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The Best Cover Crops For Raised Beds

When you think of cover crops, large-scale farms or gigantic in-ground vegetable beds may come to mind. But, did you know you can just as easily plant cover crops in your raised beds?

Cover crops for raised bed

There are many reasons you may want to plant cover crops in your raised beds or home vegetable garden. Bare soil is susceptible to the harsh elements and overgrowth of weeds. Cover crops help to protect your soil while also improving soil fertility and structure.

Tip: I recommend choosing a cover crop blend. This will ensure a balanced mix of crops that serve multiple functions. There are many pre-made blends available for purchase depending on the time of year you are sowing the seeds.

The varieties of crop listed below are typically included in blends, and it is important to know the function of each crop in the garden and how it contributes to your soil’s health.

What are cover crops?

Also known as “green manures,” cover crops are planted to cover the soil in your garden and help increase soil fertility. Unlike vegetables in the garden, cover crops are not grown to be harvested and eaten. Instead, they are grown to help improve the quality of your soil.

I’ll discuss the many benefits of growing cover crops below. There are many different varieties to choose from, and plenty of cover crop options suitable for your raised beds.

What are the benefits of using cover crops in your raised bed?

  • Soil health – Cover crops help to improve soil quality and structure. The roots help to break up compacted garden soil and provide a favorable environment for soil organisms.
  • Nutrients – Some cover crops, especially legumes, have the ability to fix nitrogen in the soil. This makes it available for future crops to use in your raised bed.
  • Weed management – Not only do cover crops help with soil fertility, but as an added bonus, they help control weeds. Cover crops can outcompete weeds, reducing the need for manual weeding.
  • Erosion control – The roots of cover crops helps to keep soil in place. This helps prevent erosion that is caused by rainfall.
  • Soil moisture – Cover crops can help to retain soil moisture. This is useful in raised beds which tend to dry out faster than in-ground garden beds.
  • Organic matter – When cover crops are cut down and left to decompose, they add nutritious organic matter to the soil. This matter feeds soil microbes and earthworms, and helps to improve soil fertility and structure.
  • Beneficial insects – Cover crops that flower can attract pollinators and beneficial insects to the garden.

Different types of cover crops

Oats in a field

There are many varieties of cover crop seeds you can choose from. If you are unsure which is best, it is easy enough to purchase a cover crop mix for your garden. This will be a blended mix of different seeds, taking the guesswork out of which cover crop to choose. These are also known as cover crop blends and can be purchased here.

  • Legumes – These cover crops are best known as “nitrogen-fixers.” They are great for increasing the nitrogen level in soil. Examples include clovers, field peas, and beans.
  • Grasses and grains – Grasses have robust root systems, which help improve soil structure and organic matter. They also help prevent erosion and suppress weeds with their dense growth. Examples include oats, wheat, and rye.
  • Broadleaf – These cover crops help with weed suppression while also helping to provide valuable organic matter to the soil. Some cover crops in the Brassicaceae family can help with soil compaction due to their deep taproots (like daikon radish). Other examples include mustards, buckwheat, and turnips.

When to plant cover crops in raised beds

The end of the summer growing season is the best time to plant your cover crops. In late summer or early fall, weed your raised garden bed and remove any spent plants. Seed your raised bed with the cover crop of choice. Then water, set it and forget it! The cover crops will grow, and come early spring, you can cut them back and begin planting your vegetable garden.

Winter hardy vs. non-hardy cover crops: With the goal of building fertility in your raised garden bed, you should choose cover crops that are annuals. These cover crops can be hardy to below freezing temperatures, but will die back, making them easier to manage.

Best cover crops to grow in your raised bed

1. Buckwheat

Buckwheat flowers

Buckwheat grows very quickly and also breaks down fast, making it a good choice for a cover crop in your raised bed. It can reach flowering stage in as little as 4-6 weeks. You can sow buckwheat between main crop plantings, or plant it during gaps in your growing season. The dense root structure helps to break down compacted soil, improving structure and aeration.

The flowers are also attractive to beneficial insects in the garden, helping to control pest populations. This cover crop also has soft stems, making it easy to cut back.

Sow seeds directly into your raised beds in the late summer. It will grow rapidly, helping to keep the soil covered and active before dying back in the cool temperatures. You can also direct sow it in spring or summer after the danger of the last frost has passed, as it is sensitive to cold temperatures and frost.

