Ashleigh Smith + photo

Ashleigh Smith

Jun 27
5 min read
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What Are Cover Crops And Green Manures Used For?

What Are Cover Crops And What Are They Good For?

Cover crops and green manures are plants grown because of their soil restoration properties to combat detrimental soil erosion. These plants can help deposit important nutrients into the soil to be used by other plants when they are grown, cut, and left to decompose into the soil. Cutting or mowing these plants before they go to seed allows their biomass to become soil again with a greater nutrient density, without becoming a weed.

Some of the most notable cover crops include plants of the legume family because they have nitrogen-fixing nodules in their root systems. These nodules host bacteria that convert nitrogen in the air into a form usable by plants in the soil. Grains can be used to produce organic matter that improves soil structure. Mustards and radishes are great at deterring pests and suppressing weeds. And broadleaf species can also help attract pollinators to your other crops.

Once fertilizers were manufactured and easily distributed cover crops began to decrease in popularity. This is because you could decide how much of each nutrient type was added to your field on demand, thus gaining more control of your crop growth. With time, using pesticides has also become more popular to prevent any plant other than your crop from growing. While these practices have contributed to many advances in agriculture, they have also led to weaker soils across the globe. There is more to your soil than just proving nutrients to your crops.

By utilizing cover crops you can reduce the amount of fertilizer needed for your growing season. In addition to reducing fertilizer applications, cover crops can increase the organic matter content of your soils and reduce the amount of pesticides needed on your fields. This means better drainage, water retention, moisture, natural pest control, and more for your money-making and life-sustaining crops. Using cover crops allows the plant components to decompose creating better soil to support your crop growth with organic pest control.

The best part of using cover crops is the long-term benefits to your soil structure. Increased organic matter means your soils retain more moisture, have better drainage, and erode at slower rates compared to the overworked soils existing across the world. If all we do is grow, grow, and grow without replenishing the basic components used to build plant material, we will deplete most of our arable land.

Cover crops are a key action that can help us return our soils to their healthiest and most productive states. For easy-to-access information take a look at our Download Free Cover Crop Growing Guide PDF. If you are a large-scale farmer, you may not see the great benefits of your cover crop efforts immediately. It can take years to fully restore soils, but the future generations farming your land with thank you immensely for putting in the work to preserve the land. Using cover crops in addition to limited or no-till methods can allow you to see faster results in your soils.

How To Grow Cover Crops:

First, identify the needs of your soil. Is it too compact with clay? Too light and dry? Have issues controlling weeds or pests?

Next, pursue the available cover crop seed offerings giving consideration to your soil needs.

Purchase your seed ahead of time as you can run into problems with stock running out during the early planting seasons.

Then, when you are ready to plant your seeds apply an inoculant to any legume seeds (Pea, vetch, bean, lentils, soybeans, alfalfa, and clover). Inoculants are treatments that give your seeds a boost of access to important bacteria responsible for processing nitrogen from the air into usable forms for the plants. Because soils have become sparse with these important soil bacterium, an inoculant gives your soil a head start as your seeds begin to sprout. Using the chart in our Free Downloadable Cover Crop Growing Guide PDF mix the correct amount of inoculant, water, and seeds together. Plant within 12 hours before your inoculant wears off.

Plant your cover crop seed using the broadcasting method.

    • Spring - Plant in the early spring and allow to grow until a few weeks before you plan to plant your crops. Mow your cover crop down.

    • Fall - Plant when summer temperatures are waning so your cover crop seeds can germinate and get enough growth during fall weather. Around the first frost or plant maturity mow down and allow to decompose over the winter.

What Are Examples Of Cover Crops And Green Manures?

While each of these crops can be used as cover crops, be sure to familiarize yourself with what is ideal for your area. A crop that is perfectly good to use in one area of the country or world may be invasive in another. Some crops are also better for some seasons than others. Because we provide seeds to many parts of the United States and some other countries we strive to provide the knowledge needed for people across many different climates and regions.

Cover Crops For Long Winters

Cover Crops For The Summer

Cover Crops For The Midwest

Garden Soil Preparation

Ashleigh Smith's photo

I'm Ashleigh Smith, a native to Northern Utah. I first gained a love of gardening with my grandmother as I helped her each summer. I decided to make a career of it and have recently graduated with a Bachelor's degree in Horticulture from Brigham Young University - Idaho. My studies have focused on plant production while I also have experience in Nursery & Garden Center Operations.


True Leaf Market

Jim, Growing anything during the hot summer months can be hard. The good thing about growing a cover crop during this time though is that you can actually prevent long-term issues like erosion, improve soil structure, and increase soil nutrients. Yes, you will need to water your cover crops during these months, however, you don’t have to feel the same devastation if these crops dry up earlier than desired. They can also be less demanding of water than other fruiting crops. The purpose of cover crops is to prevent erosion while preserving and increasing soil fertility, not to harvest a pretty crop. I would recommend planting a crop of buckwheat or sorghum, mowing it down before it goes to seed, and letting the summer heat aid decomposition. These crops are ready relatively quickly with some water. To reduce water loss apply water in the late evening and/or early morning hours. While some microbes will diminish in population during the high heat, others will flourish. You will also see more decomposition during the fall season as temperatures cool a bit. You also have the option of planting a cover crop during the fall for a boost in nutrients in time for the coming spring season with less heat stress throughout the process. Just having something over that soil throughout the summer is better than nothing. During the high summer heat exposed soils become more susceptible to wind erosion as the soil particles become lighter without moisture or root systems to hold them down. -Ashleigh


Ashleigh, My garden is divided into 3 parts. I leave one part fallow every third year and add mulch. I would like to plant a cover crop in the fallow part. However, we live in central California, where it doesn’t rain from about April to November. My understanding is that a cover crop would need to be watered in order to flourish, and I am reluctant to heavily water the fallow section of our garden because of the amount of water that we would be using during the dry season, especially now that we are in a prolonged “drought” period and we are being asked to seriously cut back on our water consumption. Do you have any suggestions? I assume that the soil microbes are inactive during the dry period also, so this would prevent the mulch from being integrated in the soil. ~ Jim