At this time of year, I tend to get questions about the purple flowers or dandelions in home lawns and what can be done now to get rid of them. The answer is really nothing right now. These winter annuals are nearing the end of their life cycle, and it is neither the time nor financially feasible to do anything about them at this point. I found a short article from the K-State Research and Extension Horticulture department regarding winter annual weeds, and what you can do to eventually remove them from your lawn.
The plant with the little purple flowers that have been showing up in home lawns is called henbit. If you are not sure this is what you have, check the stems. If they are square rather than round, you have henbit. A plant that also is low growing but has round stems and tiny white flowers is chickweed.
Both these plants are winter annuals and start to grow in the fall. They spend the winter as small plants and so most people do not pay much attention to them until they start to flower in the spring. Trying to kill either one at this late stage with a herbicide usually is a waste of time and money. Though plants may be burned back, they will rarely be killed. So what should you do? Remember, these are winter annuals that will die as soon as the weather turns hot. Keep the lawn mowed until nature takes its course.
However, you can do something this fall that will help next spring. Henbit and chickweed usually germinate about mid-October. Spraying with 2,4-D, Weed-B-Gon, Weed Free Zone, Weed Out, or Trimec in late October to early November can go a long way toward eliminating these plants as they are small and relatively easy to control. Choose a day that is at least 50 degrees Fahrenheit so the young plants are actively growing and will take up the chemical.
Spot treating will probably be needed in the spring (March) to catch the few plants that germinate late. Use Weed Free Zone, Speed Zone, Weed Out, Weed-B-Gon, Trimec or one of the special henbit herbicides early in the spring before they have put on much growth.

Alicia Boor is the Agriculture and Natural Resources agent for Barton County K-state Research and Extension. Contact her by email at aboor@ksu.edu or call 620-793-1910.