Cover Crops and Green Manures

NOTE: Cover crops reduce erosion, sequester nutrients and compete against weeds. When worked into the soil, they are called green manures.

Seeding Rates and Reasons for Use

Crop — Major Reasons for Use	Lbs per 1000 sq. ft.	Lbs per acre
Buckwheat — Good scavenger of soil phosphorus; controls weeds; mow before seeds develop.	1.0 – 2.0	50 – 60
Clover, Berseem — Full-summer crop; good weed control.	0.33 – 0.5	15 – 20
Clover, Crimson — Quick summer cover crop.	0.5 – 0.75	20 – 30
Clover, Red — Adds nitrogen; adds organic matter; shade tolerant; slow early growth.	0.25	08 – 12
Millet, Japanese — Controls weeds; adds organic matter.	1.0	30 – 40
Oats — Seed 30-40 days before first fall frost if using as winter cover crop; controls weeds.	2.5	90 – 100
Field pea / Vetch / Oat — Adds nitrogen and organic matter; lush growth provides excellent weed control.	5.0	200
Rye, Winter — Winter cover crop regrows in spring; can sow later than others; drought-tolerant.	2.0	90
Rye, Annual (also called Italian Rye) — Winter cover crop; controls weeds; can be sown between established rows of corn.	0.5 – 1.0	25 – 35
Sudangrass or Sorghum-Sudangrass — Control weeds; add organic matter; heat- tolerant; drought-tolerant; grows 6-8’ tall.	1.0	30 – 40
Vetch, Hairy — Strong nitrogen fixer; drought-tolerant; slow early growth.	1.0 – 1.5	50 – 60

When to Sow; When and How to Incorporate

Crop	When to Sow	When to Incorporate; Tools to Incorporate Into Soil
Buckwheat	Early summer	Late summer Tiller; can also fork in by hand
Clover, Berseem	Spring	Late summer to fall while green; or next spring after winterkill Tiller or spade (may mow first)
Clover, Crimson	Spring	Late summer to fall while green; or next spring after winterkill Tiller or spade (may mow first)
Clover, Red (2-season crop)	Late spring … Summer …	… Spring of the next year … Fall of the next year Tiller; can also fork in by hand
Millet, Japanese	Late spring … Summer …	… Late summer … Fall Tractor
Oats	Early summer … Late summer …	… Fall … Spring of the next year Tiller; can also fork in by hand
Field pea – Vetch – Oat	Spring or early summer	Late summer Tiller; can be difficult to incorporate
Rye, Winter	Late summer or early fall	Spring of the next year Tractor or large tiller
Rye, Annual	Spring … Fall …	… Fall … Spring of the next year Tiller
Sudangrass or Sorghum-Sudangrass	Early summer	Fall Tractor (can be challenging in home garden or tight cropping schedule)
Vetch, Hairy	Spring … Fall …	… Fall … Spring of the next year Tractor or large tiller

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From the GardenPro Answer Book; revised and updated by Lois Berg Stack, Ornamental Horticulture Specialist, University of Maine Cooperative Extension.