Most of the weeds you can see now are what we term winter annuals. They grow annually from seed during the fall through early spring. Many of these weeds (henbit, annual bluegrass, chickweed, etc.) will eventually die when the temperatures finally warm up and stay there.
They are flowering heavily now which is why you see the bright purples, yellows, and whites in the landscape. Since they are flowering and into a reproductive stage, they will be completing their life cycles soon and dying. Spraying them with an herbicide to kill them at this time may be of little value.
Mowing the lawn to remove most of their leaf, flower and seedhead canopy before the seed mature which will help reduce next fall’s seed source. Also, vow to use a preemergence herbicide late next summer or early fall to prevent their prodigy from germinating later or apply post-emerge herbicide earlier in the winter when these young weeds are small and actively growing.
Many of these dying weeds create additional problems when they die. They leave small openings in the canopy of the permanent turf for summer annuals such as crabgrass, goosegrass, prostrate spurge and the like to take their place.
There are a few perennial winter weeds that you may want to control now such as wild garlic, dandelions, clover, plantains, etc. so broadleaf post-emerge herbicides such as 2,4-D, dicamba, clopyralid, metsulfuron, and others may be used effectively.
For further information on specific herbicides look for the Extension publication 1532 Weed Control Guidelines for Mississippi online or at your local Extension office.
Published March 7, 2011
Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. email@example.com