Growing vegetables year after year can reduce the productivity of the soil over time. The introduction of organic matter to the soil by adding compost or using cover crops is a great way for the home gardener to improve soil fertility, structure, and microbiome.
Utilizing cover crops in the home vegetable garden and other fallow garden areas takes special consideration.
Benefits | Types | Planning | Schedules | Establishment & Care | Termination | Seed Sources | More Informration
What is a Cover Crop?
A cover crop is a crop that is not intended for harvest and is managed to maintain and improve soil fertility, water quality, and help manage weeds, pests, and diseases. Cover crops can be planted in between vegetable crop plantings when the garden would otherwise be fallow, such as in fall after the last harvest. They can also be used as living mulch, growing at the same time as the vegetable crop in otherwise open soil areas, like in between rows or raised beds.
Benefits of Cover Crops
Cover crops have several benefits in the home vegetable garden, including improving soil structure, fertility, and compaction, suppressing weeds and pests, supporting wildlife, and integrating well into crop rotations.
Learn more in this article: Benefits of Cover Crops in Home Vegetable Gardens.
Types
Many different cover crop species have potential use in the home vegetable garden. Which you select depends on when you plan to seed, how long you wish to grow the cover crop, the growing conditions of the gardens, and your priorities or goals, such as providing weed impression, building soil fertility, or providing a living mulch, among other things.
Each cover crop species has its own attributes and can meet certain needs to different degrees. Learn more in this article: Types of Cover Crops for Use in Home Vegetable Gardens.
Cover Crop Mixtures
Cover crop mixtures are often more effective than planting a single species. Combining the benefits of grasses, broadleaves, legumes, and brassicas can help achieve optimal biomass and nitrogen production, as well as weed control. Seeding rates of species within mixtures must be adjusted to ensure adequate establishment and growth of the companion species.
Many seed sources provide cover crop mixtures blended at the right ratios to ensure adequate growth with instructions on appropriate seeding rates. Using these mixtures is the best place for the home gardener to start.
Examples of good cover crop mixtures include:
- Cereal rye and hairy vetch
- Cereal rye, hairy vetch, and oilseed radish
- Cereal rye and Austrian winter peas
- Oats and hairy vetch
- Oats and oilseed radish
- Sorghum-sudangrass and sunn hemp
- Buckwheat and sunn hemp
- Buckwheat and cowpea
Planning
To ensure gardeners get the greatest benefit from cover crops, proper planning and understanding of the factors to consider are important, so as not to interfere with the planting of your vegetable crops.
Termination
While termination is one of the last management steps in growing a cover crop, an exit strategy is one of the most important considerations. Cover crops that are not properly killed at the appropriate time can become significant and difficult weeds. Some species should be terminated before setting seed to prevent unwanted germination the following spring. The timing and method of termination must be considered.
For most home gardeners, utilizing a cover crop that winter kills is the best option. Cover crops that are killed by cold winter temperatures have the lowest risk of becoming weeds in the future and require the least amount of inputs to manage.
Purpose & Goals
Understanding your goals for cover crops helps you choose the best species for your needs. For soil building, choose high-biomass plants; for fertility, select nitrogen-fixing legumes; for weed control, pick fast-growing species with allelopathic properties. Each potential cover crop species addresses various benefits at different levels.
By understanding your priorities, you can select the best species for your situation.
Timeframe & Season
Vegetable gardens have fallow periods, such as after the fall harvest, before spring planting, or during the summer between spring and fall cool-season crops.
Some cover crop species thrive in cool weather, while others perform best in summer heat. Fast-growing species offer quick benefits, while others require more time to reach their full potential. Allelopathic species must be terminated 2-3 weeks before planting vegetables, and that time must be considered so vegetable crops can be planted at the right time.
Understanding the timing and duration of the cover crop helps you choose the right species for your garden.
Level of Care
Cover crops generally thrive in the same conditions that are ideal for vegetables - full sun and well-drained soils. However, they do differ in their tolerance to certain environmental conditions. For example, selecting drought-tolerant sorghum-sudangrass would be beneficial in dry conditions.
Cover crops also vary in the expertise and experience needed to grow them successfully. For new growers, selecting cover crops that have good germination rates, fast growth, and winter kill (making them easier to terminate) would be beneficial. Some species require specialized equipment for adequate termination. Experienced growers can select more challenging species if they have the right tools and knowledge.
Schedules
For most home gardeners, the best timeframe to utilize cover crops is in the fall after the last harvest, in summer between cool-season crops, or for an entire growing season to allow a garden area to rest and/or rejuvenate.
