we're happy. Contact us to find out if we can help you find the cover crop seeds you need, or if you'd be interested in having us add garden-size quantities to our online catalog.Do you have photos of any of these varieties in your garden? Connect with us on Facebook! We'd love to see what you're growing!