Using Winter Cover Crop to Build Soil in Your Garden

Did you know that sowing winter cover crop can give you a better Spring garden? Keep reading for all the details on using winter cover crop to build soil in your vegetable gardens.

Potential Benefits of Winter Cover Crop

There are a few different reasons why a gardener might consider sowing winter cover crop seeds in his or her garden.

1. Adding Organic Matter
2. Retains Water
3. Weed Suppression
4. Builds Soil Structure

1. Organic Matter

First and foremost, winter cover crops can help build a healthier soil by adding organic matter into your growing spaces. 

You may have heard the term “green manure.” This has zero to do with manure and everything to do with being green. Winter cover crop adds green biomatter right into your garden.

Like manure, winter cover crop is sown directly into the garden for the purpose of adding fertility, working towards nitrogen fixation.

​2. Water Retention​

Next, acting as a mulch, winter cover crop creates a natural water retention in your garden. Retaining moisture is an essential part of soil health because where’s there’s water, there’s life. 

Think about that on the microscopic scale. We need moisture for all of those tiny biological relationships to work within our soil. As the cover crop seed grows, the plants will cover the soil to prevent evaporation.

As the soil is watered, the moisture will stay in the root zone better instead of draining right through.

3. Natural Mulch For Weed Control

Third, winter cover crop works as a natural ground cover to keep weeds at bay. Remember that soil needs to be covered or else there’s too much opportunity for weed pressure to take over your growing space. 

Keeping the soil from remaining exposed will help prevent wild weed seeds from sprouting and competing for nutrients with your vegetables. Less weeding means more time planting, harvesting, and enjoying your garden.

4. Improve Soil Structure​

Lastly, using a winter cover crop will help build structure within your soil. The fibrous roots of the cover crop will create pores to reduce soil compaction in the top layer of soil, which helps water permeate deeper into the garden beds.

Cover crops will also add literal mass to your garden beds. Have you ever noticed that as the growing season progresses, you seem to lose soil? Let’s work to replace it naturally, closing the loop on your homestead to increase sustainability.

Further, using a cover crop will certainly help to prevent erosion if that’s a problem in your garden space. The crop will create a mat of sorts, holding the soil beneath in place.

Cold Weather Cover Crops

Remember that we’re talking about the cold season. That means that we should select seeds for plants that can withstand our coldest expected temperatures.

​Choosing the right kind of winter cover crop will help you succeed in your mission to better your garden soil. Additionally, realize that if you still get warm temperatures in winter, like we do here in North Florida, too much heat may cause your crop to go to seed or die back.

Types of Cover Crops

​Winter cover crop can be easily divided into three types:

• Brassicas
• Grains / Grasses
• Legumes

​Let’s dive deeper at each type of these cover crops to help you choose which is right for your garden.

​Brassicas

Some brassicas have larger roots, such as turnips, that can really help break up soil. This is a great option if you have rocky or clay soil.

Others, mustards for example, are fast growing, helping you cover bare soil quickly. Mustard is a good choice if you have a nematode problem too because they release a natural chemical that kills root knot nematodes. Don’t worry, they aren’t toxic to us.

You might consider using brassicas as a winter cover crop because they take up less nitrogen than other crops. This leaves nitrogen in the soil for the vegetables that you plan to grow later.

Using brassica plants as a winter cover crop is becoming increasingly popular amongst tuber crop growers, specifically potatoes. Not only do farmers see a reduction in pest pressure, they see a reduction in disease.

Lastly, brassicas typically die back quickly when the weather warms. A quick die off means earlier planting of the vegetable you hope to eventually harvest.

List of Brassicas​

​Think past cole crops when it comes to brassicas. Sure, you’ll have your kales and broccoli, but I’d prefer to harvest those as vegetables to feed my family. Check out this list of brassicas that you can use a winter cover crop:

1. Broccoli Rabe (Brassica rapa)
2. Brown Mustard (Brassica juncea)
3. Daikon Radish (Raphanus sativus var. longipinnatus)
4. Forage Rape (Brassica napus)
5. Kale (Brassica oleracea)
6. Oilseed Radish (Raphanus sativus)
7. Turnip (Brassica rapa)
8. White Mustard (Sinapis alba)

Grains and Grasses as Winter Cover Crop

​You might choose to use small grains or some grass seeds as your winter cover crop for a few reasons.