Fall
Planting cover crops after the last harvest in the fall is one of the best times for a home gardener to utilize and gain the most benefits from cover crops.
Planting can be from late August through early October (depending on the cover crop). Many recommended cover crops for home gardens winter-kill, terminating naturally over the winter. For crops that survive, they should be terminated 2-3 weeks before planting vegetables, typically between late March and late April.
Summer
In summer, garden spaces may sit fallow for 4-6 weeks between early season or short-term vegetable crops, like radish, and fall plantings of cool-season crops, like spinach. Fast-growing cover crops should be planted after the spring harvest (late June to early July) and terminated 2-3 weeks before fall planting, usually by mid-August.
Year-Long
If pests, disease, or fertility issues arise, rather than letting the garden bed simply sit fallow, planting a cover crop for the entire growing season is highly beneficial. This will help with crop rotation, breaking insect and disease life cycles, and building soil fertility.
Planting is done in early to mid-spring (April to May). Crops that winter kill are recommended for home gardeners and will terminate naturally over winter. For winter-surviving crops, termination should occur 2-3 weeks before planting vegetables the following spring.
Spring
Early spring cover crops can be weedy and hard to terminate for home gardeners.
The window of time for planting, germination, growth, and termination can be very short in the spring. There is a limited number of weeks between when cover crops can be sown and when vegetable crops are planted, especially cool-season crops. Additionally, residue from winter-killed fall cover crops can still provide benefits in early spring, such as weed suppression and erosion control. This makes the use of a spring cover crop less necessary.
For these reasons, the use of cover crops in the early spring before planting the vegetable garden is not recommended for home gardeners unless they are experienced with managing and terminating them.
Establishment & Care
Cover crops are direct-seeded in the garden. Before planting, prepare the soil bed to provide good seed-to-soil contact. This includes removing dead foliage and weeds and raking or tilling to give the soil surface a uniform texture free of large clods. Broadcast the seed by hand or with a spreader. After sowing the seed, lightly rake or drag the area. For most species, the seed should be covered to a depth of 1/8 to 1/4 inch. Raking also ensures good seed-to-soil contact.
After sowing, gently irrigate, keeping the upper inch of soil moist until the seeds germinate. Water when the soil is dry during germination, then water less frequently but deeper until seedlings reach 1-2 inches tall. Once established, water only during prolonged dry periods.
Most cover crops don’t require extra fertilization, but if soil fertility is low, a complete fertilizer (0.5 to 1 lb per 1,000 sq ft) can be incorporated before planting.
To prevent unwanted seed germination in subsequent growing seasons, cover crops should not be allowed to set seed. Terminate crops about a week after flowering starts, or mow the flowers off before or just after they bloom to avoid seed set. Mow just low enough to remove the flowers.
Termination
Proper termination is essential to receive all the benefits from cover crops. In general, cover crops should be terminated 2 to 3 weeks before planting the vegetable crop.
Many methods can be used by home gardeners, including winter kill, smothering, mowing, crimping, tilling, and herbicides. Learn more in this article: How to Terminate Cover Crops in the Vegetable Garden.
Seed Sources
Not all seed sources are well-suited for home gardeners, as they may sell in quantities much too large and are more appropriate for large-scale agricultural plantings. Several companies provide seeds and seed mixes for home gardeners. Potential mail-order/internet sources for cover crop seeds include:
- Green Cover Seeds
- High Mowing Organic
- Hudson Valley Seed
- Johnny’s Selected Seeds
- J.W. Jung Seed Co.
- Nichols Garden Nursery
- Park Seed Company
- Prairie Moon Nursery
- Renee's Garden
- Sow True Seed
- Territorial Seed Company
- True Leaf Market
No endorsement of companies is intended in this listing, nor is criticism implied of similar companies that are not shown.
More Information
- Benefits of Cover Crops in Home Vegetable Gardens
- Types of Cover Crops for Use in Home Vegetable Gardens
- How to Terminate Cover Crops in the Vegetable Garden
- Crop Rotation in the Vegetable Garden
- Managing Garden Soil
- Growing and Caring for Your Vegetable Garden
- Planning Your Vegetable Garden
- Midwest Cover Crops Field Guide (PDF)
Photo credits: 1: Vlad Varšavskij/AdobeStock; 2: Margaret Burlingham/AdobeStock; 3: AlienCat/AdobeStock; 4: Ajay Nair; 5: Enso/AdobeStock; 6: Sunny_Smile/AdobeStock; 7: Olga/AdobeStock