Planting cover crops is a powerful way to improve your soil. Cover crops perform a host of valuable functions like increasing soil organic matter, fixing nitrogen, breaking up compaction, suppressing weeds and preventing erosion. In this guide we'll discuss your options for spring cover crops and the benefits of each, when and how to plant, and how to manage the crop once it's established.

While commercial growers typically use a seed drill or mechanical broadcaster to plant cover crops (followed by mowing and tilling before the crop sets seed), home gardeners can grow cover crops too. For gardeners we recommend planting most cover crops by hand-broadcasting seed over freshly turned soil, then raking in lightly just before a rain. When the cover crop is in flower, just before it sets seed, it should be cut with a scythe or mower, then left as a living mulch for the rest of the season or turned under with a rototiller. Because of the nutrients bound up by the decomposing crop, it is recommended to wait 2-3 weeks after tilling before planting another crop into the area. At this point the cover crop residues will have mostly decomposed, making organic matter and nutrients available to the next crop.

BMR Sorghum-Sudangrass F1

Life cycle: Annual

Benefits: fast growing, tolerates drought, builds biomass, smothers and discourages weeds, penetrates compact soil. Can grow to 12’ tall with 4,000-5,000 lbs of dry matter produced per acre, easier to grow than corn (for silage)

Uses: soil building, silage or green forage when 24-30” tall (not suitable for horses)

When to sow: Late May to early July depending on location, or when soil reaches 60ºF

Days to maturity: 90-100

Seeding rate and depth: 35 lbs/acre drilled or 40-50 lbs/acre broadcast, .5” deep in heavy soil, 1.5” deep in sandy soil

How to harvest: Mow when crop reaches 36-40” tall for silage

Limitations: soil temperature must reach 65ºF at least two months before first fall frost. Performs poorly in waterlogged soils

Learn more about Sorghum-Sudangrass for silage here

 

Common Buckwheat

Life cycle: Annual

Benefits: a rapid grower widely used for smothering weeds, lightening heavy soils, holding nutrients for the next crop and attracting pollinators

Uses: as a green manure in rotation with vegetable crops, for grain

When to sow: late May through July or when soil is at least 50ºF, at least 3 months before first frost for grain

Days to maturity: 35-42 bloom, 70-84 grain

Seeding rate and depth: 2-3 lbs/1000 sq ft or 35-135 lbs/acre

How to harvest: for green manure mow or harrow before seeds mature, about one month after planting. For grain cut when 80-90% of seeds have turned brown, after killing frost

Limitations: does not tolerate waterlogged soils or very hot, dry weather (later planting is recommended for Southern growers to avoid the hottest part of the summer)

Learn more about Buckwheat for grain production here

 

Medium Red Clover

Life cycle: Perennial

Benefits: fixes nitrogen, mines nutrients & conditions soil, tolerates shade, reduces compaction, attracts beneficial insects, tolerates poor/wet/acid soils, produces 2-4 tons dry matter/acre in 2nd year

Uses: soil builder, ground cover, undersown in existing crops, insectary, hay and forage

When to sow: Spring to summer when soil is above 41ºF

Days to maturity: 14 months when spring sown

Seeding rate and depth: Broadcast, drilled or frostseeded 1/2 lb/1,000 sq ft or 5-15 lbs/acre, ¼-1/2” deep

How to harvest: Incorporate once blooming begins in spring of 2nd year by mowing and/or tilling under

Limitations: not exceptionally heat-tolerant; growers in the South should plant in late summer/fall for overwintering

TIP: “Frostseeding” can be effective at least a month before last frost; sow in early morning when soil is still frost-covered

 

Field Peas

Life cycle: Annual

Benefits: fixes nitrogen, builds soil, moderate weed suppression, biomass decomposes quickly, edible tops

Uses: soil builder, edible tendrils, forage crop

When to sow: Early spring as soon as soil can be worked

Days to maturity: 52-75

Seeding rate and depth: 5 lbs/1,000 sq ft or 200 lbs/acre, 1 ½ to 3” deep

How to harvest: Till when flowering begins

Limitations: does not tolerate hot, dry conditions; growers in the South should use as fall/winter crop in areas where legumes have not been grown recently