2. Clover

Crimson clovers

Clover falls under the “legume” category of cover crops, making it popular for it’s nitrogen-fixing ability. There are different varieties of clover to choose from. Crimson clover produces attractive flowers that also attract beneficial insects to the garden.

After the flowers bloom, cut the clover back to the ground and compost the foliage. White clover is more expensive to purchase, but tolerates shadier conditions and more acidic soil.

3. Oats

Oats

Oats are a cool season annual crop and have been used as a cover crop in gardening and farming for decades. They’re easy to grow, fast-growing, and affordable. Unlike ryes, they are winter-kill in zones 6 and colder, making it easy to manage in the spring.

Oats are often used in cover crop blends with peas or other legumes and are excellent at preventing erosion, scavenging nutrients, and providing biomass.

4. Radish

Daikon radish in garden

Radish is a cool season cover crop that grows relatively quickly. When shopping for radish to use as a cover crop, you may see it listed as “Oilseed radish” or “Forage radish/Daikon.” These two varieties are similar and both can be used as a cover crop.

The large taproots can help penetrate through layers of compacted soil. It establishes quickly and can be mixed with other cover crops like legumes. Radish is also cold hardy, but winter kills, making it a good option for fall planting. This is a good article all about using radish as a cover crop.

5. Hairy vetch

Hairy vetch

Hair vetch is a sprawling vine that provides large amounts of nitrogen to the soil. It is also a great option for improving soil tilth and competing with weed growth.

It’s very popular in cover crop blends, especially mixed with clover and cereal grains. For a raised bed, I would recommend a blend with oats as opposed to rye (for easier spring management).

6. Peas

Peas growing in the garden

Field peas, also known as Austrian winter pea, black peas and spring peas, are another good choice for cover cropping. They are high nitrogen fixers which also help with weed control due to their rapid growth. You’ll often see them mixed with oats in cover crop blends.

Other cover crops

Winter wheat and winter rye are inexpensive cover crops that can be used in your raised bed. However, I would not recommend them as much as some of the options above.

  • Winter rye: This cover crop is winter hardy and is best planted in the late summer or fall. It is important to keep in mind that winter rye produces a very large root system. It will also survive the cold winters, providing a green cover to your raised beds while other crops have died back. This cover crop is more vigorous than others, making it more of a challenge to terminate. Rye can also inhibit the germination and growth of subsequent crops in the garden. Therefore, full decomposition is recommended before planting sensitive crops.
  • Winter wheat: Winter wheat is less winter hardy and is easier to manage than winter rye in the spring. It is a good cover crop for erosion control and weed suppression. When sown in fall, winter wheat will grow quickly and then go dormant in the winter. When it begins to grow again in the spring, it can be turned into the soil.

When and how to cut back cover crops in the raised bed

The timing and method of cutting back or terminating your cover crop will depend on the type of cover crop you grew, and the upcoming plans in your garden.

Generally, you’ll want to cut back your cover crops before they flower and seed. This ensures the cover crop does not become a weed problem and that the nutrients are available for the following crop.

For winter cover crops, cut-back is usually best done in the spring. You’ll want to cut them back a few weeks before spring planting the main crops in your garden. This allows the cover crop time to decompose.

For small raised beds, use garden shears or a weed trimmer to cut the cover crops down to the surface of the soil. You can leave the cuttings on the surface as mulch, compost them, or incorporate them into the top layer of the soil to decompose. If you choose to turn or dig the crop residue into the soil, it is important this process is done a few weeks before planting your crop.

Tip: for faster decomposition, cut off the foliage of your cover crops and use them in your compost. Then, turn only the roots into the soil for quicker breakdown.

If you don’t have the time or energy to plant cover crops in your raised bed, consider mulching your beds instead. An organic mulch will cover and protect the soil while also adding organic matter and helping to improve the fertility of your soil. Learn how to make leaf mulch here.

​When deciding which cover crops to grow in your raised bed, I suggest seeding multiple varieties and seeing which crops thrive. Experiment with different blends and see what works best in your zone and for your gardening needs.

– Crystalyn

Always looking for new ways to get creative in the garden, Crystalyn enjoys getting her hands dirty with vegetables, flowers, and tropical plants. In the off-season, you’ll find her moving the hobby indoors with her vast houseplant collection.

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