ISSUE 12 July 19, 2001
HOT, DRY WEATHER EQUALS BROWN LAWNS
The quick turn around of the lawns in our area - especially those of the Kentucky bluegrass mixes or blends - from lush green to straw brown is perfectly normal for the species, and in most cases is not an indication death. Kentucky bluegrass and itís usual co-hosts in the most lawns, have the unique ability to go into this dormant phase and recover when the rains come back again in the fall. Lawngrass that can stay green through this period without additional irrigation are usually either tall fescue, buffalograss, or some other warm season grass that thrives under these conditions.
To water or not, that is the question: If water is to be applied to a lawn, a decision must be made as to whether or not it is intended to keep it green, or to simply keep it alive through the dormant period. If it is to keep it green, then between 1-1Ĺ inches of irrigation water needs to be applied weekly. This amounts to 640 gallons of water for every 1000 square feet of lawn per inch of water applied. If the intent is to simply help it through the drought/dormancy period, then about 0.25 inch of water needs to be applied every week to10 days. If no precipitation occurs for a 10-day period, consider getting that quarter-inch down.
Mowing is stressful to turfgrass anytime, but especially so during the droughty weeks of July and August. Avoid mowing if possible, but if it is needed, try and do it going into the evening hours and follow it up with an irrigation the morning after. Set the mower high - 3 inches for each mowing, and if possible, make turns off the grass to keep from getting "wheel burn" so common on lawns at this time of year
Ron Smith, Ph.D.
NDSU Extension Horticulturist and Turfgrass Specialist