One of the major recent movements in production agriculture has been the widespread adoption of cover crops. This practice gives farmers a host of benefits, from erosion prevention to nutrient retention and recycling. However, using cover crops isn’t just for large scale farming operations. Hobby vegetable gardeners can absolutely employ similar systems on a smaller scale to reap the same benefits. For the past two years, I’ve used Buckwheat to provide a soil building cover during the heat of summer between spring and fall gardens. This winter, after my fall greens garden succumbed to frost, I decided to employ the same tactic with a mix of Red Clover (Trifolium pratense), White Clover (Trifolium Repens), and Crimson Clover (Trifolium incarnatum) to enhance my soil during the coldest months until spring tomato planting arrives!
Clover mix used as a cool season cover crop in raised beds. Photo courtesy Daniel Leonard.
While there are many different species of plants (rye, oats, wheat, various brassicas, etc.) that can be planted in November or December as cool season covers to deliver benefits like winter weed suppression, enhance soil organic matter, retain and harvest leftover nutrients, and provide habitat for beneficial insects, I chose Clover for an additional reason. In addition to the above benefits, Clover is a legume and also fixes atmospheric nitrogen, making it available for subsequent plantings! Not only is Clover an excellent soil cover, but it also provides some nitrogen fertilizer to the following vegetable garden!
Growing Clover, while not quite as simple as Buckwheat or small grain covers like oats and rye, is relatively easy for most gardeners. The first step is selecting which clover species and/or variety to grow. I chose a mix of Crimson, White, and Red Clover simply because I had several pounds of each left over from a previous field planting. However, any one of the three may be used by themselves or in various combinations. All are excellent choices for garden cover crops and have similar growing requirements. Crimson Clover is the most readily available, but all three species can be found at most farm and garden supply stores.
The next step is to prep your garden beds for clover seeding. I thoroughly remove weeds from my raised beds, lightly till the top couple of inches of soil, and rake to provide a level surface. Since clover seed is tiny, a smooth, clean seedbed is a must for excellent germination. Once this is done, your next should determine how much seed to plant. Recommended clover seeding rates are usually given on a per acre basis and range from 3-4 lbs/acre (White Clover) to 20-25 lbs/acre (Crimson Clover). Given these seeding rates, planting in a 4’x8’ (32 ft2) raised bed is only going to require a miniscule amount of seed.
Clover mix used as a cool season cover crop in raised beds. Photo courtesy of Daniel Leonard.
To ensure a good stand while minimizing risk of overplanting, I mix equal parts clover seed and either sand, vermiculite, or other media similar in size to clover seed and hand scatter over the surface of my beds, making sure to uniformly cover the entire bed. If you think the stand is too thick, you can always hand-thin after emergence.
As a group, clovers prefer moist soil that is not allowed to dry out completely. This isn’t usually a problem given the Panhandle’s frequent rainy cold fronts in winter, but if rainfall is inconsistent, some irrigation will be required. Supplemental fertilizer isn’t normally necessary when planting a clover cover in vegetable gardens because nutrients remaining from the previous veggie crops are usually sufficient for growth and development (N especially is not needed as legumes produce their own through N fixation). 2-3 weeks before you’re ready to plant your spring veggies, chop the clover cover into the top few inches of your bed to terminate it and release its nutrients back into the garden. It’s that easy!
Planting a winter legume cover crop like clover is a great way to harness the benefits of cover crops for your spring veggies and enhance the aesthetics of your otherwise barren and drab garden beds! For more information about growing winter cover crops or any other horticultural topic, contact your local UF/IFAS County Extension office. Happy Gardening!
Daniel Leonard, Horticulture Agent at UF/IFAS Extension Calhoun County, answers commonly asked questions about raised bed gardening. In the video he discusses construction materials, the type of soil to use, fertilization, crop rotation, cover crops, and smaller container gardens.
