Top 3 Reasons You Should Grow Cover Crops for Raised Beds

October 22, 2023

Perhaps you have heard of cover crops before, but only thought they were important for farmers or large scale gardens. Well, I’m here to tell you that cover crops for raised beds are an incredible addition to your gardening practice! Not only do they improve your soil health, but they also suppress weeds, add in beneficial nutrients, decrease soil compaction, and attract beneficial insects! I am a huge fan of cover crops and think every gardener should incorporate them into their garden. Let’s deep dive into a few of the benefits and then talk about how you can start planting cover crops in your garden beds!

cover crops for raised beds

Benefits of cover crops for raised beds

1) Increases organic matter

One of the prime benefits of cover crops for raised beds is the increase in organic matter. Why does this matter? Well, organic matter increases our soil quality. And if you want a bountiful garden, you need high quality soil.

Soil is literally and figuratively the foundation of our garden. Soil is a mixture of weathered rock fragments (such as sand, clay and silt) and organic matter. Organic matter is quite literally the glue to our soil! It can improve any type of soil – from hard compacted clay soils and fine-textured sandy soils. 

Organic matter is quite simply plant or animal matter that decomposes in our soil. This can include food scraps, grass clippings, leaves, animal manure and worm castings. If this is sounding similar to the ingredients of compost, then you are on the right track!

If you are like me, you are probably adding bags and bags of compost to your garden every year to refresh your soil. And while compost is a great way to do that, cover crops are an excellent addition!

It might be helpful to think about our soil as a bank account when it comes to organic matter. In order to make withdrawals (to grow and harvest our plants), we must make deposits in the form of organic matter. The deposits of organic matter will not only provide nutrients to plants, but also help feed microorganisms that are vital to our soil health. And cover crops are an excellent form of organic matter, both while growing the cover crop, as well as using it as a mulch! Which brings me to the next benefit…

2) Can be used as a mulch to suppress weeds

Soil does not like to be bare. Therefore, your garden beds should always either have plants growing in it or some form of mulch covering it (and sometimes both!). Weeds seeds are incredibly advantageous and will travel far and wide to find bare soil to take root. Though some weeds are inevitable, there are measures we can take to suppress them!

buckwheat


Cover crops for raised beds can suppress weeds in a variety of ways:

Competition

By filling our garden beds with cover crops, it will be directly competing with weeds for light, space, nutrients and water. This will help reduce the chances of those weed seeds germinating and spreading!

Allelopathy

Allelopathy is when one plant inhibits the growth of another plant through the release of a chemical inhibitor. This can occur while the cover crop is growing and even after it has been tilled into the soil. This is a great way to reduce the chances of weed seeds from germinating. Though, it can also potentially inhibit the growth of your vegetable plants. The effects will wear off as the cover crop breaks down in the soil, so it is important to be aware and plan ahead!

Mulch

After your cover crop has grown, and right before it goes to seed, you can “chop and drop” directly onto your soil. The plant matter will serve as a mulch, blocking light from reaching the soil, and reducing weed seed germination. A double bonus – as it breaks down, it will provide organic matter to your soil (remember that from earlier?). If you want a long lasting mulch, then you should consider grass cover crops, which will break down slower than the nitrogen-rich legume cover crops.

3) Improve soil fertility

Nitrogen is one of three important macro nutrients that helps our plants grow (the other two being phosphorus and potassium). Plants need nitrogen to help with rapid growth before they grow their fruit. Our soil is often lacking in nitrogen either because of heavy feeders that depleted the soil, or because of rain and irrigation that washed it away. If nitrogen isn’t being used by plants, then it has an increased chance of leaching from the soil.

We often find ourselves adding nitrogen to our soil every year – sometimes multiple times throughout the year in the form of compost and fertilizers. While this works, there is another way that requires less work! Certain cover crops are nitrogen fixers, which means they are able to take nitrogen from the air and convert it to nitrogen in our soil that can be made available for our plants. This is absolutely amazing!

The cover crops that are able to do this are legumes, which include red clover, sweet clover, garden pea, winter pea and hairy vetch.

How to plant cover crops

It can be a difficult decision to give your garden bed a break to grow cover crops. We don’t want to sacrifice the precious amount of growing days in our garden! There are a couple of different ways you can plant cover crops for raised beds to have the best of both worlds.


1) Add cover crops into your crop rotation

Ideally, we are following some sort of a crop rotation in our garden, whether that be for the entire garden bed, or by section. Crop rotation is the practice of rotating crops with different nutrient needs to increase soil health and decrease issues, such as diseases or pests. This can be challenging in a small garden bed, but can be achieved if you divide your garden bed up by quadrants. Crop rotation can sound complex and overwhelming, but quite simply it is leaf → fruit → root → legume. 

Using this rotation can help you determine which cover crop would be more helpful! Did you just harvest a bed full of carrots and radishes? Plant a legume cover crop such as winter pea or crimson clover. Did you just harvest a bed full of peas? A grain is an excellent choice, as it will pull the nitrogen up to the surface of the soil, as well as become nitrogen-rich organic matter after you chop and drop it as a mulch.

Crop rotation

2) Interplanting

I am a huge fan of interplanting in a small garden space. Interplanting not only allows us to grow a variety of vegetables, it also helps support the health of our garden! By interplanting cover crops with our vegetables, they will only add important nutrients to the soil, but also act as a living mulch!

You do have to be mindful of which cover crop to choose to interplant with your vegetable. For example, you do not want to grow an allelopathic cover crop that will inhibit the growth of your vegetable, or one that will otherwise compete for nutrients. You also do not want a cover crop that will grow taller than your vegetable.

Low growing legume cover crops, such as hairy vetch or crimson clover are particularly good options for heavy feeder vegetables such as corn, pumpkins and brassicas. The best method here is to direct sow your cover crop after your vegetables are established in your garden. This will minimize the competition for sunlight, water and nutrients. If you are planning on interplanting with your fall garden, you might want to check out this blog post to help with your planning.

Where to get cover crops for raised beds

Once you have decided which cover crop you want to plant, the next step is finding it! The first place I always check is my local nursery. They often have an excellent selection of cover crops that do well in our particular zone. You can also find cover crops online from seed companies including Johnny’s Selected Seeds, Territorial Seed Company, and Hudson Valley Seed Company. Cover crops usually come in a large bag, so it will last you many seasons!

As you are planning your kitchen garden throughout the seasons, I hope you find the opportunity to experiment with cover crops! Whether you plant and entire bed or intercrop with your vegetables – your soil will thank you! And if you are in need of inspiration in your garden planning, make sure to check out the Kitchen Garden Seasonal Planning Guide.

This free 24-page guide provides sample garden plans for each season, seasonal garden tasks, space for you to plan your own garden beds, a BONUS Weekly Garden Log, and more. If you want to try out the Seasonal Planning Guide for your fall kitchen garden, you can download it below!

Happy gardening!

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