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Lawn Care Tips for Fall

Source: Brenda Postels, University of Minnesota Extension

Fall is the best time to improve the condition of your lawn.  Killing weeds, fertilizing, reseeding, and aerating can go a long way in greatly improving your lawn for next year.

Did you have a lot of weeds this year?  Fall (Early September to Mid-October) is the best time to control perennial broadleaf weeds in the lawn with broadleaf herbicides. In fall, perennial broadleaf weeds such as dandelions, creeping Charlie, plantain and clover 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 weed’s leaves AND the roots.

Effective broadleaf herbicides include 2, 4-D, MCPP, triclopyr and others. The most effective broadleaf herbicide products usually contain a mixture of two or three herbicides, as no single compound controls all broadleaf weeds. Broadleaf herbicides can be applied as sprays or granules. (Sprays are generally more effective than granular products in controlling broadleaf weeds.) Don’t bother trying to control crabgrass in the fall.  Crabgrass is an annual and will die in the fall anyway.  If you have a crabgrass problem, you will want to be SURE to apply a pre-emergent herbicide in the spring, before the ground warms up and the annual crabgrass seeds germinate. Before applying any herbicide, carefully read and follow label directions.  It is the law! 

Up until late September is the best time to seed new lawns and over seed existing lawns.  A late summer seeding has several advantages over spring seeding. The seeds of cool-season grasses germinate quickly in the warm soil of late summer. The warm days and cool nights of early fall promote rapid turfgrass growth. The growing grass also has less competition from weeds as few weed seeds germinate in late summer or fall.  

Up until about Mid October, (after the grass has stopped growing) are excellent times to fertilize cool-season lawns in Minnesota. Mid-September fertilization helps the grass recover from stressful summer weather. An application of fertilizer in mid-October promotes root growth and early green-up next spring. Apply no more than 1 pound of nitrogen per 1,000 square feet in a single application. Lawns also can be fertilized in spring (Early May to Mid-June).  

Anytime from now through mid-October is also an excellent time to aerate lawns growing in heavy, clay soils and those subject to heavy foot traffic. Aeration relieves soil compaction, improves water and nutrient movement in the soil, and prevents thatch accumulation.  Aerate lawns with a core aerator. Core aerators have hollow metal tubes or tines that remove plugs of soil. Remove soil cores that are approximately three-fourths of an inch in diameter and 3 inches in length. When completed, properly aerated lawns should have 20 to 40 holes per square foot. This usually requires several passes of the core aerator. Lawns also can be aerated during the month of May. 

Continue mowing the lawn until the grass stops growing in fall. The foliage of Kentucky bluegrass and other cool-season grasses usually stops growing in mid to late October or early November in Minnesota. Mow lawns at a height of 2½ to 3 inches in fall. When mowing, never remove more than one-third of the total blade area at any one time. Accordingly, a lawn being mowed at a height of 3 inches should be cut when it reaches a height of 4½ inches. 

You can find a Minnesota Lawn Care Calendar on the University of Minnesota Extension website or by clicking here.  For more information, contact your local county Extension office.

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