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Fall Seeding of Cool-Season Grass Lawns - A Water Conservation Effort

August 21, 2008
by Charles Peacock, Grady Miller and Fred Yelverton

Tall Fescue Overseeding of Fall LandscapeDr. Charles H. Peacock, Dr. Grady L. Miller and Dr. Fred Yelverton Department of Crop Science NC State University

 

September marks the start of the normal seeding and renovation time for cool-season grass species in most of North Carolina. A common question is whether to begin fall renovation/seeding given the current environmental conditions? This is especially an issue considering most of the state’s urban areas are under some level of drought and outdoor watering restrictions. Typically, September seeding is desirable because night temperatures are decreasing and given adequate moisture, tall fescue, Kentucky bluegrass and the fine fescues will germinate and grow. Early seeding in September is beneficial because this allows these grasses to mature in the fall and therefore going into the winter the plant is healthier. There are a lot of reasons this is important.

  • First, this means that when the grasses resume normal growth in the spring, they have a more extensive root system which will better be able to tolerate hotter and drier conditions in the late spring and summer.
  • Second, a more mature turf tolerates preemergence herbicides better. Being able to use these materials in the spring to reduce weed competition means the perennial grasses can dominate rather than having a mixture of perennial grasses and annual weeds which will open the turf up for erosion problems and sediment loss under storm conditions.
  • Third, a mature turf provides for slowing runoff meaning better infiltration and soil water storage during rainfall. This reduces the dependency on irrigation for keeping the turf in the healthiest condition.

Fall aerification is always advisable providing the soil moisture conditions permit the process to be effective. Aerification works best if the soil is moderately wet. This then allows for broadcast seeding to be used. If the lawn can be slit seeded, that is even more effective since it provides for better soil/seed contact thus increasing the probability of the seeding being successful. The seed can remain protected until soil moisture is high enough for germination to occur. Seed (without moisture) can remain viable in the soil for an extended period of time. The worst situation is to irrigate to force germination and then stop. The seed will start to germinate and then the newly emerged seedlings will die. Remember, it takes 5 to 7 days for fescue to germinate and longer for Kentucky bluegrass.

Fall seeding of cool-season grasses, even under drought conditions does make WaterWise sense!