Various Cover Crops That Will Help Suppress Weeds In Your Garden

When planning a garden, one of the most important factors you need to consider is how you want to handle weeds. Hand-pulling the weeds can be a tedious task and not practical for larger gardens. Instead, it's best to plant a cover crop with weed-suppressing capabilities. These crops are able to naturally outcompete weeds, as well as smother any existing unwanted plants. Cover crops have a host of additional benefits as well, including preventing soil erosion, improving soil health, and attracting good insects.

There are a variety of cover crops to choose from, such as red clover, fava beans, buckwheat, and pearl millet. When selecting the best cover crop for your garden, you'll want to take into consideration how fast the crop grows, how dense its mat gets, which soil type you're working with, and the climate you live in. Planting season is also a factor, as certain crops are best suited to spring and summer planting, while others require fall or winter planting.

If you live in a U.S. Department of Agriculture Plant Hardiness Zone 7 or higher, areas that experience dry summers and wet winters, you'll find subterranean clovers are an excellent choice as a cover crop. They suppress weeds with thick mats that remain close to the ground and attract beneficial insects to the garden. Beneficial insects feast on pests, such as aphids, providing natural pest control and reducing the need for chemical insecticides. Subterranean clovers can also be used in areas that are prone to soil erosion, as they do an excellent job of holding the soil together.

Unlike buckwheat, which is recommended for summer planting, subterranean clover should be sown in the fall. Depending on the variety, you'll find it takes between 85 to 130 days to reach maturity. Trifolium subterraneum does best in acidic and neutral soils, while Trifolium yanninicum prefers wet soil. If your soil is alkaline, you'll want to go with Trifolium brachycalcycinum. While the crop isn't susceptible to disease, it is a favorite of livestock and deer. You'll need to choose a different cover crop if you have any hungry, roaming animals nearby that may be attracted by the clover, as they could inadvertently damage the other plants in your garden.

Rye is a cereal grain that is often chosen as a cover crop in areas that experience milder temperatures. It is known to prevent the growth of certain problematic weeds, such as foxtails, kochia, pigweeds, and marestail, as it produces a chemical that inhibits their growth. Since rye has a fibrous root system, it also competes to reduce other weeds in your home garden. This root system also helps protect against soil erosion.

The best time to plant rye as a ground cover is between September 15th and October 15th. The seeds only germinate when the ground is between 34 and 40 degrees Fahrenheit. The best practice is to broadcast the seeds over moist soil at a rate of 60 pounds per acre. Rye can survive in a variety of soil types as long as the pH falls between 4.5 and 8.0. The downside to using rye is that it doesn't offer complete weed control, so some herbicide later in the season may still be required. It's also susceptible to leaf rust, ergot, wheat streak mosaic virus, and the wheat curl mite. If you're using equipment to disperse the seeds, be aware that the seeds could shatter and clog up machine parts.

Michigan State University reports that red clover is the most popular choice when it comes to cover crops, and for good reason. The denseness of the crop provides excellent weed suppression. Red clover also draws beneficial insects to the garden, like bees, hummingbirds, and butterflies, while adding nitrogen to the soil. It even protects the soil against erosion.

Red clover can be grown in a variety of soil types, is winter hardy, and thrives in moderate climates. It does best with a soil pH between 6.0 and 7.2. Apply clover seeds at a broadcast rate of 10 to 15 pounds per acre, making sure that the seeds aren't planted any deeper than one-half inch to promote germination. Terminating the red clover in the spring can be accomplished by plow, eliminating the need to introduce chemical herbicides into your garden. A few pests and diseases to watch out for include clover root borers, meadow spittlebug, powdery mildew, and root rot.

Warning: Just like subterranean clover, red clover is delicious to cattle and deer and may attract them to your garden.

Suppressing weeds with their thick mats is just one of the many ways partridge pea cover crops benefit a garden. For example, the partridge pea presents delightful yellow flowers that capture the eye of important pollinators, including bees and three species of butterfly (sleepy orange, cloudless sulfur, and little orange sulfur butterfly). These flowers also produce seeds that feed game birds. Additionally, partridge peas mature quickly to provide soil erosion control and have roots that naturally decompose as the plants die out in the winter, adding more nutrients to the soil.

You'll want to plant partridge pea in the fall to enjoy blooms from March to August in soil with a pH no lower than 5.0. The cover crop does best in U.S. Department of Agriculture Plant Hardiness Zones 3 through 9 when planted in well-draining soils, such as sand or loam. When broadcasting seed, disperse 13.4 pounds per acre. Germination can take anywhere from 7 to 25 days. Partridge pea isn't bothered by disease; however, it is a food preference for deer and rabbits. Experts warn that the plant can be invasive, so keep that in mind when choosing your ground cover.

When it comes to using fava beans as a cover crop, the small-seeded varieties are best. The beans are able to compete with weeds, leaving less nutrients for the weeds to grow. While you can plant fava beans alone, they are often included with either rye or wheat. Fava beans provide the soil with lots of nitrogen, while wheat or rye offer added support to weather everything from wind to snow. Another benefit to using fava beans as a cover crop is their ability to add nutrients back into the soil as they decompose, reducing the number of fungal disease organisms to prevent infections.

Anytime between September and November is a good time to plant fava beans as a cover crop. Preferred soils include heavy silt, clay loams, and sandy soils that drain well (with an optimal pH between 6.5 and 9.0). Apply the seeds at a rate of 79 pounds per acre, making sure the seeds are at least 1 inch deep. Fava beans are reported to be susceptible to aphids and bean weevils, but only chocolate spot is listed as a known problem when it comes to diseases.

Fast-growing sorghum sudangrass is a hybrid annual grass that offers excellent weed control thanks to its high biomass. The plant's roots also secrete allelochemicals, which effectively kill specific weeds, such as large crabgrass, ragweed, smooth pigweed, and green foxtail. In addition to smothering weeds, this choice cover crop also helps prevent soil erosion, keeps the ground from becoming too compacted, and provides control of pesky nematodes.

Grown throughout the country, sorghum sudangrass thrives in soils with good drainage, such as clay, loam, or sand. Soil pH should fall between 6.0 and 8.0. Seeds should be broadcast at a rate of 40 pounds per acre at least 2 inches deep into the soil. You won't need to mow sorghum sudangrass if you plant it within seven weeks of a frost; however, if you sowed the seeds before this, you'll want to mow when the grass reaches a height of 4 feet. 

Warning: This cover crop can be toxic to some grazing animals, so make sure you opt for one of the other options mentioned here if you have cattle, horses, or passing deer that may munch on the plant.