2020 has not been the most pleasant year in many ways. However, one positive experience I’ve had in my raised bed vegetable garden has been the use of a cover crop, Buckwheat (Fagopyrum esculentum)! Use of cover crops, a catch-all term for many species of plants used to “cover” field soil during fallow periods, became popular in agriculture over the last century as a method to protect and build soil in response to the massive wind erosion and cropland degradation event of the 1930s, the Dust Bowl. While wind erosion isn’t a big issue in raised bed gardens, cover crops, like Buckwheat, offer many other services to gardeners:
Buckwheat in flower behind summer squash. Photo courtesy of Daniel Leonard.
Covers, like Buckwheat, provide valuable weed control by shading out the competition. Even after termination (the cutting down or otherwise killing of the cover crop plants and letting them decompose back into the soil as a mulch), Buckwheat continues to keep weeds away, like pinestraw in your landscape.
Cover crops also build soil. This summer, I noticed that my raised beds didn’t “sink” as much as normal. In fact, I actually gained a little nutrient-rich organic matter! By having the Buckwheat shade the soil and then compost back into it, I mostly avoided the phenomena that causes soils high in organic matter, particularly ones exposed to the sun, to disappear over time due to breakdown by microorganisms.
Many cover crops are awesome attractors of pollinators and beneficial insects. At any given time while my Buckwheat cover was flowering, I could spot several wasp species, various bees, flies, moths, true bugs, and even a butterfly or two hovering around the tiny white flowers sipping nectar.
Covers are a lot prettier than bare soil and weeds! Where I would normally just have either exposed black compost or a healthy weed population to gaze upon, Buckwheat provided a quick bright green color blast that then became covered with non-stop white flowers. I’ll take that over bare soil any day.
Buckwheat cover before termination (left) and after (right) interplanted with Eggplant. Photo courtesy Daniel Leonard, UF/IFAS Calhoun County Extension.
Now that I’ve convinced you of Buckwheat’s raised bed cover crop merits, let’s talk technical and learn how and when to grow it. Buckwheat seed is easily found and can be bought in nearly any quantity. I bought a one-pound bag online from Johnny’s Selected Seeds for my raised beds, but you can also purchase larger sizes up to 50 lb bags if you have a large area to cover. Buckwheat seed germinates quickly as soon as nights are warmer than 50 degrees F and can be cropped continuously until frost strikes in the fall. A general seeding rate of 2 or 3 lbs/1000 square feet (enough to cover about thirty 4’x8’ raised beds, it goes a long way!) will generate a thick cover. Simply extrapolate this out to 50-80 lbs/acre for larger garden sites. I scattered seeds over the top of my beds at the above rate and covered lightly with garden soil and obtained good results. Unlike other cover crops (I’m looking at you Crimson Clover) Buckwheat is very tolerant of imperfect planting depths. If you plant a little deep, it will generally still come up. A bonus, no additional fertilizer is required to grow a Buckwheat cover in the garden, the leftover nutrients from the previous vegetable crop will normally be sufficient!
Buckwheat “mulch” after termination. Photo courtesy of Daniel Leonard, UF/IFAS Calhoun County Extension.
Past the usual cover crop benefits, the thing that makes Buckwheat stand out among its peers as a garden cover is its extremely rapid growth and short life span. From seed sowing to termination, a Buckwheat cover is only in the garden for 4-8 weeks, depending on what you want to use it for. After four weeks, you’ll have a quick, thick cover and subsequent mulch once terminated. After eight weeks or so, you’ll realize the plant’s full flowering and beneficial/pollinator insect attracting potential. This lends great flexibility as to when it can be planted. Have your winter greens quit on you but you’re not quite ready to set out tomatoes? Plant a quick Buckwheat cover! Yellow squash wilting in the heat of summer but it’s not quite time yet for the fall garden? Plant a Buckwheat cover and tend it the rest of the summer! Followed spacing guidelines and only planted three Eggplant transplants in a 4’x8’ raised bed and have lots of open space for weeds to grow until the Eggplant fills in? Plant a Buckwheat cover and terminate before it begins to compete with the Eggplant!
If a soil building, weed suppressing, beneficial insect attracting, gorgeous cover crop for those fallow garden spots sounds like something you might like, plant a little Buckwheat! For more information on Buckwheat, cover crops, or any other gardening topic, contact your local UF/IFAS County Extension Office. Happy Gardening!
