How to Use Cover Crops

Using cover crops is simple once you understand what they are, how they work, how to remove them, and the benefits. I hope this guide helps you to feel confident in learning how to use cover crops.

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What are Cover Crops?

Cover crops have a very different purpose than a normal vegetable or fruit planting. Instead of growing fruit, vegetables, or seeds for harvest and consumption, a cover crops’ main job is to improve the soil.

What is the difference between plants used as cover crops and plants used for eating?

Some plants can be used for both. For example, rye is often planted to harvest the grain but rye is also planted as a cover crop.

Here is the difference: rye planted for a harvest of grain matures long enough to develop seed. Rye planted as a cover crop must be terminated before it’s able to set seeds in order to maximize its positive benefits.

Why you Should be Planting Cover Crops and Benefits of Cover Crops

Often in gardening, we think in terms of supplements like fertilizers and powders to ensure plant nutrition. But healthy plants don’t just come from supplements, they come from healthy, living soil. Cover crops are a natural and often more affordable way to improve the health of your soil.

Here are some of the benefits of planting cover crops:

Control Pests
Control Diseases
Attract beneficial insects
Fixing Nitrogen in the soil naturally
Weed Suppression
Increase Biodiversity.
Sequester more carbon
Increase beneficial microbes in the soil
Reduce erosion
Add organic matter

Individual cover crops have specific benefits and they are not all created equal. Using rye as an example again, its benefits are loosening topsoil, it has allelopathic effects meaning it doesn’t allow seeds from other plants to sprout. It also chokes out weeds, fights erosion, and adds biomass (organic matter from decomposing plants) to the soil.

On the other hand, crimson clover attracts beneficial insects, is good for grazing, provides nitrogen, and also prevents erosion.

Both are beneficial in different ways. Each should be utilized based on what is needed to improve the soil.

Compost Vs. Cover Crops

Aside from all the obvious benefits mentioned above, some wonder why you would plant a cover crop, rather than simply adding compost?

The answer to that has a lot to do with soil. The soil is filled with millions of microorganisms and living creatures. While compost does feed soil microbes, it doesn’t have the same benefits as living roots.

Living roots make soil microbiology explode in growth, giving a consistent source of food for the soil food web. They are also directly responsible for healthy soil creation.

sudangrass, buckwheat, cow pea cover crop — Summer cover crop: Sudangrass, buckwheat, and cowpeas

Though I am not a soil microbiology scientist, I have seen both in the soil, and by what’s happening in the plants above, the difference between plants grown right after a cover crop and plants grown after only compost has been applied.

Plants grown after cover crops thrive for longer and are generally healthier than plants grown in compost alone.

However, the best soil doesn’t come from choosing compost or cover crops, it’s by implementing both compost and cover crops to your home garden to add life to the soil.

What cover crop should I plant and when?

Below you’ll find a table of commonly used cover crops, when the best season is to grow them, the type, some benefits, and if they winterkill.

What type of Cover Crop is Best for the Home Garden?

Fixating on one specific cover crop to grow is actually not the best method. Nature always has diversity, therefore it is best to plant a cover crop mix with at least three different plant species in the mix.

The best combinations are different types of plants for example, a cereal, a legume, and a brassica. Or a cereal and two legumes.

In general, legumes will fix nitrogen into the soil. “Fixing nitrogen” means it converts from atmospheric nitrogen to form available to plants. This is vital because nitrogen is essential for field crops. Source

Summer Cover Crop Home Garden — Buckwheat and Sudangrass Cover Crop

Nitrogen can be lost very quickly, therefore, I commonly add legumes to fix nitrogen from the atmosphere since the plants need it and it is a more natural method to add nitrogen back to the soil.

Crops mixed with the legumes are utilized for different reasons like adding biomass, acting as a nurse crop, or breaking up soil (see chart above).

I have some of my own favorite cover crop mixes, but feel free to make your own. The important thing to remember is to group plants by season in which they grow best, and if they mature around the same time, since you’ll be removing them all at once.

My favorite cover crop mixes

Spring cover crop mix: Field peas, oats, and field radish

Summer cover crop mix: Sudangrass, cow peas, and buckwheat

Fall cover crop mix: Winter rye, crimson clover, and hairy vetch

cover crops mix — Winter rye, crimson clover, and hairy vetch

When to Terminate a Cover Crop

In the book Managing Cover Crops Profitably, by the Sustainable Agriculture Research and Education Program (SARE), they say “Timing of cover crops termination affects soil temperature, soil moisture, nutrient cycling, tillage and planting operations and the effects of allelopathic compounds on the subsequent cash crop. Because of the many factors involved, decisions about when to kill the cover crop must be site- and situation-specific.”

While that is true, and super important to a farmer looking to increase profits, as a home gardener I have a simple rule of thumb: terminate a cover crop within ten days of seeing flowers. This allows for the full benefits to take place but the seeds will not have formed.

Obviously there are a few crops like brassicas that will not fit into that rule of thumb because most of the time you’ll want to remove them before they flower.

You can remove a cover crop earlier as well. Earlier removal can be beneficial because the cover crop is young and strong and less likely to have disease and it speeds decomposition.

How to Terminate Cover Crops in the Home Garden Organically

There are several ways to terminate a cover crop in the home garden organically, without using herbicides.

Here are some ways to kill a cover crop naturally:

1. Crimp and tarp

I have an example of how to crimp and tarp in a Youtube video HERE. We use human power and a Tpost laid horizontally and tied with string that we use to lift it up and down. Then we press and crimp the crop with our weight. We use a silage tarp (my favorite can be found HERE) to cover it then let it sit until the crop is brown. The time for that to happen varies based on what time of year it is. But usually about 2-3 weeks is sufficient.

2. Mow and tarp

I recently got a flail mower attachment for our BCS and it’s awesome. It doesn’t just slice a crop, it chops it up small. Then the remaining material decomposes very fast. Cover the entire area with a silage tarp until fully terminated.

3. Pulling the cover crop out and laying it on the soil

This method would be last on my list because much of the benefit of the cover crop is also in the roots. If you pull out the whole plant with the roots to kill it you’re losing some of the benefits.

4. Using cover crops that winter kill

This means you plant a cover crop that you know will die over winter. Plant it early enough to grow and protect the soil and it dies with winter temperatures. No work involved in the termination!

5. Tilling the cover crop into the soil

Tilling a crop in is an organic method, even though deep tillage is destructive to the soil structure. Eliot Coleman uses this method proudly, he feels it has greatly improved his soil. It’s also an option to cultivate and till within the top 2-3 inches if you want to maintain more soil structure and microbial activity in the soil.

How to Know what Soil Needs

In order to fully understand how to use cover crops, and optimize them, you need very specific details. You can obtain the an in depth look of your soil through a soil test.

I highly recommend getting a soil nutrient analysis and texture analysis done by a professional laboratory. You can learn all about soil testing and my favorite testing service to use HERE.

Conclusion

I hope this has helped you understand better how to use cover crops in your garden. They are one of my most used “tools” in my garden to improve it.

Cover crops control pests, control diseases, attract beneficial insects, fix nitrogen in the soil naturally, suppress weeds, increase biodiversity, sequester carbon, increase beneficial microbes in the soil, reduce erosion, and add organic matter.

Their benefits are off the charts and it is worth the extra effort to grow them and add them to a crop rotation plan.