What are cover crops and why you need them

Cover crops, also known as green manures, are plants grown for the purpose of improving soil health and fertility. They are an essential component of sustainable agriculture and gardening and offer numerous benefits to the environment and crops.

This article is part 5 and the last of the Starting a Garden Series, where we go through the most important aspects of gardening so you can start with some information under your belt.

Previously we discussed the importance of Soil Health in the garden, and cover crops are a great way to start amending a new land space, specially one that seems infertile and lacking soil structure.

In this article, we will discuss the use of cover crops in the garden and how they can improve soil health and productivity.

Photo by Glenn Carstens-Peters

What are Cover Crops?

Cover crops are a type of plant that is grown specifically to improve soil health and fertility. They are often sowed as seeds in the fall as garden beds become empty or early spring before it’s warm enough to plant anything else. They provide a source of organic matter, reduce soil erosion, and prevent nutrient loss. Cover crops are typically grown for a few months, after which they are tilled under to improve soil structure, fertility, and water-holding capacity.

Benefits of Cover Crops

1. Soil Improvement: Cover crops are a great way to start recovering a dead piece of land. They help improve soil structure and fertility by adding organic matter to the soil. This organic matter helps to retain moisture, increase soil porosity, and improve soil tilth. The roots of cover crops also help to aerate the soil and break up compacted soil layers, allowing water and air to penetrate more easily.

2. Erosion Control: Cover crops help to reduce soil erosion by providing a protective cover for the soil. The plants hold soil in place and prevent water from carrying away valuable topsoil. This is particularly important in areas with high rainfall or steep slopes.

3. Nitrogen Fixation: Many cover crops, such as legumes, are nitrogen-fixing plants. This means that they are able to take nitrogen from the air and convert it into a form that is usable by plants. This helps to reduce the need for synthetic nitrogen fertilizers and improve soil fertility.

4. Weed Suppression: Cover crops can help to suppress weeds by shading out weed seedlings and reducing the amount of bare soil available for weed germination.

5. Pest Management: Cover crops can help to reduce the number of pests and diseases in the garden by providing habitats for beneficial insects and increasing soil health. This, in turn, helps to reduce the need for synthetic pesticides and herbicides.

Photo by Rafay Ansari

Types of Cover Crops

There are many different types of cover crops, each with its own set of benefits. Some common cover crops include:

1. Legumes: Legumes, such as clover, beans, and peas, are nitrogen-fixing crops that pull nitrogen from the air and and add it to the soil improving soil fertility.

2. Grass Crops: Grass crops, such as rye and wheat, are fast-growing and help to improve soil structure and reduce soil erosion.

3. Brassicas: Brassicas, such as mustard and radish, are fast-growing and help to improve soil structure and reduce soil erosion. They also produce compounds that suppress the growth of certain pests and diseases.

4. Buckwheat: Buckwheat is a fast-growing cover crop that can improve soil fertility and suppress weeds.

Using Cover Crops in the Garden

Cover crops can be used in a variety of ways in the garden, including:

1. In between growing seasons: Sow cold hardy cover crop seeds in late fall or early spring once the soil can be worked on. Let the plants grow until you’re ready to plant warm loving plants like tomatoes and peppers. At that time, chop the cover crop and mix it into the soil, adding a layer of compost to your garden beds. Now you are ready to plant your garden beds in soil full of health and organic matter.

2. As a weed suppressant: Cover crops can be used to suppress weeds by shading out weed seedlings and reducing the amount of bare soil available for weed germination. Sow cover crop seeds under fruit trees and other plants wherever you want to suppress weeds.

3. As a soil-improvement crop: Cover crops can be grown specifically to improve soil health and fertility. The plants are tilled under after a few months to add organic matter to the soil. Sow legume cover crop seeds around heavy feeder plants like brassicas, tomatoes and eggplant. Let them grow for two months and then chop and mix in with the soil to add nutrients to your soil.

Photo by Markus Spiske

Cover Crop Seeds by Use

Nitrogen fixation

• Red Clover

• Crimson Clover

• Hairy Vetch

• Austrian Winter Peas

• Fava Beans

Soil improvement

• Buckwheat

• Annual Ryegrass

• Winter Rye

• Oilseed Radish

• Tillage Radish

Erosion control

• Annual Ryegrass

• Winter Rye

• Crimson Clover

• Hairy Vetch

• Oats

Weed suppression:

• Winter Rye

• Hairy Vetch

• Buckwheat

• Annual Ryegrass

• Sorghum-Sudangrass

Pest control

• Sunn Hemp

• Mustard

• Buckwheat

• Oats

• Sorghum-Sudangrass

Pollinator support

• Crimson Clover

• Buckwheat

• Phacelia

• White Dutch Clover

• Sweet Alyssum

Cold hardy

• Winter Rye

• Winter Wheat

• Crimson Clover

• Hairy Vetch

• Austrian Winter Peas

This concludes the Starting a Garden Series. I hope this information was helpful to you as you plan your garden and spend your warm days outdoors caring for it.

Also on this series:

1. Want to start gardening? Here’s how.

2. Soil health and why your plants aren’t growing

3. How to start seeds indoors for your garden

4. How to start composting at home