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With the end of the warm-weather gardening season here, many of us relax and forget to take what may be the most important step to maintain the fertility of our vegetable and fruit sites — planting a cover crop.
You may be wondering why planting another crop on the same site as our food crop would be beneficial. Wouldn't it be better to let the soil rest through the winter? Isn't this new crop going to further deplete the soil? The answer to these questions is a resounding “no”. Let me explain.
When the summer vegetable growing season ends, we usually clean up our garden by pulling out the remaining plants and composting them. That leaves the soil bare and open to the elements all winter, potentially causing compaction from rain, erosion from water runoff, and leaching of nutrients into the water table. By spreading a little compost on the garden and then planting a cover crop, you can protect the soil. September and October are the best months for planting winter cover crops because the soil is still warm for seed germination and the fall rains will help give it a good start.
What plants should you use as cover crops? Many good plant selections have been tested at Oregon State University over the years. The most widely used plants are annual grasses that won't become weedy, and legumes. These are plants that help fix nitrogen in the soil. The best grasses are annual ryegrass, barley, oats, wheat, or triticale. The most common legumes used are fava bean, Austrian winter pea, crimson clover, and hairy vetch. The seeds or mixes can be purchased at the local farm stores or from local seed producers. I recommend using a mix of one grass and one legume, such as annual rye and hairy vetch. For a 1,000-square-foot-garden site you will need about 2 pounds of annual rye seed and about 1 pound of vetch seed. The legume seed should always be treated with a bacterial inoculant to help it fix more nitrogen in the soil. Just mix the grass seed and the legume seed together before spreading it on your garden.
Grasses and legumes each provide special services for the soil. The annual grasses have fibrous root systems that forage widely, capturing available nutrients that would otherwise leach out of the root zone. Grasses grow vigorously during the fall and into spring to make a large amount of plant material to be turned under in spring. All this material feeds the biotic life in your soil, which leads to improved soil structure and fertility. The legume fixes nitrogen in your soil and grows low to the ground providing an excellent cover against rainfall compaction. Having a cover crop on your soil during winter also prevents your site from being over run by pesky weeds.
In the springtime, about 30 days before you want to plant your vegetable garden, you should mow down and till the cover crop into the soil. You will be well on your way to a better garden.
Steve Renquist is the Horticulture Extension agent for OSU Extension Service of Douglas County. He can be reached by e-mail at steve.renquist@oregonstate.edu or by phone at 541-672-4461.
You may be wondering why planting another crop on the same site as our food crop would be beneficial. Wouldn't it be better to let the soil rest through the winter? Isn't this new crop going to further deplete the soil? The answer to these questions is a resounding “no”. Let me explain.
When the summer vegetable growing season ends, we usually clean up our garden by pulling out the remaining plants and composting them. That leaves the soil bare and open to the elements all winter, potentially causing compaction from rain, erosion from water runoff, and leaching of nutrients into the water table. By spreading a little compost on the garden and then planting a cover crop, you can protect the soil. September and October are the best months for planting winter cover crops because the soil is still warm for seed germination and the fall rains will help give it a good start.
What plants should you use as cover crops? Many good plant selections have been tested at Oregon State University over the years. The most widely used plants are annual grasses that won't become weedy, and legumes. These are plants that help fix nitrogen in the soil. The best grasses are annual ryegrass, barley, oats, wheat, or triticale. The most common legumes used are fava bean, Austrian winter pea, crimson clover, and hairy vetch. The seeds or mixes can be purchased at the local farm stores or from local seed producers. I recommend using a mix of one grass and one legume, such as annual rye and hairy vetch. For a 1,000-square-foot-garden site you will need about 2 pounds of annual rye seed and about 1 pound of vetch seed. The legume seed should always be treated with a bacterial inoculant to help it fix more nitrogen in the soil. Just mix the grass seed and the legume seed together before spreading it on your garden.
Grasses and legumes each provide special services for the soil. The annual grasses have fibrous root systems that forage widely, capturing available nutrients that would otherwise leach out of the root zone. Grasses grow vigorously during the fall and into spring to make a large amount of plant material to be turned under in spring. All this material feeds the biotic life in your soil, which leads to improved soil structure and fertility. The legume fixes nitrogen in your soil and grows low to the ground providing an excellent cover against rainfall compaction. Having a cover crop on your soil during winter also prevents your site from being over run by pesky weeds.
In the springtime, about 30 days before you want to plant your vegetable garden, you should mow down and till the cover crop into the soil. You will be well on your way to a better garden.
Steve Renquist is the Horticulture Extension agent for OSU Extension Service of Douglas County. He can be reached by e-mail at steve.renquist@oregonstate.edu or by phone at 541-672-4461.
