Design or redesign a landscape

Estimate the water needs of landscape plants

Photo: Turfgrass and golf ball and hole

Determining a plant adjustment factor for turfgrass

To calculate the amount of water lost by a plant to evapotranspiration, you'll need the plant adjustment factor, KL. This is a factor that accounts for the distinctive water-regulating differences of various species.

Obtaining an adjustment factor for a turfgrass is a relatively straightforward matter: you can simply look it up in a table.

To see a summary of the KL values recommended for turfgrasses, refer to Table 1.

Scientists have been able to specify the KL values for various species of turfgrass by applying methods developed for agricultural crops. This strategy works because turf usually is relatively homogeneous, as is the typical agricultural crop, and because a turfgrass conforms relatively well to the assumptions inherent in the definition of a reference ET plant.


You want to estimate the amount of water lost to evapotranspiration in September by your landscape's Bermuda grass, a warm-season turfgrass.

  • Referring to Table 1, you see that the factor for September for a warm-season turfgrass such as Bermuda grass is 0.62.
  • If no other plants exist in your landscape, or if your only concern at present is to find out about the Bermuda grass's need for water, then you can proceed to multiply this factor by your locale's September ET0.
  • If, however, you also want to determine the water needed by the other plants in your landscape, you'll need to derive adjustment factors for those plant types as well.
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