Yard and Garden: Properly Treating Lawns In Fall for Spring Results


September 16, 2015, 4:57 pm | Richard Jauron, Greg Wallace

AMES, Iowa – With fall right around the corner, this is the perfect time to treat lawns for optimal spring performance. Treating now assures lawns will be ready for spring growth. Here are some tips from Iowa State University Extension and Outreach horticulturists on how to best prepare lawns and avoid spring weeds. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.

When is the best time to apply a broadleaf herbicide to the lawn?

Fall (late September to early November) is the best time to control perennial broadleaf weeds in the lawn with broadleaf herbicides. In fall, perennial broadleaf weeds are transporting food (carbohydrates) from their foliage to their roots in preparation for winter. Broadleaf herbicides applied in fall will be absorbed by the broadleaf weed’s foliage and transported to the roots along with the carbohydrates, resulting in the destruction of the broadleaf weeds.  

Effective broadleaf herbicides include 2,4-D, MCPP, dicamba, triclopyr, and others. The most effective broadleaf herbicide products contain a mixture of two or three herbicides as no single compound controls all broadleaf weeds. Broadleaf herbicides can be applied as liquids or granules. Before applying any herbicide, carefully read and follow label directions.

Weed Removal

How can I control “creeping Charlie” in my lawn?

Ground ivy (“creeping Charlie”) in lawns can be controlled with broadleaf herbicides. Products that contain 2,4-D or triclopyr are most effective. 2,4-D is an active ingredient in many broadleaf herbicide products. Triclopyr can be found in Ortho Weed-B-Gon Chickweed, Clover, and Oxalis Killer for Lawns and several other products. Two applications are necessary to effectively control ground ivy. In Iowa, herbicide applications should be made between late September and early November. The first application should be made in late September/early October, the second a month later. 

How can I control violets in my lawn?

Digging up the plants is an option for home gardeners with a small infestation of violets. Broadleaf herbicides are the most practical solution when dealing with large numbers of violets. Broadleaf herbicide products containing triclopyr provide the best control of violets. Applications can be made in spring or fall. Two applications, three to four weeks apart, are usually necessary to destroy violets. The complete elimination of all violets in the lawn is extremely difficult and often unattainable.

How do I control white clover in my lawn?

White clover is common in many lawns because it is a prolific seed producer and adapts well to mowing and other lawn care practices. Its presence is often a sign of low nitrogen fertility.  

White clover in lawns can be controlled through proper fertilization and the application of broadleaf herbicides. Spring (mid-April to early May), mid-September, and late October/early November are excellent times to fertilize Kentucky bluegrass lawns in Iowa. Herbicides that contain MCPP, dicamba, or triclopyr provide excellent control of white clover. An application of 2,4-D (alone) is not effective in controlling white clover. Applications of broadleaf herbicides in late spring/early summer provide some control of white clover. However, fall applications (late September to early November) are most effective.  

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