When to Apply Chickweed Killer

Pre-emergent Herbicide Application

• A number of pre-emergent herbicides are recommended for the control of chickweed. Pre-emergent herbicides control weeds by retarding the germination of weed seeds. Recommended products for chickweed include dacthal, oryzalin, simazine, dithiopyr, isoxaben, pendimethalin or prodiamine, as suggested by Richard L. Duble in "Turfgrasses." All chemicals are sold under different trade names and are best applied between early fall and early winter before weeds emerge.

Post-emergent Herbicide Application

• As the name suggests, post-emergent herbicides are applied to already growing weeds and work best on weeds in the seedling stage of growth. Recommended post-emergent herbicides for chickweed include dichlorprop, triclopyr or dicamba.

  Best time to use these products is during winter and early spring. Use products containing triclopyr for chickweed control only in cool season grasses.

Herbicide Use Recommendations

• Follow all directions for herbicide applications carefully to minimize damage to desirable plants in the landscape. Note whether the chemical can be mixed in soil and whether it is recommended to disturb the soil after application. Many chemicals are not intended for use in food crop areas.

Cultural Weed Management

• Controlling chickweed with chemicals should be considered the last option in cases where cultural control strategies prove ineffective or are impossible, recommends the University of California Extension. Cultural control methods include mulching, hand weeding and cultivation. Chickweeds in the early stages of growth are easily controlled before the roots grow too deep and before the plants set seed. Monitoring the site regularly and removing weeks in a timely manner minimizes or eliminates the cost and the potential environmental hazards related to the use of herbicides.