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Overseeding Warm Season Grasses

For successful overseeding, you need to:

  • Choose the proper seed.
  • Properly prepare for and time the overseeding.
  • Carefully maintain the overseeded grass.
  • And attentively manage the spring transition back to the warm-season grass.

You also need to maintain a healthy warm-season turf all year. It's particularly important to keep the soil fertile, relieve soil compaction and prevent excessive thatch.

The proper seed is the grass with the characteristics best suited to your particular needs. Annual ryegrass has fast been replaced by perennial ryegrasses because of their improved quality, stress and pest tolerance and manageability. Use seed treated with fungicides, too, such as Apron or Koban. This is particularly true for early fall, since seedling blight diseases can be a problem at this tim

The right seeding rate depends on how you want it to look and how much traffic the turf will bear. Higher-traffic areas need higher seeding rates. However, higher seeding rates may also mean a more difficult spring transition.

Conditions for overseeding:

  • Soil temperatures at a 4-inch depth approaching 24°C. 
  • Night temperatures consistently around 10°C.
  • Average midday temperature below 21°C, or two to four weeks before the average annual first killing frost.


The best way to make the actual overseeding successful is to get good soil-to-seed contact. Seedbed preparation generally consists of close mowing or scalping, with some light vertical mowing, and sweeping or vacuuming up the loose plant debris.

In Fieldclimate.com we show optimum dates for overseeding with either  WARM (GPW) or COLD season gras species  (GPC).

Example1: Optimal time span to overseed with cold season gras species during late summer and autumn.

Example2: Optimal time span for warm season gras species.
 

Sources: 
 

Gil Landry, PhD., Coordinator - The Center for Urban Agriculture, The University of Georgia.

Fall is overseeding time (from Mid of August till Mid of October).