Raised bed gardening is a fantastic way to grow food. However, like any garden it needs some care and maintenance. One of the best ways to keep your raised bed healthy and fertile is by planting cover crops in the winter.
What are Cover Crops?
Cover crops are plants that protect the soil from erosion, help prevent weeds from growing in your gardens, improve soil fertility, and provide nutrients for other plants in your garden.
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They don’t have to be grown with the intention of harvesting for food. In fact, many cover crops can simply be worked back into the soil when you’re ready.
Cover crops can also be grown and harvested as a green manure, which is when you cut the plants down before they set seed. You can drop the harvested portion on top of your soil to let it break down or add it to the compost pile. (Learn how to compost here!)
The Benefits of Cover Crops
No one wants extra work, so what benefits do cover crops provide for raised beds (and traditional row gardens)?
- Breaks up compacted soil : They loosen up compacted soil so you don’t have to work it in when planting your next crop
- Add Organic Matter to Soil: Cover crops add organic matter and nutrients to the soil as they grow. So you may not need to amend your raised bed’s soil as much come spring, which saves money! Plus, you can add some of your green manure to your home compost pile.
- Suppress Weeds : Cover crops compete with the weeds, so you don’t have to worry about them taking over a bed that is otherwise unused.
- Reduces soil erosion: If cover crops are not harvested, they protect your raised beds from wind and rain erosion which can be a big problem in some climates.
- Great for your Garden: Cover crops are beneficial to any garden, including raised beds because it allows you to grow a crop in winter, when you may not usually have made the effort, all while building up your soil for the next spring.
- Nitrogen Fixing– Some cover crops can provide valuable nitrogen to your garden soil. See this article from Michigan State University for more information!
When to Plant Cover Crops
When choosing a cover crop, consider the time of year and what you will be planting in your garden. While I prefer to use cover crops in the fall and winter, they can still be grown other times of year as well.
If you plan to grow vegetables along with cover crops, make sure they won’t interfere with each other or compete too much for nutrients. You can even mix certain plants together like oats and rye if it works well for both of their growth.
For winter cover crops, plant after the fall harvest but before winter sets in. You want seeds to have the opportunity to germinate.
For summer cover crops, plant them mid-spring for an established summer presence.
Summer Cover Crops
If you are planning on planting cover crops in raised beds in the spring to turn in summer, choose cover crops that will grow quickly and produce a lot of biomass to keep your soil covered or mulched best. There are many great options for summer covers but some include
- buckwheat
- crimson clover
- alfalfa
- cowpeas (I love to grow these for a harvest as well!)
- garden peas
Winter Cover Crops
If you are planning on planting cover crops in the winter, choose cover crops that will grow quickly but also survive cold weather or can handle being covered with snow or ice at times. Some great options include
- rye
- oats
- cereal grains like winter wheat
- garden peas
- radishes
I also enjoy planting collards, turnip greens, and mustard greens as both a harvest crop for eating in the winter and a cover crop. Simply plant more than you need and harvest some, while cutting the others for green manure.
How to Turn in Cover Crops
When should you turn in your cover crops? The best time to turn in the cover crop is when they are green and still coming up. You want to avoid waiting until your crop is flowering or going to seed.
In a raised bed, there’s no need for tilling. Simply cut down the part of the plant above ground, and leave the roots in place. Another option is to turn over the crop into the soil, trying not to disturb the soil too much.
The green manure from cover crops also encourages beneficial insects and pollinators while the plants are still growing. Then it has a variety of uses once it’s been cut!
What can I do with a green manure? You can dig them into the soil before they go to seed, or you could simply let them decompose on top of your bed as mulch. There’s no wrong way! As I mentioned before, you can also add to a compost pile if there’s no sign of pest damage or disease.
Cover Crop FAQ’s
- Are cover crops worth it? Yes! Building up soil is crucial to a garden’s success, whether a traditional row garden or a raised bed garden. See my guide for Improving Garden Soil here.
- What is the cheapest cover crop? At this time, rye or oats appear to be the cheapest, but always keep in mind that planting raised beds with a cover crop uses significantly less seed, so grow what you prefer.
- I want great tomatoes next summer, what winter cover crop should I use? Oats are a great choice for a bed that will hold tomatoes next year.
I’d love to know how using a cover crop in your garden has improved the soil, or if you have used something else as a cover crop. Have a great week and happy gardening!
