November 3, 2011

Yard and Garden: Fall Lawn Care

By Richard Jauron
Iowa State University Extension Scott County

As lawn mowing comes to an end, it is a good time to perform other lawn maintenance. Iowa State University Extension horticulturists address fall lawn care. To have additional lawn questions answered, contact them anytime at or by calling 515-294-3108 Monday through Friday from 9 a.m to noon and 1-4 p.m.

Is fall a good time to fertilize the lawn?

Fall is an important time to fertilize the lawn. Spring and late summer fertilizer applications mainly stimulate leaf growth. A fall fertilizer application promotes root development, enhances storage of food reserves and promotes early green-up next spring. Early November (once the turfgrass foliage has stopped growing) is the ideal time to apply fertilizer in fall. Nitrogen is the most important nutrient to apply in fall. Apply one pound of actual nitrogen per 1,000 square feet.

When should I stop mowing the lawn in fall?

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

Do I need to rake 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. A thick layer of leaves (little or no grass is visible) will need to be raked up and removed. It’s possible to deal with a small amount of leaves (areas of grass are clearly visible) by shredding the leaves with a mulching mower. Small amounts of leaf debris will filter down into the grass.

Are broadleaf herbicides effective when applied during dry weather?

Broadleaf herbicides are most effective when applied to weeds that are actively growing. During prolonged periods of dry weather, some weeds are likely to curl up or wilt. An application of a broadleaf herbicide to drought stressed weeds likely will be less effective as wilted foliage will absorb less herbicide than healthy foliage.

Broadleaf herbicides can be applied from mid-September to early November in Iowa. In dry fall weather, wait for a good rain or irrigate the lawn before applying a broadleaf herbicide. One-half inch or more of water (either from rainfall or irrigation) will quickly revive most drought stressed weeds.