Firstly, they grow incredibly fast. Winter rye grass seed can sprout in as little as five to seven days, given the right conditions. Simply throw the seed down, rake it into the soil, and keep it watered. You’ll be amazed at how quickly you just became a grass farmer for the season.

Next, grains like winter wheat and cereal rye are usually easy to find in your local farm stores. No special ordering required makes this an attractive choice.

Last, grains and grasses might have secondary uses for your homestead. If you have a large growing space, you could use grains as a cash crop; although, it takes a lot of space to grow enough grain to sell. 

Alternatively, cutting and feeding to your animals is a great way to use the grains that you’re growing as cover crop. To make this an easier option, consider just letting the animals into your garden space to mow it down for you before you plant your spring garden.

List of Grains and Grasses as Winter Cover Crop

1. Annual Winter Ryegrass (Lolium multiflorum)
2. Barley (Hordeum vulgare)
3. Cereal Rye (Secale cereale)
4. Oats (Avena sativa)
5. Triticale (× Triticosecale)
6. Wheat (Triticum aestivum).
7. Lupine (Lupinus luteus)

Legumes for Winter Cover Crop

Legumes capture atmospheric nitrogen and convert it into a form usable by plants. This natural nitrogen source reduces the need for synthetic fertilizers in the following season. They do this through a symbiotic relationship with rhizobia bacteria in their root nodules, and this leaves the soil more nitrogen rich.

Dense legume cover crops help to smother weeds by outcompeting them for light, nutrients, and space, reducing weed pressure in spring.

These benefits make legumes valuable for maintaining soil health and boosting productivity in crop rotations.

List of Legumes of Winter Cover Crop

​Check out this list of legumes you can use as a cover crop in your garden during winter:

• Crimson Clover (Trifolium incarnatum)
• Hairy Vetch (Vicia villosa)
• Field Pea (Pisum sativum)
• Winter Pea (Pisum sativum subsp. arvense)
• Berseem Clover (Trifolium alexandrinum)
• Red Clover (Trifolium pratense)
• White Clover (Trifolium repens)
• Sainfoin (Onobrychis viciifolia)
• Soybeans (Glycine max) (early maturing varieties can be used as a cover crop in some regions)
• Faba Bean (Vicia faba)

Winter Cover Crop Mix

We, Jenny and I, constantly talk about diversity in the garden. Whether you’re making compost or layering soil components, we need diversity to create balance in our gardens.

Companion planting is a great way to add biodiversity into your garden, so I highly recommend using a mix of winter cover crop seed. This will increase microbial activity and encourage beneficial organisms in the soil, supporting a balanced ecosystem that can reduce pest and disease pressure for future crops.

Timing is a little more important when you use a mix. You don’t want your fast growing brassica to shade out your slower growing legume. You’ll need to plant the slower or shorter plants first, giving them a jumpstart ahead of the larger, faster plants.

The best way to figure this out is to talk to your local extension agent. Let them tell you what mix will work best in your area. They may suggest a soil sample first so that you know what’s lacking, and what you might plant to boost your soil fertility.

When to Plant Winter Cover Crop

The best time for planting cover crops can vary based on the specific crop, climate, and the intended benefits. Here are general guidelines for when to plant cover crops.

Plant cover crops after the last harvest of summer crops, typically in late summer to early fall. For most regions, aim to plant 4-6 weeks before the first expected frost. This gives the cover crop enough time to establish before winter. 

In warmer areas (like USDA Zone 8b), you may have a longer window, allowing for planting until late fall. 

I personally love living in the South for this reason. Our winter growing season is pretty forgiving. When it comes to cover crops, just sow them in. You can’t really get the timing wrong. 

If they die too early, just cover it over until you’re ready to plant the spring garden. If they live too long, you can till it in before planting, or cover it for a good two weeks before planting.

How Do You Sow a Cover Crop?

