Cover crops, also called green manures, are plants sown to cover and protect soil during fallow periods. These powerful soil-building tools add organic matter, fix nitrogen, prevent erosion, suppress weeds, and support beneficial soil organisms—transforming tired soil into fertile, living earth.
Cover crops are plants sown to cover and protect soil during fallow periods. Unlike cash crops grown for food, cover crops are grown for their soil benefits and are typically terminated before or at flowering, then incorporated into the soil or left as mulch.
Common Cover Crop Categories:
- Legumes: Fix atmospheric nitrogen (clover, vetch, peas)
- Soil-Building Grasses: Add organic matter and prevent erosion (rye, oats, wheat)
- Deep-Rooted Brassicas: Break up compaction with deep taproots (radishes, turnips)
- Broadleaves: Attract beneficials and add diversity (buckwheat, phacelia)
Advertisement
Why Every Garden Needs Cover Crops:
- Add significant organic matter when incorporated
- Legumes fix 50-200 lbs nitrogen per acre for free
- Prevent soil erosion from wind and rain
- Suppress weeds through competition and allelopathy
- Break up compacted soil with deep root systems
- Feed earthworms and beneficial soil microbes
- Improve water infiltration and retention
- Reduce nutrient leaching during rainy seasons
- Provide habitat for beneficial insects
Nitrogen-Fixing Legumes
Advertisement
Crimson Clover - Beautiful red flowers, fixes 70-150 lbs N/acre, excellent for pollinators. Hairy Vetch - Vigorous vine, fixes 90-200 lbs N/acre, winter hardy. Field Peas - Fast growing, fixes 80-120 lbs N/acre, good for spring planting.
Soil-Building Grasses
Winter Rye - Extremely winter hardy, massive root system, excellent weed suppression. Annual Ryegrass - Quick establishment, dense fibrous roots, easy to terminate. Oats - Fast fall growth, winter-kills in cold climates, no spring termination needed.
Deep-Rooted Brassicas
Advertisement
Daikon Radish - Taproots penetrate 2-3 feet, break hardpan, winter-kills. Forage Turnips - Fast growing, scavenge nutrients, improve drainage. Rapeseed - Biofumigant properties, suppresses soil-borne diseases.
Fall Planting (Most Common)
Plant 4-6 weeks before first frost for winter cover crops. Rye, vetch, and crimson clover establish well in fall and provide winter soil protection.
Advertisement
Spring Planting
Plant after soil can be worked for quick biomass before summer crops. Oats, peas, and buckwheat grow rapidly in cool spring conditions.
Summer Planting
Buckwheat and cowpeas thrive in summer heat. Use between spring and fall crops or in fallow areas to prevent weed establishment.
Advertisement
Step-by-Step Planting Process:
- Fill trays with pre-moistened seed starting mix
- Create shallow depressions for seeds
- Plant seeds at depth specified on packet (usually 2x seed diameter)
- Cover with thin layer of mix and gently firm
- Mist surface and cover with humidity dome
- Place on heat mat if starting warm-season crops
- Remove dome once seeds germinate
- Position under grow lights immediately after sprouting
- Water from bottom to encourage deep root growth
- Fertilize with diluted liquid fertilizer after true leaves appear
Mowing and Incorporation
Advertisement
Mow cover crops at flowering stage, then till into soil. Wait 2-3 weeks before planting to allow decomposition. Best for adding maximum organic matter.
Roller-Crimping
Roll mature cover crops flat to create mulch layer for no-till planting. Requires specialized equipment but preserves soil structure.
Winter-Kill
Advertisement
Choose species that die naturally in winter (oats, daikon radish). No spring termination needed—simply plant through residue.
These quality cover crop seeds will improve your soil:
Recommended Products
Crimson Clover Cover Crop Seeds (5 lbs)
$34.99
PROS
- Fixes 100+ lbs nitrogen/acre
- Beautiful pollinator flowers
- Easy to establish
CONS
- Needs fall planting in most zones
- Can reseed if not terminated early
Winter Rye Cover Crop Seeds (10 lbs)
$29.99
PROS
- Extremely winter hardy
- Massive root system
- Excellent weed suppression
CONS
- Can be difficult to terminate
- Allelopathic effects on some crops
Garden Cover Crop Mix (3 lbs)
$24.99
PROS
- Balanced legume and grass mix
- Multiple soil benefits
- Easy for beginners
CONS
- Smaller quantity for large areas
- Mix ratio not customizable
As an Amazon Associate, we earn from qualifying purchases. Affiliate ID: blogguru0e-20
Advertisement
Frequently Asked Questions
How long before planting should I terminate cover crops?
Wait 2-3 weeks after incorporating cover crops before planting. This allows initial decomposition and prevents nitrogen tie-up. For no-till systems with surface mulch, you can plant immediately after rolling.
Can I plant cover crops in raised beds?
Absolutely! Cover crops work wonderfully in raised beds. Use lower seeding rates and choose compact varieties. Winter rye, crimson clover, and field peas are excellent choices for small-space gardening.
Do I need to inoculate legume cover crop seeds?
Yes, for maximum nitrogen fixation. Legumes need specific rhizobium bacteria to form nitrogen-fixing nodules. Purchase the correct inoculant for your legume species and apply just before planting.
Will cover crops attract pests to my garden?
Cover crops generally attract beneficial insects that prey on pests. However, some brassica cover crops can harbor cabbage pests. Rotate cover crop families just as you would vegetable crops.
Advertisement
Related Articles
Written by
Dr. Sarah Mitchell
Soil scientist with 15 years of experience in agricultural research and sustainable gardening practices.