Late September a Good Time to Over-Seed Lawns

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Aug. 30, 2013

LINCOLN, Neb. — With the weather getting colder, September is a good time to start preparing lawns for the changing season, a University of Nebraska-Lincoln extension educator said.

"The weather seems to cooperate so well," said UNL extension educator John Fech of this time of year.

Fech said homeowners need to think of the individual needs of their lawns.

"Evaluate what your current status is," Fech said. "Evaluate what the highest priority is in terms of the biggest need."

If the homeowner determines that his or her biggest need is the lawn, late

August through the middle of September is a good time to over-seed, Fech said.

If over half of the homeowner's lawn is undesirable weeds and grasses, treat the lawn with Roundup. This will kill the lawn so that it can be replanted. Then rake it until there is bare soil showing; using a power-rake is best, Fech said.  

Owners should be careful when applying Roundup, Fech said.

"Be aware of all the plants around you that could be sprayed," Fech said.

Fech suggests using a barrier such as a plastic sheet between desirable plants and undesirable grasses during spraying. Adjusting the nozzle on the tank sprayer to allow for bigger droplets will also help keep the Roundup contained to one area.

Wind speed is also an important factor. Wind speeds should be 5 mph or less in order to ensure safe spraying, Fech said.

Fech recommends two types of grass for over-seeding; Kentucky bluegrass and turf-type tall fescue. If the lawn is in mostly shade, turf-type tall fescue would work best.  At least 3-4 hours of sunlight are required for turf type tall fescue to perform well. If the lawn is in a sunny location, either type can be planted.

"If your lawn is not in bad shape, just a little thin, simply skip the first step of applying Roundup," Fech said.

Fech said that even if homeowners decide not to apply Roundup, they still need to power rake their yard.

"Seed-to-soil contact is really important," Fech said. "Keep seed moist until it germinates."

Fech said that people should be careful when using a mixture of seeds not to stop watering after only one type of seed germinates.

"Some seed naturally germinates faster than others," Fech said. "Wait until all the grasses have germinated to reduce the frequency of watering."

Other tips include:

– Make sure to turn off and drain all automatic sprinkler systems by Halloween to prevent pipes from freezing.  You may wish to hire a sprinkler company to help

with this procedure.

– When applying nitrogen fertilizers, carefully follow the label and directions in regards to how much fertilizer to add.  When calculating how much fertilizer to put on the lawn, first consider the desired level of maintenance.  For low maintenance lawns, apply 1-2 pounds of actual nitrogen per 1,000 square feet per year.  Medium and high maintenance turfs should receive 2-3 pounds and 3-4 pounds per 1,000 square feet respectively. This amount should be spread out over the year, typically applied in late April around Arbor Day, early June around Memorial Day, early September around Labor Day and early November around Halloween.  Next, divide the amount desired expressed as a percentage by the concentration of fertilizer product to determine how much to spread over 1,000 square feet of the lawn. Then, measure the lawn area to be fertilized by marking off roughly rectangular areas and multiplying the length and the width of each. 

For more information on lawn fertilizers and how to reduce water pollution from fertilizers, visit

John Fech
Extension Educator
Douglas County

Heather Haskins
Student Writer

Sandi Alswager Karstens
IANR News Service

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