Friday, November 2, 2007

Turf - Critical Temperatures

Cool season and warm season turfgrasses respond differently to temperatures. The following is some information on this topic.

Temperatures Affecting Turfgrass

This info is from a report published by the North Carolina State University Turf Council (“Soil Temperature Reports Aid Managers” March 31, 2005) shows the impact of soil temperature on cool and warm season turf:

Excerpted from the report:

The following is a partial list of soil temperatures (F) at the 4-inch depth that should be of the association with certain biological events.

Cool Season Grasses (fescue, bluegrass, ryegrass):
  • 90°F Shoot growth ceases.
  • 77°F Root growth ceases.
  • 70°F Maximum temperature for root growth of any consequence.
  • 70°F Time to plant grasses in late summer.
  • 60°-75°F Optimum temperature for shoot growth.
  • 50°-65°F Optimum temperature for root growth.
  • 40°F Shoot growth ceases.
  • 33°F Root growth ceases.
  • 20°F Low temperature kill possible if temperature subsequently drops
    rapidly below 20F

Warm Season Grasses (bermudagrass, zoysia):

  • 120°F Shoot growth ceases.
  • 110°F Root growth ceases.
  • 80°-90°F Optimum shoot growth.
  • 75°-85°F Optimum root growth.
  • 74°F Optimum time to overseed bermudagrass with ryegrass in the fall.
    Time to plant grasses in the spring.
  • 64°F Expected spring root decline is triggered and roots turn brown
    and die within 1 or 2 days.
  • 50°F Root growth begins to slow below this temperature.
  • 50°F Chilling injury resulting in discoloration is possible.
    50°F Initiation of dormancy occurs resulting in discoloration.
  • 25°F Low temperature kill possible.

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