What “cover crops” could home gardeners consider in the fall?

Farmers across the country use “cover crops” over the winter. Cover crops do several things, depending on what is planted:

1. Help prevent erosion and topsoil loss. Their roots, and the plants themselves, help hold the soil in place during wind, rain and other weather events.
2. Provide organic matter to the soil the following spring. These “residues” can be gently tilled into the soil in the spring during planting. The organic matter provides essential nutrients for the newly seeded vegetable crop. This addition of organic matter upon decomposition also improves soil structure. It increases the ability of soil to soak up water, and make water available to roots. Good soil structure also improves oxygen availability for plants and allows better root growth, and.
3. Break up soil compaction through “bio-tilling” processes done by roots. Some cover crops, such as nitro radishes, are grown specifically for these bio-tilling effects.

Bil, a CCA agronomist from Easton, MN, visits a recently harvest field to check on cover crop (tillage radish) progression. Credit: William Schrader

Home gardeners and landscapers can use cover crops, often referred to as “green manures”, too. Cover crops typically consist of plant species that are able to germinate and establish quickly. They require very little management and input. Vegetable crops and cover crops can be planted simultaneously or successively. During a successive planting, the cover crop is typically planted in the fall following the final vegetable crop harvest.

By filling in the vacant spaces between the vegetable crops, cover crops reduce weeds. This saves on weed management techniques like herbicides, mechanical treatments, and manual removal required to treat weedy species. All can be undesirable and expensive. Cover crops also add diversity to a home garden, which improves soil health. They reduce the need for fertilizers, further reducing costs.

Crimson clover cover crops between almond trees (CA) manage weeds, provide organic matter, fix nitrogen, and more – besides, they are pretty! Credit: Luke Milliron

Gardeners can also buy cover crops that attract butterflies and pollinators, which improves the yield/output of the vegetable crop. Increasing pollinator presence in your home garden also benefits your surrounding plants and flowers.

Legumes (pea and bean species) are capable of a process known as soil nitrogen fixation. Legumes have nodules on their roots where beneficial microbes live. These microbes can take nitrogen from the air, and convert it to “food” for the plant. In exchange, the plant gives sugars back to the microbes.

Nitrogen is a common component of fertilizers. So, using legumes as cover crops in a home garden can reduce the need for fertilizer, and reduce home gardening costs.

The choice of a single cover crop species or mix of several species, as well as planting and management of cover crops, depend on the desired outcome and the individual gardener’s goal.

Legumes (N-fixation)

• Clover
• Vetch
• Field Peas
• Cowpeas
• Mung Beans

Grains/Grasses (Nutrient Scavengers-use excess soil nitrogen and reduce weed pressure)

• Annual Ryegrass

• Winter Rye
• Barley
• Millet

Broadleaf/Tillage Species

• Nitro/Tillage Radish
• Buckwheat
• Mustards/Brassicas
• Flax
• Sunflower

Contact your state’s Land Grant Universities’ Cooperative Extension System program or a local seed vendor for cover crops suitable in your area.

Kelley House, Certified Professional Soil Scientist, Duraroot Environmental, LLC

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