Why Some Warm Season Grasses are Slow to Green Up

  Some warm season grass lawns (Zoysiagrass and

Bermudagrass) have been slow to come out of 

         winter dormancy due to the cool weather 

condition this spring. 

UGA Extension Gwinnett has received numerous calls from both homeowners and professionals concerning their warm season grass lawns, mostly bermudagrass and zoysiagrass being slow to green up. UGA Extension Turfgrass Specialist Clint Waltz has written the following to address the issue:

While it is the end of May and many warm-season grass species have greened-up, some

bermudagrass and zoysiagrass lawns still have a significant amount of old, brown, leaf material

in them. This is likely the result of several compounding factors. The impact of last fall’s long,

hot, dry weather are likely affecting green-up this season, especially in non-irrigated lawns. A

second factor influencing green-up could be all the rainfall this winter. Water is a good buffer of

heat. Meaning that it takes more energy (i.e. from the sun) to warm a wet soil than a dry soil. To date, the average four-inch soil temperature for the entire month of May in Griffin, GA – central for the state – is 71.2 degree. That is 5.6 degrees lower than for the same time last year. Similarly, the average maximum air temperature this May has been 8 degrees cooler than May 2019. Lastly, of the pictures, descriptions, and observations I have made, the lawns with considerable brown have a higher mowing height than is recommended for bermudagrass and zoysiagrass. The mowing range should be one to two inches. The extra leaf canopy and thatch can act as an insulator, like the pink stuff in your attic and walls, preventing the sun’s energy from warming the soil quickly. For these lawns I have suggested the grass be mowed as low as possible and remove all the leaf biomass. The objective is to open the turf canopy, permitting sunlight to reach the soil surface. Taking it a step further, consider core aerification. Opening holes into the soil profile permits warm air into the root zone, warming the soil from the inside-out. By warming the soil, rhizomes will initiate new shoots, eventually reaching the soil surface and thickening the lawn