It’s important to keep your grass 2 to 2-1/2 inches tall throughout the fall. If your grass gets much longer (more than 3 inches) it will mat, leading to winter lawn disease problems such as snow mold. If you cut it shorter than 2 inches, you’ll severely limit its ability to make and store food for growth in the spring.
Lawn raking in the fall removes excess organic debris, and can help maintain water quality. In winter, freezing and thawing can cause leaves, dead grass plants, and other organic debris to release soluble forms of phosphate (and nitrates). If these chemicals run off frozen ground during spring snow melt and early spring rains, they can end up in surface water.
Keep grass clippings, leaf litter, and other organic debris off driveways, sidewalks and streets.
You have several options when it comes to disposing of fallen leaves. The preferred way is to compost them, because composting keeps leaves out of streets and storm sewers. You can also use fallen leaves, whole or chipped by a power mower, as winter mulch around rose bushes and landscape plants. Leave fallen leaves on your lawn and make several passes over them with a power mower, chopping them into a thin layer fine enough to stay on the lawn without causing damage while providing nutrients for the grass. You can also bag leaves for disposal by municipal authorities.
Even though temperatures might be cooler than in summer, your lawn still needs water. Since lawn grasses continue to grow throughout the fall, watering is still important to sustain growth. Go ahead and water as needed until the ground is cold and beginning to freeze. If you have an automatic irrigation system, avoid damage by having it blown out with compressed air before water freezes in the pipes and sprinkler heads.
Apply a final dose of fertilizer in mid- to late October. You’ll provide your grass with nutrients that will be absorbed and stored until needed for spring growth. Lawns that have received late-season fertilizing are often the first to begin growing in the spring.
“Winterizing” types of fertilizers containing high amounts of phosphorus are only necessary if a reliable soil test indicates a shortage of phosphorus. Otherwise, use a standard lawn fertilizer.
Fall is a good time to control perennial broadleaf weeds such as dandelions, plantain, clover, and creeping charlie. Limited numbers of weeds can be removed by hand. If your weeds are few and scattered—or confined to a few small areas—spot-treating them with herbicide is usually sufficient. Weed-control products sold in ready-to-use spray containers make spot treatment easy. Be sure to complete treatments when temperatures are above 50 degrees—your herbicide needs time to do its job before winter cold sets in.
Don’t choose your weed-control strategy without a careful evaluation of the number and types of weeds in your lawn. Remember—you don’t need to apply herbicides over your entire lawn unless there’s extensive weed infestation. And don’t worry about controlling crabgrass—that’s done more effectively in spring. The first hard frost will kill annual weedy grasses.
Fall is the best time of year to establish or repair lawns by seeding or sodding. Seeding should be completed by mid-September. Cool temperatures usually make fall seeding or sodding successful. Be sure to complete your sodding before very cold weather sets in.
Lawn Care and Water Quality Program
Pesticide & Fertilizer Management Division
Minnesota Department of Agriculture (MDA), 625 Robert Street N, St. Paul, MN 55155-2538, firstname.lastname@example.org