What's a Cover Crop?

Master Gardener Susan Kowalchuk writes:

As the days grow cooler and the nights longer, my thoughts start to gravitate towards planning my garden for next year. I think about what worked, what didn’t, and what new growing challenge I may want to take on. This year I have decided to take on a new project prior to the spring planting season: planting a cover crop.

Although cover crops or “green manure” are routinely planted by farmers, it is not a typical practice for the home gardener. Cover crops are an excellent way to improve the soil by increasing organic matter and fixing nitrogen in the soil.  They also attract beneficials, loosen compacted soil, reduce erosion, and last by not least, control weeds.  Given that I spend quite a few hours cleaning up, clearing out weeds, and amending the soil in my community garden plot every spring, I was convinced that this was the way to go.

The next step was deciding what to plant. There are several factors to consider when choosing a cover crop: time of year you are planting, zone, whether the plant is an annual or perennial, and difficulty in taking the plants down to mulch into the soil.  This last factor is particularly important for the home gardener using only hand tools. Since I was planting in the late summer/early fall, and wanted to minimize my spring work, I narrowed my potential list down to the following:

 Barley ( Hordeum vulgare)–  is considered hardy in zone 6, but could suffer some winter injury. This is not a negative because the dead foliage still protects the soil and can be easily mulched. Living foliage will need to be turned in early spring.

Winter peas (Pisum stivum) and oats  (Avena sativa ) – These ideally should be planted in combination in the early fall. The peas fix nitrogen into the soil and the oats add organic matter. The peas will tendril around the oats. These crops should be cut down in early spring and turned.  To further enhance soil fertility, it is also recommended that you coat the pea seeds in an inoculant, which is a rhizobia bacterium. The bacteria help stimulate the formation of the nitrogen nodules on the roots, placing more nitrogen in the soil.

Cereal rye (Secale cereale) is a perennial and can be sown in late fall, making it a good choice for the procrastinator. One negative is rye can be difficult to turn over. Consequently, this task should be done in early spring before it develops seed stalks. It is also allelopathic, meaning it can inhibit seed germination.  Although this is great fro reducing weeds, you should wait a few weeks after you turn over the beds to plant.

Hairy vetch (Vicia villosa) should be sown in early fall. This crop is a good supplier of nitrogen, but it is slow to establish and should not be allowed to go to seed. Vetch can be turned mid to late spring.

Clover ( crimson – T. incarnatum  or white (T. repens) –  The advantages of clover to the home gardener is that that they are a low growing crop ( 18” for crimson and 6-8 for the white). Clover should be turned over before going to seed. The white is hardier in zone 6.

Cover crops seeds are not readily available in garden supply stores.  You may have luck with the stores that service farmers. Seeds can also be purchased from suppliers on line. If interested, you can start by checking out the following sites:

Sustainseed.com.

Johnnyseeds.com

Gardensalive.com

Groworganic.com

Territorialseed.com

Support Your Farmer:

LEHIGH VALLEY: If you would like to see fields planted in cover crops, plan a visit to the Seed Farm.  The Seed Farm is a nonprofit organization that offers a three-year new farmer training program and agricultural business incubator, in partnership with Penn State Extension’s Start Farming program and Lehigh County.   You can also find the Seed Farm at the Emmaus Farmer’s Market.

You could also visit the Seed Farm and other local farms during the Open Gate Farm Tours on October 12^th & 13th in Northampton County or October 20^th in Lehigh County.

BUCKS COUNTY: Sleepy Beaver Farm, located in Ottsville, grows a wide variety of vegetables.  You can find their produce at their Ottsville Market, the Easton Farmers’ Market and the Manayunk Farmers’ Market.

BERKS COUNTY: Oley Valley Organics is a family run organic farm in the heart of the Oley Valley. They grow strawberries, raspberries, asparagus and other vegetables.