← Plant Guides

How to Grow Legumes (Nitrogen-Fixing Cover Crops)

Wikimedia Commons

Legumes (Nitrogen-Fixing Cover Crops)

Fabaceae family - Desmodium spp., Centrosema spp., Pueraria spp.

vegetable

These nitrogen-fixing legumes are grown primarily as cover crops and green manures to enhance soil fertility through symbiotic relationships with rhizobia bacteria. Desmodium, Centrosema, and Pueraria are tropical and subtropical legumes valued for erosion control, weed suppression, and sustainable agriculture practices. They accumulate atmospheric nitrogen in the soil, improving crop productivity in subsequent plantings.

When should you plant Legumes (Nitrogen-Fixing Cover Crops) in your zone?

Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.

Get my Legumes (Nitrogen-Fixing Cover Crops) timeline →

Example Legumes (Nitrogen-Fixing Cover Crops) timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Legumes (Nitrogen-Fixing Cover Crops)

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Legumes (Nitrogen-Fixing Cover Crops)

    Around Jul 16

    ≈ 90 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Legumes (Nitrogen-Fixing Cover Crops) dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6-8 hours daily; tolerates partial shade
💧
Water: Moderate water needs; establish with regular watering, then drought-tolerant once established. Desmodium and Centrosema are drought-resistant; Pueraria requires consistent moisture
📏
Spacing: 12-24 inches apart depending on species and intended use; broadcast seeding at 15-25 lbs/acre for cover crops inches
📅
Days to maturity: 90-150 days to flowering; 180-240 days to seed maturity
🌱
Planting depth: 0.5-1 inch for seeds; plant in spring after frost danger or at onset of rainy season

Soil

Type: Well-draining loamy to sandy soil; tolerates poor soils
pH: 5.5-7.5
Amendments:
Inoculant with Rhizobium bacteria (essential for nitrogen fixation) Compost or aged manure for initial establishment Lime if pH below 5.5 Phosphorus and potassium for nodule formation

Growing Zones

Find your zone →

Thrives in zones 9-12; Desmodium tolerates cooler conditions (zone 8); Pueraria prefers warmer tropical regions (zones 10-12)

9a 9b 10a 10b 11a 11b 12a 12b

Sign up free to see if Legumes (Nitrogen-Fixing Cover Crops) grows in your zone — and get a personalized planting timeline.

Get my Legumes (Nitrogen-Fixing Cover Crops) timeline →

Growth Stages

1

Seedling/Establishment

3-4 weeks

Emerging cotyledons and first true leaves appear; plant is establishing root system and nodule formation begins

Ensure adequate soil moisture for germination; inoculate soil with appropriate Rhizobium strain before planting; protect from heavy traffic or grazing

2

Vegetative Growth

6-8 weeks

Rapid leaf and stem development; plant expands canopy and root system deepens; nitrogen fixation increases with nodule maturation

Monitor for early pests; avoid nitrogen fertilizer which inhibits nodulation; allow adequate spacing for air circulation

3

Flowering

4-6 weeks

Abundant purple, pink, or white flowers appear along stems; peak nitrogen fixation occurs during flowering

Increase watering during dry periods if necessary; pollinator activity increases; do not apply herbicides during flowering

4

Pod Development & Maturation

6-8 weeks

Seed pods form and fill; plant prepares to senesce; nitrogen accumulation is highest at this stage

Reduce watering to allow senescence; avoid harvesting fodder if nitrogen return is the primary goal

5

Senescence & Incorporation

2-4 weeks after incorporation

Plant dies back and biomass decomposes in soil; accumulated nitrogen becomes available to subsequent crops

Chop or plow under biomass 2-4 weeks before planting main crop; allow decomposition time for nutrient release

Companion Planting

Plan your garden →

Plant with:

Grasses (for improved forage quality) Corn (in rotation) Rice Cassava Maize Alley cropping with tree species

Avoid planting near:

Other nitrogen-fixing legumes (in same season, reduce diversity) Heavy nitrogen-feeding crops planted simultaneously (disrupts ecological balance)

Common Pests

  • Hand-pick; encourage natural predators; plant-derived insecticides if severe

  • Monitor for infestations; use Bt (Bacillus thuringiensis) if economically justified

  • Early harvest if seed production intended; incorporate residue promptly

  • and

    Tolerated at low levels; increase with water stress; improve irrigation

  • Usually not economically damaging on cover crops; monitor for virus transmission

Uses

🍳

Nutritious Animal Fodder

Culinary

Young leaves and stems of Desmodium and Centrosema are highly nutritious forage for cattle, goats, and sheep, with high protein content (15-25%) and palatability. Pueraria is extensively used as elephant grass in tropical regions. [source]

💊

Traditional Medicine

Medicinal

Desmodium species have been used in traditional African and Asian medicine to support liver function and treat digestive ailments. Pueraria (kudzu) root contains compounds studied for menopausal and metabolic health benefits. [source]

🏠

Nitrogen Fixation & Soil Fertility

Household

The primary agronomic use: nitrogen-fixing bacteria in root nodules convert atmospheric N₂ into plant-available nitrogen (up to 200-300 lbs N/acre annually), eliminating the need for synthetic nitrogen fertilizers. This reduces input costs and environmental impact. [source]

🎨

Erosion Control & Land Rehabilitation

Craft

These deep-rooted legumes stabilize slopes, prevent soil erosion, and suppress weeds in degraded lands. Their use in alley cropping and agroforestry systems improves land productivity and carbon sequestration. [source]

🦋

Pollinator & Wildlife Support

Wildlife

Abundant flowers attract bees, butterflies, and other pollinators, supporting biodiversity. Dense growth provides habitat and food for beneficial insects and small wildlife in agricultural landscapes. [source]

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

Harvest Tips

For nitrogen fixation benefit: Incorporate into soil 2-4 weeks before planting main crop at full flowering or early pod stage for maximum nitrogen content. For fodder use: Cut 4-6 weeks after planting for nutritious livestock feed while maintaining regrowth capability. For seed production: Allow full maturation, then harvest pods when dry and brittle, thresh to extract seeds.

Fun Facts

  • 🌱 A single legume plant can fix 100-200 pounds of nitrogen per acre per year through its symbiotic partnership with Rhizobium bacteria in root nodules—a natural nitrogen factory more efficient than many synthetic fertilizers.
  • 🌱 Pueraria (kudzu) grows so vigorously that a single plant can spread 3-5 feet in one growing season; while valuable for erosion control in some regions, it is considered invasive in North America due to its aggressive growth.
  • 🌱 Desmodium has been used in push-pull agricultural systems in East Africa to suppress parasitic weeds (Striga) and repel stemborers, demonstrating how a single cover crop can address multiple pest management challenges simultaneously.

Gardening Terms

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

Cover Crop Full Sun Germination Green Manure Partial Shade pH True Leaves
Shop Legumes (Nitrogen-Fixing Cover Crops) plants and related plants at Plant Addicts →

Join 30,000 gardeners planning their gardens with LizPlants.

Get your personalized Legumes (Nitrogen-Fixing Cover Crops) planting timeline

Tell us your zip code and we'll calculate exactly when to start Legumes (Nitrogen-Fixing Cover Crops) seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.

Get my Legumes (Nitrogen-Fixing Cover Crops) timeline →