As fall arrives in full swing and the weather starts to get colder, it is inevitable (for almost all of the growing zones) that the gardening season comes to a close for winter. In my garden, this means it’s time to plant cover crops.
For a long time, the generally accepted garden practices were to pull all of your plants out by the roots in the fall and till in the spring. In between the end of one growing season and the beginning of next, gardeners left the ground bare.
We have since learned that bare soil in the winter allows for wind and water erosion. Bare soil in nature means death; the ground is never bare in a healthy ecosystem. Annual plants fill in open spots until perennial plants fill in and everything remains over the winter, maintaining soil health and feeding soil life in effect. We usually disrupt this natural cycle in our gardens, but it doesn’t have to be this way.
Cover Crops: What are They?
Gardeners can practice regeneration in their gardens by growing cover crops. Cover crops are grasses and legumes that are grown during the off-season to enrich and protect the soil while also sequestering carbon. The seeds are generally sown in the fall once the garden is cleared and they are left until spring. When the time to garden comes around in spring, the cover crop is mowed and the roots are left to decompose, further enriching the soil. Cover crops feed soil microbes, prevent erosion, loosen and aerate compact soil and create a more nutrient-rich environment for your summer crops.
Deciding Which Cover Crop(s) to Grow
The main factor I suggest one considers when choosing cover crops is the timing. Some crops “winter kill,” or die permanently in freezing temperatures. Others can survive the cold and will remain in the springtime. These types of cover crops must be terminated manually through a variety of methods. Plants that winter kill are easier; however, they have to be planted with plenty of time to establish roots before the first frost of the year. If you have more mild winters, a long growing season, or you are willing to put your beds to rest early, these can be a good option for you. On the other hand, if you get a late start, have an early first frost or want to have as long of a growing season as you can, choose a cover crop that does not winter kill.
If you have garden beds with large plants that are off the ground, such as trellised tomatoes, cucumbers, eggplants or peppers, you can “undercrop” by planting the cover crop into the soil around the plants. This allows you to plant early and the cover crop will have plenty of time to grow. By the time it’s tall enough to interfere with your vegetable plants, the season should be coming to a close and the summer plants can be removed. This is challenging if you have garden beds of root vegetables, greens or other crops that cover the ground, but it is a great option to keep in mind if it applies to your garden.
As with any gardening, biodiversity is always best. The general recommendation is to grow 3-8 different cover crops at the same time by making or buying a mix. This can sometimes be too challenging or too expensive, so don’t let that stand in your way of growing a cover crop. If you can only manage to plant one type, that is far better than nothing!
When to Plant
This varies so much based on where you live and which cover crop you are growing. I am growing winter rye because I am able to start it much later and I have a relatively early first frost. I planted the winter rye after the first frost and it will grow throughout the winter. Each plant has a germination temperature (the lowest temperature at which a seed will germinate) and a kill temperature (the lowest temperature at which the plant can survive once established). It is always helpful to research the cover crop(s) you chose a little bit to make a plan of action.
Common Cover Crops:
Preparing the Soil
To remove dead or spent plants, simply cut the main stem right above the surface of the soil. Doing this instead of pulling it up by the roots eliminates soil disturbance and leaves organic matter (the dead roots) in the soil to feed the microbes and decomposers over the winter.
Once the plants are cleared, use a three-tined fork or a broadfork to loosen and aerate the soil. I do this with a fork every 3-6 inches, depending on how compact the soil is. Avoid turning any soil and focus on minimal disruption. The idea is to get air down into the soil and loosen everything up while maintaining the soil structure.
After that, you can decide whether you would like to top dress in the fall or spring. Top dressing is simply layering compost onto the top of your soil at a thickness of 1-3 inches. It does not matter when, but top-dressing in the fall does allow the compost time to be worked down into the soil during the winter months. With my bigger garden beds, I wait until the spring. I am tired and busy in the autumn months and prefer to keep my to-do list short. In the spring, I’m anxious to get out in the garden and would gladly welcome another task. Ultimately, it is up to you; just make sure you top dress at least once a year.
Once you have top dressed your garden or decided to wait, you can get to planting.
Planting your Cover Crops
Cover cropping is the easiest seed planting because you don’t have to follow the instructions for spacing or even depth. These are not meant to be healthy, thriving plants that produce a lot of fruit. They are merely meant to grow good roots and cover the soil.
To plant cover crops, I simply broadcast plant the seeds and rake them into the soil. I try to get as many of them covered as I can, but again, this is not about precision. Once the seeds are raked in, give them a good soaking of water and continue watering daily until the seeds have germinated and the plants are established. As the plants begin to grow, I will taper off watering and then let them be over the winter.
What to Do in the Spring
Now that you have a thick layer of unwanted plants growing in your garden, the question is how to remove them?
Most of the cover crops won’t be an issue because they winter-kill. If you grew winter rye, this likely did not happen. You will have to “terminate” your cover crop, or figure out a way to kill it so it doesn’t steal resources from your garden crops. For many cover crops, simply cut it back with a weed whacker, clippers or a scythe. This should be done right when it is getting ready to bloom or earlier if you need to get started with spring planting. The plant will die and the roots will decompose, adding nutrients and organic matter to your soil. The decomposing of the roots is what fixes the nitrogen in your soil, so it’s very important to avoid pulling the plants out!
Alternatives to Cover Crops
If you ran out of time to plant cover crops, don’t have the extra money to spare (for the record, the seeds are very inexpensive!) or just can’t pull it off this year, I get it. That does not mean you have to leave your soil bare all winter. Prep the soil the same way you would if you were planting, they cover with a heavy layer of dried leaves or other mulch (cut grass or seed-free straw, for example). Give it a spray of water to mat it down a bit so they don’t blow away and call it good. The leaves will break down into the soil and enrich it.
Mulching with leaves is a great option, too, because leaves provide an important habitat for many insects over the winter! I like to leave my flowerbed as it is with dead plants to provide seeds for birds and other critters during the winter and mulch with leaves for the insects. It’s an incredibly easy way to help wildlife with your garden!
Cover crops may seem like a lot of extra effort at first, but they truly help your soil health so much and they are worth the investment. Happy planting and as always, feel free to reach out if you have questions!
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