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How to Grow Cover Crop Legumes

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Cover Crop Legumes

Fabaceae family (various species)

herb

Cover crop legumes are nitrogen-fixing plants from the bean and pea family, grown primarily to improve soil health rather than for harvest. These fast-growing plants prevent erosion, suppress weeds, and enrich soil with bioavailable nitrogen through symbiotic relationships with rhizobia bacteria in root nodules. Commonly used species include clover, alfalfa, vetch, and field peas.

Looking for a specific variety?

White Clover Red Clover Crimson Clover Alfalfa Hairy Vetch Austrian Winter Pea

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Example Cover Crop Legumes timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Cover Crop Legumes

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Cover Crop Legumes

    Around May 17

    ≈ 30 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Cover Crop Legumes dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6+ hours daily; tolerates partial shade
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Water: Moderate moisture; 1-2 inches per week; drought tolerant once established, especially alfalfa and clover varieties
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Spacing: Variable; broadcasting at 20-30 lbs/acre (or 1-2 lbs per 1000 sq ft for small gardens) inches
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Days to maturity: 30-120 days depending on species and purpose; typically 60-90 days for biomass accumulation
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Planting depth: 0.25-0.5 inches for small seeds; 1-1.5 inches for larger legume seeds

Soil

Type: Well-draining loamy to clay loam soil; adaptable to various soil types
pH: 6.0-7.5
Amendments:
Inoculant containing appropriate Rhizobium bacteria species Phosphorus and potassium if soil testing indicates deficiency Compost for organic matter improvement Lime in acidic soils below pH 6.0

Growing Zones

Find your zone →

Varies by species; cool-season types thrive in zones 2-7, warm-season types in zones 5-10

2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b

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Growth Stages

1

Germination

5-10 days

Seeds absorb moisture and begin sprouting; cotyledons emerge from soil

Keep soil consistently moist but not waterlogged; avoid compacting soil; ensure good seed-to-soil contact

2

Seedling & Establishment

3-4 weeks

True leaves develop; root systems establish including initial nodule formation with rhizobia bacteria

Maintain adequate moisture; avoid heavy foot traffic; suppress competing weeds by gentle cultivation or flame weeding; inoculated seed is critical at this stage

3

Vegetative Growth

4-8 weeks

Rapid shoot and root development; plants fill in and cover bare soil; nitrogen fixation increases as nodule biomass builds

Monitor for pest pressure; minimal fertilizer needed due to nitrogen fixation; allow unrestricted growth for maximum biomass

4

Flowering

2-4 weeks

Plant produces characteristic legume flowers (pea-like); peak nitrogen accumulation occurs; high biomass and organic matter

Do not harvest or graze at this stage if continuing as cover crop; some growers choose to terminate before seed set to prevent volunteer plants

5

Termination & Incorporation

Variable; incorporation 2-4 weeks before next planting

Plant dies back and decomposes; nitrogen becomes available to following crops; organic matter enriches soil structure

Terminate by mowing, tilling, or herbicide (for non-organic systems); allow 2-4 weeks before planting cash crop for decomposition; roller-crimper method minimizes soil disturbance

Companion Planting

Plan your garden →

Plant with:

Grasses (in mixed cover crop blends) Rye (cool-season mix) Oats (cool-season mix) Buckwheat (summer mix) Radish (tillage radish for soil structure)

Avoid planting near:

Other legumes in rotation (may compete for rhizobia or increase pest pressure) Crops susceptible to legume-specific diseases

Common Pests

  • Rotate cover crops; incorporate biomass deeply; allow winter kill in cold climates; biological control with parasitoid wasps

  • Clip or mow to disrupt life cycle; rotate species; select resistant varieties if available

  • Encourage beneficial insects (ladybugs, parasitoid wasps); spray with neem oil if severe; generally not problematic in cover crop settings

  • Early spring mowing to reduce adult populations; species rotation

Uses

🍳

Edible Sprouts & Greens

Culinary

Young legume plants can be harvested as nutritious microgreens or tender shoots for salads. Species like clover and alfalfa are commonly sprouted for salads and garnishes. [source]

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Nutritional Supplements

Medicinal

Alfalfa and clover have been used in herbal medicine for centuries; alfalfa sprouts are rich in vitamins K, C, and minerals. These plants contain beneficial phytoestrogens and saponins with potential health benefits. [source]

🏠

Nitrogen Fixation & Soil Amendment

Household

The primary use of cover crop legumes is improving soil fertility by fixing atmospheric nitrogen through symbiotic rhizobia bacteria. A well-established legume cover crop can add 100-300 lbs of nitrogen per acre, reducing or eliminating the need for synthetic fertilizers. [source]

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Erosion Control & Soil Structure

Household

Dense legume growth prevents water and wind erosion on exposed soil. After incorporation, their organic matter improves soil structure, water infiltration, and microbial activity. [source]

🦋

Forage & Pollinator Support

Wildlife

Legume cover crops provide valuable forage for livestock and wildlife. Flowering legumes attract and support bees, butterflies, and beneficial insects, enhancing pollinator populations and biodiversity. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Cover crops are not typically harvested for yield; instead, they are grown to termination. Terminate by mowing when 50% in bloom (optimal nitrogen content), or allow to mature for maximum biomass. Incorporate into soil 2-4 weeks before planting the next crop to allow decomposition. Grazing animals can harvest the biomass directly, returning nutrients via manure. For seed saving, allow selected plants to mature fully, dry, and thresh.

Fun Facts

  • 🌱 A single legume plant can fix 100-300 lbs of nitrogen per acre per season through the action of Rhizobium bacteria living in root nodules—equivalent to 200-600 lbs of synthetic nitrogen fertilizer.
  • 🌱 The relationship between legumes and Rhizobium bacteria is a classic example of mutualism: the plant provides carbohydrates to the bacteria via photosynthesis, while bacteria provide bioavailable nitrogen to the plant.
  • 🌱 Ancient farmers practiced crop rotation with legumes over 2,000 years ago, long before the science of nitrogen fixation was understood—demonstrating the timeless agricultural wisdom of using cover crops for soil restoration.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Cover Crop Full Sun Partial Shade True Leaves
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