We know it is important for us to drink plenty of fluids to prevent dehydration, especially during the heat of summer. Our lawns are no exception. They too can easily become dehydrated when rain showers are scarce and temperatures of summer soar into the upper nineties and even higher as we have encountered recently.
A healthy lawn is a tremendous air conditioning system as it transpires water during the metabolic processes going on within each grass plant. In fact the temperature just above the canopy of healthy turf can actually be cooler than the air a few feet above and as much as forty degrees cooler than a concrete parking lot. However, without an adequate supply of water these tiny manufacturing systems are unable to moderate temperature changes of cell protoplasm, maintain cell turgidity and opening of stomata, or efficiently transport nutrients and carry on photosynthesis. Therefore, they become weak and susceptible to secondary stresses of insects, diseases, weeds, traffic, etc. and ultimately may not be able to recover.
To prevent lawn dehydration, it is important that supplemental irrigation water be provided when rainfall is inadequate. Depending on environmental and physical conditions of temperature, wind, cloud cover, soil type, etc., a general rule of thumb for water needs of an actively growing lawn during the summer will be one to one and one-half inches of water per week.
A thorough deep watering once or twice a week that wets the soil several inches deep is much better than applying just a light sprinkle daily. Watering early enough in the day to allow the foliage to dry before nightfall reduces disease pressure.
Keep a close eye on your lawn during these extreme days of high temperatures and little rainfall just as you do for yourself, children and pets as these extremes do have an effect on your lawn’s health if it becomes dehydrated. Signs of dehydration include curling and shriveling of leaf blades, a grayish hue in leaf color, and lack of recovery from traffic (foot printing).
Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. firstname.lastname@example.org