TIP: Oats support weak pea stems and act as a “nurse” crop; sow 120 lbs of peas with 2 bushels of oats per acre

 

Improved White Clover

Life cycle: Perennial

Benefits: fixes nitrogen, reduces compaction, improves soil health, tolerates mowing/trampling/wet soils/drought

Uses: soil builder, excellent for paths and lawns, undersow around existing crops for living mulch, green manure, hay, pasture forage

When to sow: Anytime, preferably before a rain

Days to maturity: 60-70

Seeding rate and depth: ¼ lb/1,000 sq ft, 5-9 lbs/acre drilled, 7-14 lbs/acre broadcast then rolled, raked or cultivated to ensure good soil contact

How to harvest: Chisel or moldboard plow to kill; regular mowing to maintain

Limitations: Slow to establish, not ideal for smothering weeds.

TIP: Combine with Annual Ryegrass to increase soil benefits. “Frostseeding” can be effective a month before last frost; sow in early morning when soil is still frost-covered

 

Oats

Life cycle: Annual

Benefits: fast grower, prevents erosion, suppresses weeds, scavenges nutrients, builds biomass with up to 8,000 lbs/acre dry matter from spring stands

Uses: soil builder, nurse crop for legumes, green manure, grain, hay

When to sow: Early spring to summer, when soil is at least 38ºF

Days to maturity: 100-120 for grain

Seeding rate and depth: Broadcast or drill 4 lbs/1,000 sq ft or 100-140 lbs/acre 1” deep

How to harvest: Till in when seedheads are just forming, or cut grain when seeds harden

Limitations: performs poorly in hot, dry weather; Southern growers should plant in fall

 

Annual Ryegrass

Life cycle: Annual

Benefits: fast grower, suppresses weeds, controls erosion, adds organic matter, catches nutrients, thrives in all soil types

Uses: soil builder, nurse crop, emergency forage

When to sow: Anytime soil is at least 40ºF

Days to maturity: 50-70

Seeding rate and depth: Broadcast 20-30 lbs/acre or drill 10-20 lbs/acre ½” deep

How to harvest: Disk, till or plow under as soon as flowers form

Limitations: occasionally some plants overwinter and become weedy

 

Yellow Sweet Clover

Life cycle: Biennial

Benefits: nitrogen-fixer, mines nutrients from deep in soil, drought-tolerant, attracts beneficials, tolerates poor soil, adds up to 2.5 tons dry matter/acre in first year

Uses: excellent green manure, soil builder, subsoil aerator, and honey plant

When to sow: Spring to summer when soil is at least 42ºF

Days to maturity: 60-70 to bloom

Seeding rate and depth: Broadcast ½ lb/1,000 sq ft or 15-20 lbs/acre, drill 8-15 lbs/acre

How to harvest: Kill early in 2nd year by mowing or tilling when stalks are 6-10” tall

Limitations: does not tolerate waterlogged soil; recommended for fall in the South

TIP: Best grown with 2 bushels of oats as a nurse crop

 

Field Peas/Oats Mix

Life cycle: Annual

Benefits: versatile, fixes nitrogen, builds soil, suppresses weeds, decomposes quickly, edible pea tendrils

Uses: versatile soil builder, marketable pea tendrils, forage crop

When to sow: Early spring when soil is at least 38ºF

Days to maturity: varies

Seeding rate and depth: Broadcast 5 lbs/1,000 sq ft or 200 lbs/acre and rake or cultivate

How to harvest: till under or otherwise incorporate before seeds are set

Limitations: peas do not tolerate very hot dry weather; may be grown as a fall crop in the South

 

Field Peas/Oats/Vetch Mix

Life cycle: Annual

Benefits: versatile, fixes nitrogen, suppresses weeds, decomposes quickly, edible pea tendrils, adds up to 8,000 lbs/acre of organic matter

Uses: versatile green manure, soil builder, marketable pea tendrils, forage crop

When to sow: Early spring when soil is at least 38ºF

Days to maturity: varies

Seeding rate and depth: Broadcast 6-8 lbs/1,000 sq ft or 210 lbs/acre and rake in

How to harvest: till under or otherwise incorporate before seeds are set

Limitations: peas do not tolerate very hot dry weather; may be grown as a fall crop in the South