Archive for Sunday, November 3, 2002

Winter weeds need to be controlled

November 3, 2002


The recent rains and cool nights have done wonders for our cool season lawns.

Unfortunately, they are exactly what winter annual weeds need as well. As we turn our gardening focus to preparing flower beds, vegetable gardens, and houseplants for the long winter, we need to take one last look around the lawn.

Now is the time to be controlling the two winter weeds, henbit and chick, and the ever-present warm-season dandelion.

Henbit is a rather showy spring blooming weed. The violet flowers, born on stems eight to 12 inches tall, are quite striking on a warm March day. They are commonly found in cultivated areas such as farmers fields, flower beds, gardens, and in the lawn. Chickweed, on the other hand, has a lower growth habit with creamy yellow blooms. Mix the two plants together and you can create a beautiful spring display with little effort. Keep in mind though, as with most weeds, they can be invasive and easily take over if left un-attended.

Because both weeds are self seeding, the plants that were there last year will not be the same plants that we see this year. They are, however, plants that sprout from the seeds that were dropped earlier this spring. The seeds have started to germinate and will continue to grow all winter long. Then, as the days get longer and the temperatures rise next spring, both will bloom and start the process over.

If you had henbit or chickweed last spring, now is a good time to control them for next spring. Start with mechanical controls. Hoe or lightly till bare soil in the garden and around flowers, trees and shrubs. For added control, apply a fresh layer of mulch, two to three inches should be enough. For hard to reach or non-cultivated areas, the broad-leaf weed killer Trimec is the best product to use. Spray on a sunny day when the air temperatures are above 55 degrees.

Avoid spraying newly sprouted grass seed as dieback may occur. Likewise, avoid spraying desirable trees and shrubs.

On a similar note, many gardeners try to attack dandelions in the spring when they are in full bloom. Unfortunately, this is not the best time of year to get them under control. Spring growth is caused by an upward flow of energy and nutrients from the roots. Sprayed herbicides do not move well from the leaves to the roots against this upward flow. Conversely, in the fall, the plants are preparing for winter by moving manufactured food from the leaves to the roots.

Herbicides sprayed now are taken quickly down to the roots where they can kill the plants. Choose a broad leaf weed killer such as 2,4-D and spray it on the warm fall day. As always, read and follow all label directions.

 Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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