Yard and Garden: Autumn Lawn Care

AMES, Iowa – Fall is a busy time for gardeners. With so much to do, lawn care is sometimes neglected. However, proper lawn care in fall helps ensure an attractive, healthy lawn next season. Important fall lawn care practices include mowing, fertilizing, controlling broadleaf weeds and raking. To have plant and garden questions answered, contact the Iowa State University Extension and Outreach Hortline at 515-294-3108 or hortline@iastate.edu.

Do I need to remove the leaves on my lawn?

Turfgrass plants use light, water and nutrients to manufacture food. In fall, lawn areas beneath large trees are often completely covered with leaves. The leaf debris prevents the turfgrass plants from manufacturing and storing food prior to winter. Leaves also may mat down and smother the grass over winter. A thick layer of leaves (little or no grass is visible) will need to be raked up and removed. A small amount of leaves can be chopped up with a mulching mower. Small quantities of finely shredded leaves will filter down into the grass canopy rather than rest on the grass surface. 

How long should I continue to mow the lawn?

Continue to mow the lawn until the grass stops growing in fall. The foliage of cool-season grasses, such as Kentucky bluegrass, stops growing when daytime high temperatures are consistently below 50 F. In Iowa, bluegrass usually stops growing in late October or early November. Once the foliage stops growing, the lawn mower can be put away for the winter.

How late can I apply a broadleaf herbicide to my lawn? 

Fall is the best time to control perennial broadleaf weeds (dandelion, plantain, clover, etc.) in the lawn with a broadleaf herbicide. Applications can be made from mid-September to early November in Iowa.  

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

When should I fertilize the lawn in the fall? 

Fertilizer applications can be made in mid-September and late October or early November. Mid-September fertilization promotes a moderate rate of shoot growth and helps to thicken the turf. An application of fertilizer in late October or early November (when the turfgrass foliage has stopped growing) promotes root growth and early green-up next spring. Apply 1 pound of actual nitrogen per 1,000 square feet in mid-September and late October or early November. 

What is the best way to store an opened bag of lawn fertilizer?

Store lawn and garden fertilizers in their original bags or containers so you will know the content and analysis of the product next season. Store granular fertilizers in a protected location where they will remain dry. Granular products absorb moisture from the air, causing them to cake up like cement. An excellent way to store opened bags of lawn and garden fertilizers is to place the bags in large containers, such as five gallon buckets, and cover with tight-sealing lids.  

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