Archive for Thursday, September 25, 2008

Compost and cover for your vegetable garden

September 25, 2008


Fall is finally here! I am usually more excited about spring, but this year is different: I have been waiting all year to make improvements to the vegetable garden.

The garden grew well enough this year, but I know that the key to the healthiest crops is the soil. Adding organic matter reduces compaction and thus improves root growth, and a cover crop helps retain and recycle nitrogen and other nutrients vital to plant health.

Lawrence residents are very lucky to have a good supply of organic matter: the city compost. The giveaway runs from 8 a.m. to 3 p.m. today and Friday, and 8 a.m. to 4 p.m. Saturday, or for as long as supplies last, at the Wood Recovery and Composting Facility, 1420 E. 11th St.

Apply the compost at a rate of 50 to 100 pounds per 100 square feet of garden for best results. If that sounds like too much math, spread the compost 1 1/2 inches thick across the entire garden, and till or spade it into the soil to a depth of 6 inches.

If you choose to use homemade compost or have another source, make sure the compost is completely decomposed or it could be a problem instead of a good thing. Finished compost is dark and crumbly and has a rich, earthy smell.

Manure, grass clippings and leaves also need to decompose before being added to the garden. If they are still decomposing, they can tie up soil nutrients that your intended crops need. Sometimes this fresh organic matter provides an abundance of nitrogen, and you will end up with big plants but little produce.

Once I get the compost worked into the soil, I will seed annual ryegrass as a cover crop.

Cover crops are grown for soil protection and improvement instead of for harvest. There are many types of plants that make great cover crops in this area, and the decision about what type of crop to plant as a cover should be carefully considered. Annual ryegrass is easy to find and will be easy to incorporate in the spring.

Spread the seed over the soil with the same drop-seeder used for the lawn. Annual ryegrass seed does not need much soil cover; a friend taught me to flip a leaf rake upside-down (tines pointed up) and drag it lightly across the soil. This is a great way to get the seed in good contact with the soil without burying it too deep. Water the seed if needed for germination and forget about it until next spring.

Annual ryegrass is one of several winter annual crops (grow well in cool weather, but only live one season) available for cover. Some perennials like alfalfa or red clover are also good choices for cover crops. A third class, summer annuals, is seeded in the spring or summer.

Some other popular options for winter annuals are hairy vetch, crimson clover and winter wheat (rye).

To keep the cover crop from becoming a problem later, incorporate the crop into the soil before it seeds. Cover crops can also be mowed in the spring to prevent seeding.

Extension Master Gardeners are happy to answer your compost and cover crop questions at 843-7058 or

- Jennifer Smith is the Douglas County Extension AgentHorticulture for K-State Research and Extension.


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