Take these steps to easily sow your winter cover crop.

1. Select a cover crop that suits your soil type, climate, and goals (e.g., improving soil fertility, suppressing weeds, enhancing biodiversity).
2. Prepare the seedbed by tilling the soil, if necessary, to break up compaction and improve seed-to-soil contact. However, conservation tillage methods can also be effective.
3. Sow your seeds by using one of these methods:
   • Broadcasting: Spread seeds evenly over the soil surface by hand or using a broadcast spreader. This method is suitable for small areas.
   • Drilling: Use a seed drill to plant seeds at the recommended depth and spacing. This method is more precise and can improve seed-to-soil contact. This isn’t feasible on a small scale, and special equipment is needed.
   • No-Till Planting: In no-till systems, seeds can be drilled directly into the undisturbed soil or residue of previous crops.
4. Watering to ensure adequate moisture for seed germination, especially if rainfall is insufficient after sowing.
5. Mulching. If desired, use straw or other organic mulch to help retain moisture and suppress weeds. This is especially beneficial when sowing grass and grain seeds.

What Happens with Cover Crops in the Spring?

You did it. You successfully used a winter cover crop, but now what? Now, you have a couple of different options to terminate your cover crop.

First, you can let cold weather loving crops just die back with the heat. This would work an the scenario of using winter rye and then planting tomato transplants. Just dig a hole in the rye grass where you want to plant your seedling. Take out enough grass (if it’s still alive) to keep it from smothering your tomato plants.

Secondly, you can chop and drop. Mow the crop and leave it where it lies, allowing the plant to decompose in place. Again, pull back the chopped crop material to plant your spring plants.

Thirdly, till in the cover crop. If you do this, I recommend you cover it over with a tarp for at least two weeks, four weeks is better, to let kill back any seeds that were exposed by tilling. You need to plan ahead and handle this before early spring arrives.

Last, you could use an herbicide, BUT I DON’T RECOMMEND IT. Large scale row croppers use this method, but I strongly feel it is unnecessary to expose your new plants to possible herbicide damage. 

Are There Summer Cover Crops?

Absolutely. You can use summer cover crops to attain the same results as winter cover cropping. However, you’ll need to use different plants that like the heat. 

​​Summer cover crops are typically planted after the last frost in spring and before the first frost in fall. Plant them after harvesting spring crops or early summer. Aim for a planting window of late spring to early summer, allowing the cover crops to establish and grow throughout the warmer months.

You can use grasses/grains and legumes for summer cover crops, but brassicas will simply bolt, flower, and die quickly (maybe even before they grow).

Select cover crops based on your goals and local conditions. Here are some common summer cover crops:

1. Buckwheat (Fagopyrum esculentum): Grows quickly, suppresses weeds, and attracts pollinators. Best planted in late spring.
2. Cowpeas (Vigna unguiculata): A drought-tolerant legume that improves soil nitrogen and is well-suited for hot climates.
3. Sunn Hemp (Crotalaria juncea): A fast-growing legume that adds nitrogen and organic matter; best in warm areas.
4. Millet (Pennisetum glaucum): A warm-season grass that helps improve soil structure and control erosion.
5. Sorghum-Sudangrass (Sorghum bicolor): A robust grass that produces a lot of biomass, improving soil organic matter and suppressing weeds.

You’re Covered For Winter

Using cover crops will help suppress weeds, retain moisture, reduce soil compaction, and improve soil health through nutrient recycling and organic matter addition. I sincerely hope that you’re encouraged to try using a winter cover crop this year in your vegetable garden. Please report back to us to let us know how it went.

Happy Cover Cropping!

Donna and her family have been homesteading for most of their 20+  years together in some shape or fashion. She currently lives on their 20 acre farm where they grow as much food as possible. What started as a just a few laying hens, has grown into large gardens, pastured poultry, pork, and lamb. They are continuously evolving their small farm to not suit their family’s needs, but also providing to their local community. Donna’s favorite part of the family farm is her self-built micro-dairy, where she gets to love on dairy cows while serving her local community. Milking, cheesemaking, and processing dairy have become the soul of their homestead and the center of their farm.