A cover crop is a quick growing crop that is planted primarily to keep the soil covered for a short period of time, then plowed under as “green manure” or composted.
Most gardeners know about the benefits of adding organic matter to the soil. Many of us build the soil with annual applications of compost, manure, leaves, and grass clippings. Cover crops allow you to avoid importing soil amendments. By growing your own organic matter, you eliminate the fossil fuels needed to transport imported amendments, helping to make your yard a closed loop of energy inputs. (Ref: Edible Landscaping with Charlie Nardozzi: Fall Garden Cover Crops)
With cover crops, large amounts of organic matter are added to the soil when the lush growth of green, mature crops is turned under. Organic matter improves soil texture as humus and stabilizes moisture content. The plant nutrients in these crops are returned to the soil, thus becoming a storehouse for nutrients.
Cover crops can provide a wonderful habitat for the pollinators that help keep your garden thriving. Flowering Cover crops such as crimson clover, buckwheat, alfalfa and mustard attract bees and beneficial insects that help with pollination and insect control in the garden. Cover crops encourage beneficial insects by providing flowers for a nectar source and foliage for shelter.
Large amounts of organic matter are added to the soil when the lush growth of green, mature crops is turned under. Organic matter improves soil texture as humus and stabilizes moisture content. The plant nutrients in these crops are returned to the soil, thus becoming a storehouse for nutrients.
Legume plants a re hosts to nitrogen - fixing bacteria which extract nitrogen from the air and convert it into a form that can be used by plants. When used as a cover crop, legumes return the nitrogen to the soil.
Some cover crops, like oilseed radish and fava bean are deeply rooted. Their taproot is excellent at breaking apart clay, hard soils and providing much needed airspace. Cover crops planted in your garden will also serve as “living mulch” preventing erosion, nutrient loss from leaching and inhibiting weed growth.
After your garden produce is harvested, till the plant residue into the soil where it will decompose to produce more humus. This also prepares the soil for the cover crop se ed. You may use either a drop spreader, a broadcast spreader, or simply broadcast the seed by hand.
For more even coverage, make two seeding passes over the garden at right angles to each other. Lightly rake the seed into the top ¼ inch of soil. The seed m ust be covered and be in firm contact with the soil for best germination.
If you seed before fall rains begin, the seeded area should be watered lightly to keep it moist until the seeds germinate. Cover with compost for added benefit.
This cool-season grass is an annual which is adapted to late fall seeding, germinating rapidly and is tolerant of hard, difficult soils. It has excellent root mass, continues growing at low temperatures and at lower pH ranges. When tilled into the soil in spring, it adds organic matter to improve the soil texture and workability. Plant in full sun/light shade.
SOW: September through November
RATE: 1 lb. per 500 sq. ft.
Large-seeded legumes such as Austrian peas are very good for use as cover crops, building soil tilth and adding organic matter to the soil. Peas like well drained, fertile loamy soils. Highly recommended for previously worked soils. Full sun.
SOW: Plant through December.
RATE: 1 lb. per 200 sq. ft.
A summer annual, buckwheat grows rapidly, beginning to flower in as little as 5 to 6 weeks after germination. It should be tilled into the soil or cut and composted when it begins to flower. A densely growing stand of buckwheat helps shade out weeds. It is adapted to soils that are slightly acidic.
SOW: May through late October
RATE: 1 lb. per 400 sq. ft.
Less winter hardy than hairy vetch, common vetch is best adapted to well drained, fertile soils. It is not tolerant of wet soils. Vetches are annual vine type legumes with leaves ending in tendrils. An excellent nitrogen source and great for erosion control. Full sun.
SOW: Mid- September to November
RATE: 1 lb. per 400 sq. ft.
Tolerant of full sun or half shade, it will grow readily on both sandy and clay type soils, but does not grow well with poor drainage. It forms a dense green carpet by mid-winter, and matures in April. The tender vegetation is easily tilled into the soil, adding organic matter. This annual captures free nitrogen from the air and converts it to a form available to other plants.
SOW: September to mid-October
RATE: 1 lb. per 400 sq. ft.
A long-lived legume adapted to silty loam and clay soils with pH range of 6.0 to 7.0. The roots seldom grow deeper than 2 feet. Mature height: 4-8”. Tolerant of full sun or half shade.
SOW: July through November
RATE: 1lb per 2000 sq. ft.
Because Fall Rye germinates quickly and grows rapidly in cool weather, it is valuable as a cover crop. It is one of the earliest and hardiest of the cereal grains. It tolerates heavy soils, low pH and poor drainage. When grown as a cover crop it may be seeded as early as August. Takes full sun to light shade.
SOW: August through December
RATE: 1 lb. per 250 sq. ft.
Very deep rooted, this cover crop is best used in hard, previously unused soil. The taproot is excellent at breaking apart hard soil and provides much needed airspace. Winter temperatures kill off the plant, and the taproot slowly decomposes for easy tillage in the spring. Fast growing it provides quick erosion control.
SOW: September through October.
RATE: 1 lb. per 2000-3000 sq. ft.
Not really a bean, but a member of the pea family. This tall legume is vigorous, deep rooted, and an excellent nitrogen fixer. The deep taproot loosens hard soils. Best in full sun. Tolerates most soil types.
SOW: Mid to late October
RATE: 1 lb. per 350 sq. ft.
We carry a large selection of bulk cover crop seed for spring & summer planting. Spring and summer cover crops are planted after the danger of hard frost has passed. (The average last frost date in Portland is April 15)
We carry the following Cover Crop Seeds in bulk; they are sold by the pound.
Recommended seeding rates: approximate number of square feet covered by 1 pound of seed:
| Seed | Coverage |
|---|---|
| Annual Rye Grass | 500 |
| Austrian Peas | 200 |
| Buckwheat | 400 |
| Common Vetch | 400 |
| Crimson Clover | 400 |
| Dutch White Clover | 2000 |
| Fall Cereal Rye | 250 |
| Fava Bean | 350 |
The Gardenway Mixture is 30% hyoctane tritticale, 30% wheat, 28% Austrian field pea, 5% common vetch, 2% crimson clover, and 5% annual rye.
The gardener who selects this cover crop mix receives many advantages: Large amounts of organic matter from roots and leaves, when tilled under in the spring, result in improved soil tilth. Crimson clover may return enough nitrogen that many crops may be grown without the addition of other fertilizer. These crops provide competition to inhibit weed growth. Nutrient loss from leaching is reduced.
Recommended seeding rate: 1 lb. per 250 sq. ft.
