A lush garden full of healthy plants begins with great soil. That's why after one growing season ends, it’s important to replenish your soil so that it can grow healthy crops for you next year, too. One of the best ways to do this is by planting cover crops in it. Also referred to as “green manure,” cover crops revitalize the soil, suppress weeds, and help control harmful pests and diseases. Cover crops include legumes and grasses, which grow quickly and pump nutrients back into the soil.
Planting Cover Crops in Healthy Soil
Once you’ve harvested everything you’ve grown and pulled your annual crops, you can plant cover crops to prevent weeds from taking over your bare garden plot, no matter its size. Typically, seeds for cover crops are planted a few weeks before the hard frosts begin. If you live in an area that gets any snow (i.e. zones 5 and above), you can use cover crops to protect the soil during the winter, making it easier for you to mulch in the spring.
The benefits of cover crops are many. Not only do they increase the fertility of and amount of organic matter in your soil, but they also improve airflow and prevent erosion and soil compaction. Plus, they attract beneficial insects both above and below the soil into your garden, including bees and earthworms. Cover crops can stop the spread of soil-borne diseases and play an important role in nutrient cycling. Think of them as beneficial placeholders for the plants you intend to grow later on.
When to Plant Cover Crops
The best time to plant your cover crops is a few weeks before the first hard frost. This will give them enough time to establish themselves before cold, inclement weather arrives. Planting is easy: rake the topsoil and spread the seed over it. Then, rake it into the soil and wait for the plants to grow. Keep the ground well-watered, especially if you live in an area that experiences drought-like conditions.
If you don’t plant cover crops in a particular section of your garden because you'd like to keep it bare or are planning on cultivating something else there later in the year, you'll probably need to mow that section at least semi-regularly. This will prevent the cover crops from competing with any flowers and vegetables that might be growing there.
Since cover crops act as placeholders for other plants in the garden, there will eventually come a time when you’ll need to kill them off so you can plant the varieties you want in their place. The best time to do so is when they begin to flower and set seed.
The best way to kill these plants is to use a mower or weed trimmer to hack them down at the base close to the soil. Once the stems and leaves have dried, dig them into the soil. You won’t be able to plant in the area right away — we suggest waiting a few weeks to a month to give the dead plants time to decompose. However, don’t wait too long to plant, or you could lose a lot of the benefits the cover crops offered you in the first place.
Cover Crops to Grow
If you’re thinking of growing cover crops, you have a lot of options to choose from. Crops like clover, alfalfa, and legumes are all nitrogen-fixing all-stars, which take nitrogen from the air and return it to the soil. Clover also attracts beneficial insects to the garden.
Buckwheat is another cover crop that’s fast growing and very easy to cultivate. It’s cold-tolerant, attracts beneficial insects, and is ideal for replenishing nutrients in depleted soil. Buckwheat plants can grow up to nearly two feet in a single month if conditions are right. When you’re ready to plant next year's crops, pull the buckwheat up or cut it at the soil line. The dried plants can be used to make great mulch for the garden, or you can just dig them into the soil.
Winter rye is a crop that returns biomass into the soil and has the additional benefit of being very hardy. Plant it in the late summer or early fall (now is the best time) to give the rye enough time to establish its roots and grow a little before the cold weather hits. In the spring, chop it at the base of the stem and work the rest of the plant into the soil. You may have an excess of plant matter. If that’s the case, just add it to your compost bin.
Barley is another fast-growing plant, and it's great at capturing nitrogen in the soil that may have been left over from the crops you planted earlier in the year. Plant it in the late summer to reap the maximum benefit. If you're into brewing, this plant offers an added bonus: use the harvest in your next batch of beer!
If legumes are your thing, check out hairy vetch. These plants are hardy to zone 4 and are best planted in early fall. As a legume, hairy vetch naturally returns nitrogen into the soil. When you’re ready to plant next year's garden, cut it below the crown and let the rest of the plant dry out.
In a lot of cases, cover crops that are planted together can work together to rebuild soil. Take oats and winter peas for example, which when planted in the early fall help return nutrients into the soil. Still, be sure to remove them from the garden before the end of April by mowing them and then pulling or hoeing the remaining vegetation. The longer cover crops sit in the ground, the more difficult they are to remove.
Give your garden the best start in the spring by taking steps to replenish its soil in the fall. A bit of work now is sure to pay off when you can freely work the soil again come next growing season.