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.