Fall is one of the busiest times of the year for gardeners. It’s time to finish the harvest, store your garden supplies and put your garden to bed for the winter. This fall, consider planting a cover crop — sometimes called green manure — to the list as well.
Winter cover crops have been used mainly by farmers to protect and nourish their fields. However, in recent years, backyard gardeners are realizing the value of cover crops and the benefit of them for their gardens. While the gardener is taking a much-deserved break while planning for the next year’s garden, the cover crop can be hard at work improving the soil, adding nutrients and getting the ground ready for the spring.
Cover crops can be used in any garden, including raised bed gardens. The cover crop seeds are usually fast germinating and fast growing. The purpose of a cover crop is to literally cover the garden with a living blanket of plant matter to sustain soil life. Here are some of the benefits of a cover crop:
There are many different cover crops to choose from and each will offer different benefits. Some will grow better in your grow zone than others. You may have to experiment a little to decide which ground cover is best for your situation. There is no reason that you can’t divide the garden up or plant each raised bed with a different cover crop so you can experiment which will work best for your garden.
For the home gardener, an annual cover crop is preferred over a perennial. The annual will either complete its growth cycle by spring or it will die in the cold temperatures of winter. Perennial cover crops are more difficult to dig under in the spring and can be a problem to eradicate from the garden.
Cover plants should be planted in late summer or early fall in the north. In the south, you can plant as soon as you finish harvesting. Cover crops need at least four weeks to get established before the first frost. If you live in the north where the first frost can come early in the fall, consider planting the cover crop immediately after harvesting a section of the garden or you could seed the cover crop between the remaining crops.
The four most common cover crops are Red Clover, Hairy Vetch, Winter Rye and Oats. The choice should be determined by the grow zone you live in and the primary reason you are planting the cover crop, including:
Till or loosen the top few inches of the soil and then lightly rake to give a good planting surface. Simply hand scatter the seeds over the area and rake in if the seeds are small. If the seeds are large, plant in rows that are close together. Cover with soil equal in depth as the size of the seeds and then tamp down gently with the back of the rake. Lightly water and cover with a thin layer of straw to protect the bed from heavy rain and wind while the seeds germinate.
If you are planting legumes, you will want to use inoculant to guarantee the nitrogen fixing process. The inoculant is a bacteria called Rhizobium leguminosarum that causes the beans or peas to form the nodules and store the nitrogen. Without these bacteria, the plants may not have the nitrogen they need to grow as well as replenish the nitrogen in the soil.
There are two ways to apply the inoculant. It can be added right to the soil as you plant the seeds, or you can apply it to the seeds directly. Simply pour the seeds into a water-filled dish to wet them and then roll them in the inoculant. Some gardeners add one part corn syrup to 10 parts hot water to the inoculant. Let it cool before using and then add the seeds, as this helps the inoculant to stick to the seeds.
Besides the rake and seeds, the inoculant is one of the only indoor garden supplies you will need to grow a cover crop.
When early spring arrives and your perennial cover crops resume growing, many will want to flower and then set seed. The danger is that your cover crop could become a weed-like plant. The annuals will be dead from the cold, with some lying on top of the ground and others still standing. You now have three options: use the plant matter as a mulch, add the plant matter to the compost bin or dig the plant matter into the soil.
Regardless of which you choose, it is best to cut the organic matter into smaller pieces so it can be utilized in the soil sooner. Depending on what type of cover crop you planted, you can chop it up with garden shears, a string trimmer or you can even use a mulching mower. If your cover crop is a nitrogen fixer, don’t pull the roots out of the ground. Once you have chopped the plant material, remove it to the compost bin. You can also leave it on the surface of the soil and simply move it over when the time comes to allow planting.
If you want to improve the soil with the organic matter, either work it into the soil with a garden fork or use a rototiller. You should wait two to three weeks before you plant so the breakdown of the material can proceed and the benefits of the organic matter you added — as well as the nitrogen fixing — can set in.
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These are some cover crops you may want to consider trying in your garden:
Hardy Legumes — These cover crops will add organic matter to your soil, and they will increase the nitrogen. You should be sure to mow these down before they flower in the spring. Some hardy legume options for you to consider include:
Tropical Legumes — These legumes need warm weather to grow. They can be planted as a cover crop in the southeast and southwest parts of the country. They will produce a large amount of organic matter and increase the level of nitrogen in the soil. Northern gardeners will need to plant this as a summer annual. Some tropical legume options for you to consider include:
Grasses — Grasses don’t add nitrogen to the soil, but they do help if you have compacted soil and they tolerate cold temperatures.
Grasses are great for controlling erosion, but these are annuals so cut them down before they set seed and/or till them under. Some grass options for you to consider include:
Other Annual Cover Crops — These cover crops will produce a lot of organic matter, but they will not increase the nitrogen levels. Some other cover crop options for you to consider include:
Start Seeds Early with Indoor Gardening Supplies
Let this be the year that you use a cover crop to protect your garden soil and improve its condition. Decide which one will meet your priorities or even try a mix of different cover crops in the same area. The benefits could be a game changer in your garden.
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