Cover Crops in the Vegetable Garden
Soil structure, fertility and covering the soil are some often over looked aspects of the vegetable garden that can play a big role in the success of your gardening season. You might be wondering why should we care about the soil structure and soil cover? Why is it important? Soil structure impacts how well the plants grow as it impacts how water moves into or through the soil along with how much oxygen is available for your vegetables to use. If the soil is uncovered you are likely to have weeds that take advantage of that open ground to grow. One way that we can improve the soil in your vegetable garden is by utilizing cover crops through late summer and into the fall or winter.
So why should we spend the time and energy to plant another crop in your garden? In a short answer, cover crops planted in fall are an inexpensive way to build better soil for your spring garden and improve your soil fertility. Cover crops serve as a living mulch cover the soil and preventing weeds from germinating in the garden. They consist of grains, grasses, brassicas, or legumes that will grow during fall and winter and that you can mow, spade, or till under in the spring. During their growth, cover crops help reduce soil compaction, capture excess nutrients, and prevent erosion. Their roots penetrate and help loosen heavy-textured soils, allowing better air and water penetration. Legume cover crops add nitrogen to the soil. When you turn cover crops under, they add organic matter, building better soil structure and fertility or you can cut them off and use them as a mulch to keep the soil covered for the growing season.
There are a three different types of cover crop plants that can be planted. The first are the legume or pea family. These plants help to facilitate the fixing of nitrogen in conjunction with some soil borne bacteria through nodules in the legumes roots. When these roots break down the nitrogen is released into the soil to be used by plants the next growing season. Some examples of this family include clovers, field pea, hairy vetch and sun hemp. The second group include the non-legume broadleaves. These group is the most diverse and are used to help add nutrients to the soil or in the case of radish to improve soil structure. Some examples of these plants include radish, turnips, kale, mustards and canola. Be sure to keep these from going to seed to prevent them from becoming a weedy mess. The final group of cover crops is the grass group. These cover crops are the best for building organic material and cover for the soil because of their abundant root system and the amount of leaf growth above the ground. They include annual or winter rye, wheat or oats.
How do you get started? One of the easiest ways to get started with cover crops is to scatter leftover cool season crop seeds such as radish, kale and carrots in a section of the garden. If this is your first season I recommend using plants that will winter kill in our area for the first year trying. If possible, over time, move to a mix of cover crops that includes legumes, grasses and other broadleaves depending on your goals and how much money you want to spend on your garden. Most of our cover crops should be planted by mid-October but some plants such as winter rye, wheat, or kale will continue to grow till the soil freezes in the fall. Ultimately what species you use will depend on what your goals are. If you have compacted soil consider using turnips or radishes to help improve the soil structure, if you have weed issues consider using winter rye to suppress weeds. Cover crops are a useful tool in the toolbox to help improve your soil. Depending on your needs you can make your mix as simple or complicated as you want. I will say the more diverse the mix, usually the better. For more information check out this publication: https://www.extension.purdue.edu/extmedia/HO/HO-324-W.pdf
