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Prime lawn care season begins Labor Day

Power raking or core aeration is beneficial if the undecomposed thatch layer is more than one half inch thick. This grass plug shows very little thatch accumulation. Michael Vosburg / Forum News Service1 / 3
September is the most important month for lawn care, as proven by turf research. Michael Vosburg / Forum News Service2 / 3
Don Kinzler, Growing Together gardening columnist3 / 3

Gardening guidelines haven't changed much over the past century. Weeds are still a nuisance. Tomatoes require warmth to grow, just as they did when our great grandparents planted. But a few recommendations have changed, based on recent research, especially in lawn care.

Each spring we're excited about the smell of newly mowed grass, and caring for our lawn lets us enjoy the outdoors after a long winter. By fall, weeding, watering and mowing lose their luster a bit after a long summer.

But information from nearly all research universities proves that fall is the most important time for lawn care, and what we do in autumn affects our turf for the entire following year.

Mother Nature knows best. Grass naturally grows lush in fall, responding to autumn's cooler temperatures and increased likelihood of rain.

If we cooperate, and provide our lawn with what it needs to optimize fall growth, our lawns can be stronger than if we focus only on spring care.

Here's what to do this fall:

• Fertilize around Labor Day. Fall is the best time to fertilize lawns, better than spring. Nutrients are utilized more readily by grass plants in autumn, promoting a strong, deep root system that keeps grass greener longer and helps it green more quickly in spring. Fall fertilization makes lawns more drought-resistant next summer because of the increased root mass. If a secondary application is desired, apply around Memorial Day.

• Continue mowing at the same height. The healthiest grass height is 2 ½ to 3 inches and should be maintained until grass is dormant. The final mowing may be shortened for fall cleanup.

• Power rake in fall. If thatch (the tan, undecomposed layer of grass between blades and soil) is over one-half inch thick, power raking, also known as dethatching, is best done in September.

• Consider core aeration. Plugs of soil are removed, which improves water and air flow, especially on heavy soil and areas of high traffic, Core aeration removes thatch buildup better than power raking and September is preferred; spring is secondary.

• Conquer weeds this fall. Herbicide applications are more effective in autumn than spring, as weeds naturally carry the chemical downward into the root system. Difficult-to-kill weeds like creeping Charlie, violets and thistle are rarely killed with spring spraying, so fall weed control is a must. In fall there's less chance of collateral damage to flowers, gardens, trees and landscapes from spray drift.

• Seed grass before Sept. 15. Fall is the preferred season for establishing a new lawn, or thickening older turf. It's easier to maintain a moist seedbed for better germination, weed competition is less and cool fall temperatures encourage growth. If seeded by mid-September, grass germinates and establishes well before the end of the growing season.

• Late seeding. If it's not possible to complete seeding by mid-September, planting can be delayed until late October or early November just before soil freeze-up. Called "dormant seeding," grass seed will be in place, ready to sprout in early spring.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler's Greenhouse in Fargo. Readers can reach him at

He also blogs at " target="_blank">