By Grady Miller and Fred Yelverton
Record high temperatures in August combined with record low rainfall has taken its toll on tall fescue and tall fescue/Kentucky bluegrass lawns around the state. September marks the start of the normal seeding and renovation for cool-season grass species across most of NC.
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 outdoor water restriction. Typically, September seeding is desirable even though daytime temperatures are still high. However, night temperatures are decreasing and given adequate moisture, tall fescue and Kentucky bluegrass will germinate and grow very well. Early seeding in September is beneficial because this allows the tall fescue to mature in the fall. Going into winter, the plant is healthy and the fescue/bluegrass will tolerate preemergence herbicides well in February and March. Late seeding often results in immature fescue that can be injured by premergence herbicides. This dilemma (seed or wait) is best decided by your present soil condition and the ability to provide water. If you can only broadcast seed and your soil is too hard to core cultivate (aerify), then seeding is probably not advisable. In this situation, it is advisable to wait until there is a soaking rainfall so that the soil surface can be core cultivated.
If the lawn can be slit seeded then it would be ok to go ahead and seed. The daytime air temperatures are still warm but the night temperatures and humidity levels are starting to moderate. In the absence of soil moisture, the seed may remain protected in the soil until moisture is present. Given some rainfall or some irrigation (within your present restriction) the seed can germinate.
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. Remember, it takes about 5 to 7 days for fescue to germinate this time of year. If you are currently under one-day per week water restrictions this scenario is very possible. In that case it is best to not water. When a soaking rainfall occurs, germination and growth will progress as normal as long as temperatures are suitable. If the temperatures are consistently below 65/45 then the stands will likely be thin.