Knowledge from Olle Garden Bed: 3 Types of Green manures to Plant in Your Garden

Boost your garden naturally with green manures to prepare for the next growing season. Green manures provide a sustainable way to enhance soil and plant health in your garden, ultimately increasing crop yields for the next season. They are an excellent alternative to animal manure or harsh fertilizers, making them especially suitable for planting immediately after the last major harvest. The following content also has some reference value for raised garden beds.

Green manures are fast-growing living mulches that need at least four weeks to establish themselves and work their magic before the first frost.

From legumes to grasses to herbs, here are three types of green manures that can boost the yield of your next batch of crops.

1.Nitrogen-Fixing Green manures

Nitrogen is crucial for plant growth.

Legume green manures such as beans and peas, along with various types of clover, can supplement nitrogen in your garden. Bacteria living at the roots of these plants capture nitrogen from the air and convert it into a form that plants can use, enriching the soil and preparing it for future harvests.

For example, Midwestern farmers often use nitrogen-fixing green manures like soybeans in rotation with corn. The soybeans add nitrogen to the soil, which the corn plants will use in the next growing season.

Some common nitrogen-fixing green manures include clover, hairy vetch, crimson clover, beans, peas, and soybeans.

The ideal seeding rate varies by species, but generally, 3 to 5 pounds of seed per 1,000 square feet is recommended.

Tips: To get the full benefit, it's important to leave the roots in the soil and mix them into the cover crop as it decomposes after harvest.

Types of Nitrogen-Fixing Green manures:

Red Clover

Red clover can reduce nutrient runoff and soil erosion and is excellent for soil improvement and weed control. It often thrives in cooler conditions, such as in the northern regions of the United States.

Soil: Well-drained soil, medium to high fertility, pH level around 5.5.

Light: Full sun – at least six hours of direct sunlight per day.

Germination Temperature: Minimum germination temperature of 41°F.

Regions: Cold-hardiness zones 3a to 9a.

Hairy Vetch

Well-known for improving soil health and structure by reducing runoff and suppressing weeds. Its flowers are also pollinator-friendly. It's considered a cool-season cover crop and is typically planted at the end of summer. While it has good drought tolerance, it is sensitive to excessive moisture, which can lead to plant drowning.

Soil: Moist, well-drained soil, pH level of 6.0 to 7.0.

Light: Partial shade to full sun – four to six hours of sunlight per day.

Germination Temperature: 59°F to 73°F.

Regions: Cold-hardiness zones 4 to 10, and measures should be taken to protect it from cold weather.


Clover is fast-growing and hardy, helping break down the soil. It's cold-hardy and grows mainly in the northern and western parts of the country, making it ideal for planting in early spring or late fall.

Soil: Sandy loam, loam, and clay loam preferred, pH level of 6.8 to 7.0.

Light: Full sun – six to eight hours of sunlight per day.

Germination Temperature: 65°F to 77°F.

Regions: Cold-hardiness zones 2 to 9.

Fava Beans

As a cover crop, fava beans have the highest nitrogen-fixing rate. Soil must remain evenly moist – if it dries out, the crop will suffer and lose moisture.

Soil: Planted in well-drained loam, pH level of 6.0 to 6.5.

Light: Six hours a day.

Germination Temperature: 60°F to 65°F.

Regions: Cold-hardiness zones 4 to 8.

2.Grasses - Oats and Rye

Fast-growing weed suppressors

Several grasses are used as green manures, including winter rye, oats, and black oat grass.

Oats and rye grass help prevent erosion and inhibit weed growth.

Warning: Chemicals released during the decomposition and breakdown of rye grass may inhibit the germination of small seeds like carrots and lettuce.

Winter Rye Grass

Soil: Well-drained loam or clay loam, pH level of 5.0 to 7.0.

Light: Full sun – six hours of direct sunlight per day.

Germination Temperature: 50°F to 65°F.

Regions: Cold-hardiness zones 3 to 8.


Soil: Well-drained soil, pH level of 4.5 to 6.

Light: Full sun – six hours of direct sunlight per day.

Germination Temperature: 38°F.

Regions: Oats will grow in most areas but may not overwinter in Zone 7 or colder regions.

3.Chop and Drop Green manures

Great for returning nutrients to the soil

Chopping and dropping green manures is beneficial for restoring soil nutrients. Residue from the plants can be cut and spread throughout your garden, continuing to produce organic matter and fertilizer for your plants. While you can use nearly any plant for the chop and drop method, some plants do better than others, such as clover and comfrey.


  1. Improves soil structure.
  2. Adds organic matter to the soil as plant roots break down.
  3. Reduces water loss due to evaporation.
  4. Promotes nutrient cycling.

Tips: A good rule of thumb for when to chop and drop in your garden is when precipitation exceeds evaporation, typically during spring and fall.

Recommended Plants for Chop and Drop:

Clover: Contains high levels of nitrogen, phosphorus, and potassium, making it a nutrient-rich addition to support plant growth.

Comfrey: Comfrey helps conserve moisture, regulates soil temperature, and aids in weed management. It's rich in organic matter and helps deter pests like rodents and insects.

Green manures are fast-growing plants used to cover the soil between harvests, helping return valuable nutrients to the soil and improving its structure. If you live in a four-season climate, autumn is an ideal time to plant green manures and prepare your home garden for the upcoming spring planting.