Now’s the time to plant winter cover crops to prepare the soil for next year’s vegetable garden – Oregon State University | Directory Mayhem

CORVALLIS, Ore. – Nobody wants to think about the end of the harvest when the vegetable garden is at its peak, but now is the time to plant overwintering crops to improve your soil for the next season.

If you’re unfamiliar with cover crops, here’s the synopsis: These hardworking plants can add organic matter and aerate soil, protect it from compaction from rain, suppress weeds, and reduce erosion, according to Nick Andrews, organic vegetable specialist for Oregon State University Extension Service. As a bonus, if you let them flower, their flowers will provide nectar and pollen for pollinators and other beneficial insects.

Not a bad deal for a nearly maintenance-free system. To get off to a good start, prepare your soil and distribute seed liberally, raking in lightly and watering as needed until the fall rains begin. Enjoy watching your cover crops grow in the winter before incorporating them in the spring.

Cover crops include grains such as winter oats, grain rye and a wide range of deciduous plants. Legumes, such as the commonly used purple clover, Austrian field pea and common vetch, are nitrogen “fixers”. Beneficial bacteria in legume root nodules absorb nitrogen from the air and transport it to the plant. When the cover crop rots in spring, some of that nitrogen becomes available to fertilize next year’s vegetables. When cost is an issue, legume cover crop nitrogen is much cheaper than organic nitrogen fertilizer and competes with traditional fertilizer prices.

Timing is key for catch crops, Andrews said. Plant seeds from overwintering cover crops by September or early October, before the weather becomes too cold and wet for them to germinate and become established.

When planting, make sure that the seed is in good contact with the soil. Larger seeds such as peas, vetches and corn should be raked in lightly. Mix small seeds with sand to make them easier to disperse, then pour in with a sprinkler. If the weather is still dry, water the area. For veggies you harvest after early October, consider sowing into your established crops in the summer before they cast too much shade for sun-loving veggies.

Be prepared to manage your cover crop in spring and kill it before it sets seed (unless you want some of the seed, faba beans for example). In our climate, most gardeners use catch crop residues to encourage decomposition. Do this three to four weeks before planting vegetables so the crop will decompose well. Otherwise, it may promote some diseases and attract some insect pests.

If you don’t have three to four weeks for the cover crop to decompose, you can remove the stems and leaves and apply them elsewhere as mulch or compost, or dig the cover crop deeper into the soil. When you need to kill the crop depends on when you need to plant your veggies.

“Big is better when it comes to cover crops,” Anderson said. “If you can, let the plants grow to early flowering. Just be prepared to incorporate big harvests when you grow them. You will see why organic farmers love cover crops.”

When it comes time to kill the cover crop, pick shorter plants straight into the ground. If the plant is too tall to easily turn under, mow first or use a weed trimmer. Hard stemmed plants can be cut and rotted above ground. Or you can place the tops on the compost heap and bury the roots. Some experienced gardeners who don’t want to till their soil get good results with tarps, Andrews said. Regardless of the method, let the upturned material sit until it’s time to plant.

For beginners, Andrews advises:

  • Start with a cover crop that is easy to grow and manage. Purple clover and phacelia, for example, are relatively easy to incorporate into the soil.

  • Prepare your garden for cover crops and have sprinklers on hand for when the weather is dry. It’s a good idea to water the soil a little before preparing the seedbed if the soil is very dry.

  • When trying cover crops for the first time, plant them in an area of ​​your garden that you can leave for vegetables, which are usually planted in May or June. This gives you time to learn how to deal with catch crop residues in spring.

  • After you’ve successfully used one cover crop, try another in a different area of ​​your garden. Then, as you gain experience, experiment with blending, bedding, sheeting, and other innovative practices.

For more information, see Cover crops for home gardeners East of the Cascades and West of the Cascades; and Methods for Successful Cover Crop Management for Gardeners, all Washington State University publications on which Andrews contributed.

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