what is a cover crop?

A cover crop is a crop that is planted on a farm or garden that meets the following qualifications:

• The cover crop is planted in a spot that would otherwise be dormant
• The cover crop replenishes the soil more than it takes from the soil
• The cover crop offers regenerative farmers a way to tend to their land in the off season

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our personal favorite winter cover crop

The past few winters, our greatest growing success was an edible crop that we didn’t plan on eating: daikon radish.

It’s not that we don’t like daikon (quite the contrary, the whole plant is delicious), but rather that we were growing this plant to feed the soil instead of us.

We had 3 new beds that we had built over former horse pasture, where the soil was dense, heavily compacted, and primarily clay. While we had good compost laid out over the land, which would provide a fertile surface layer, we wanted to go one step further and actually improve the land itself instead of just covering it up.

why are cover crops grown?

As a cover crop, daikon accomplishes a lot of different things:

• Soil softness: The radish part of the plant effectively breaks up compacted soil. Unlike some other root vegetables that might be stunted by hard ground, daikon doesn’t mind and persists through.
• Organic matter: When left behind into the growing season, the radish will break down and essentially compost in place. This further aerates and improves the soil.
  
• Conserve water: Soil aeration and improvement helps the soil to properly hold more water. Overtime this can mean that you need to water upcoming crops less during the heat of summer.
  
• Natural nutrients: The taproot can bring nitrogen up into the leafy greens of the plant. When these greens are cut down before going to seed and left to compost in place, they provide bioavailable nitrogen for the next crop.
  
• Shade out weeds: Daikon grows quite fast, and when planted densely can shade out weeds and prevent them from taking over an empty garden bed.
• Be lazy: Sowing daikon took very little work and it needed no tending in our Pacific Northwest winter/rainy season. We scattered the seeds on the surface by hand, and did little else but admire the pretty greens until early spring, when we put a tarp over the rows to allow the radishes to naturally break down into the soil. No watering was required, as the rain took care of that for us.
  
• Snacks for chickens! As a bonus, chickens love to eat the radish greens! Over the winter I would fill a pail with greens around 4-5 days a week to bring to the chickens as a snack. I would take individual leaves from various plants, avoiding pulling up the radish in its entirety. There was never really any sign of this harvesting via bare spots, and the chickens enjoyed the winter treat.
  
• Snacks for humans! Daikon is tasty! While we didn’t eat a ton of it as we were growing it to feed the soil, it did provide us with fresh greens through the early months of the winter, with the flavor of the radish added to our meals on occasion. This daikon pesto recipe, even without the basil, was a delicious delight.
  

Our daikon did so well outside that I decided to sow it inside our greenhouse, along with some winter crops like winter spinach, salad mix, chard, etc.

I alternated around 5 feet “soil food” daikon with around 3 feet of “human food” winter veggies. For example, I had a three foot wide sowing of winter salad mix nestled between 5 feet of daikon on either side.

One added benefit to the daikon that I didn’t expect was that it provided a “trap” for the slugs. Because it grew fast, it seemed like the slugs made themselves happy foraging on the daikon, and didn’t have a need to venture into my salad greens, spinach, or chard.

The only exception was some nibbling on a planting of bok choy, but I wonder if that was such a close relation to the daikon that the slugs went for it too.

While I did need to water the daikon in the greenhouse, I didn’t water it as frequently as I watered my “human food” crops.

why are cover crops important for the environment?

soil practices for a healthier planet

If you are gardening and have the ability to plant a cover crop, it’s an act that can actually support the planet - both through the soil and beyond the soil.

In fact, this study shows that if 20 million acres of farmland had a cover crop for one season that was properly cut back before the next growing season, it would offset the emissions from 12.8 million cars.

That’s 60 million metric tons of carbon dioxide! 1

For some context, the same would be accomplished if around 992,000,000 tree seedlings were grown for 10 years. 2

I did some research and found that currently, 4 billion acres of the planet are croplands.3

20 million acres out of 4 billion acres is just .5%.

.5% !

What’s happening here is the power of carbon capture.

You know that trees capture carbon dioxide and store it, sequestering it from the atmosphere.

Well, plants do the same thing - and in the case of cover crops, the carbon that is captured is stored in the soil.

If we planted 200 million acres of cover crops each year, napkin math says that would sequester the amount of carbon dioxide emitted by all passenger vehicles on a yearly basis4. That would be 5% of food croplands.

I understand that the science of all of this is more complicated than my napkin math, and so I might not be totally accurate here. But it’s promising nevertheless.

Other environmental benefits of cover crops are:

• Water less: as mentioned above, adding organic matter to the soil helps reduce the amount of watering that future crops sown in that same area need.
  
• Keep your soil: More organic matter means that the soil is less likely to wash away or erode.
  
• Attract pollinators: Many cover crops flower before going to seed. By allowing the plants to flower and then cutting them back before they go to seed, farmers can provide food for bees and other pollinators. 5
  
• Less slugs! Less aphids! Cover crops also attract beneficial insects that eat garden pests (or their eggs) while leaving your plants alone. Slugs are the bane of my existence, but cover crops attract beetles which feed on slug eggs. The cover crops don’t even need to flower to provide habitat for these amazing creatures. 6 For some farmers, this may mean less pesticides are applied.
  
• Buy less fertilizer: If you’re planting a cover crop that provides nutrients to the soil, you probably will need less/little fertilizer the following season. This prevents excess nitrogen and other fertilizers from running off and going into waterways. 7
  
• Less pesky plants: If farmers don’t have a weed problem because the cover crop solved that, then herbicides aren’t needed. 8

plus…

• Bonus points! Planting a cover crop and improving the soil may mean that you don’t have to till. No-till practices further reduce the amount of carbon and methane released from the soil. 9
  

“Conventional tilling, that is plowing up the dirt, encourages microbial action. That can lead to CO2 emissions and the more potent greenhouse gases methane and nitrous oxide.” 10

Cover crops benefit the environment and your garden in a huge way

you can help spread the environmental benefits of cover crops

Don’t have a garden? Here’s what you can do:

If you have a yard with grass, consider planting clover with the grass to increase your yard’s carbon sink.

If you live in an apartment and have access to a farmers’ market, try to obtain your weekly produce there instead of at big markets. It’s likely that these small farmers utilize a cover cropping system of some kind - strike up a conversation and ask them about it!

Have a small-medium garden? Cover crops for a garden of any size, and cover crops work in raised beds!

Think about what would benefit the soil and your upcoming vegetables. Here’s a handy chart. If you’re like me and have compacted soil, daikon may be helpful. But, daikon is part of the cruciferous vegetable family, so any pests attracted by the daikon may stick around and then go for any other vegetables of the same group. If you grow 80% broccoli and other cruciferous vegetables, you might want to pick a different cover crop.

Are you a homesteader or big time farmer? Here’s what you can do:

Did you know that there are grants and other programs for funding to help mitigate the costs of planting a cover crop? Did you also know that planting a cover crop can help reduce your overall costs? Reach out to your local extension office to learn what’s available for you.

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Which cover crop should you sow?

Before you go, read our guide that will help you decide which cover crop to sow, depending on your needs, time of year, and other factors.

Want to learn all of the pracitces to build soil fertility?

Check out our soil health guide full of regenerative practices to boost your garden while supporting the environment