Fall can be a great time to renovate your lawn. Seeding is easier because the seedlings won’t experience as much heat stress. Avoid adding additional nitrogen as it will over-stimulate the existing grass, thereby crowding out the new seedlings. Fine fescues will use less water, and tall fescues have longer roots. Figuring out why your lawn isn’t doing well before renovating it, will save you time and money. Go to: https://extension.umn.edu/lawn-care/renovating-lawn-quality-and-sustainability for more information. If you are laying down sod it, too, benefits from cooler temperatures in the fall and will require less water.
When temperatures are between 50 and 75 degrees your grass starts storing nutrients in its roots, to be used next spring, so late August through mid October is the optimal time to fertilize. Applying fertilizer in the spring leads to fast growth that suffers in the summer heat. Applying it after the ground is frozen creates run-off pollution and wastes your money. You should start with a soil test (go to: https://soiltest.cfans.umn.edu/ or e-mail email@example.com ) before applying fertilizer.
Fall can also be a great time to kill those perennial broad-leaf weeds. They, too, are storing nutrients in their roots, so taking care of them in the fall eliminates them next spring. If using an herbicide (or fertilizer), always read ALL the instructions and follow recommendations for application rates, weather conditions and personal protection. Spot-treating may be the most economical and safest way to apply broad-leaf weed control products. Herbicide/fertilizer combination products can compromise both the fertilizer and the weed control effectiveness due to the ‘water-in’ vs. ‘leave-on-the-leaf” instructions. Crabgrass sprouts earlier in the year, so don’t use a crabgrass pre-emergent product in the fall. Go to: https://extension.umn.edu/planting-and-growing-guides/lawn-care-calendar for more information.
Continue mowing until the grass stops growing, sometime in October. Make sure your mower blades are sharp and remove no more than the top 1/3 of grass length in any one mowing. During warm weather 3-4” long grass keeps the ground moister. But if you leave it long over the winter it becomes a vole paradise! Leaving (small) grass clippings on your lawn returns their nitrogen to the lawn and mulching blades help keep the clippings small.
Bee populations have been declining in part due to habitat loss and pesticide use. Having flowering plants in a lawn will help bees, and you also increase your lawn’s resilience; it will have healthier soil and need less watering, mowing, and fertilizer. White clover, Creeping thyme, Self heal, and Ground plum are low-growing flowers that tolerate mowing down to 3 inches. Turf areas that have little foot traffic or that are primarily aesthetic are great locations. Examples are: steep slopes, right of ways or easements. Do not use broad-leaf weed control on Bee Lawns: it will kill all the flowers that the bees need. Spot treat very carefully. Go to: https://bluethumb.org/turf-alternatives/pollinator-lawn/ for more information.
Photo credit: University of Minnesota Extension