By Bonnie Kirn Donahue, UVM Ext. Master Gardener
Rather than leaving a field or patch of soil open over the winter, consider cover crops. A cover crop is basically a temporary seeding of an area that would otherwise have exposed soil. The crop is a placeholder for future crops that will be grown there. There are lots of reasons to use cover crops. First, soil is stabilized during transition times, preventing erosion and soil movement that may occur when not vegetated.
Second, vegetating exposed areas prevents rain and stormwater runoff from depositing soil particles and nutrients into nearby rivers and streams. The cover crops help to absorb and capture water, and help hold nutrients in the soil.
Third, cover crops are typically meant to be annual or one-season crops. Once the crop is no longer needed, it can be tilled back into the soil, which will provide organic matter and nutrients to the soil as it decays.
There are many species that can be used as cover crops. Keep in mind, the purpose of the cover crop, the timing of planting and what your soil needs.
Cover crops also can be used when planting seed mixes with slower-growing seed species. Native, pollinator seed mixes often need a cover crop, which will provide quick establishment and erosion control while the native species become established.
If you are seeding an area in the spring, using oats (Avena sativa) works well as it grows quickly in warm weather, and it will be killed by frost in the fall. For planting in late summer or fall, winter or cereal rye (Secale cereale) is recommended because it grows well in cold conditions.
Annual rye (Lolium perenne ssp. mulitflorum) is often already included in seed mixes for lawns. It establishes quickly and creates great (temporary) cover while the other grass seeds are getting established.
Be careful though as planting too much annual rye or letting it grow too tall can smother the seed that you actually want to grow. Make sure to follow the manufacturer’s seed rate recommendations, and mow the grass when it grows taller than eight inches.
For areas where you just need temporary cover, you could use one of the grass or grain species listed above, or you could plant other species that have other useful features.
Hairy vetch (Vicia villosa), red clover (Trifolium pratense) and winter peas (Pisum sativum) are species that fix nitrogen, boosting soil health. Both species flower profusely, so they offer food for pollinators while planted.
Alfalfa (Medicago sativa) and buckwheat (Fagopyrum esculentum) are also great multipurpose cover crops that produce flowers that attract pollinators, establish quickly and suppress weeds.
If you have compacted soils, consider using a brassica cover crop such as tillage radish. Its hearty taproots will break up the soil and improve soil aeration.
To determine the quantity of seed needed, you will need to know the size of the area you want covered. Then, look for the seed rate on seed manufacturers’ bags or websites to calculate how much seed you need. You might need to do some conversions, so keep a calculator handy.
Cover crops are an excellent way to give back to the soil and environment around us. Give it a try this season and see how you feel about it!
