Soil temperature can be a determining factor in the health and wellbeing of your lawn. Intense summer heat creates stressful growing conditions for your grass season mixes. Cool season grass mixes, used a lot in the north and mid-atlantic regions, experience optimal growth conditions when soil temperatures are between 60 to 75 degrees, which can seem like a narrow range during mid and late summer heat waves. Already, as of mid-June, some parts of the region have seen soil temperatures exceeding 75 degrees at 2 inches. No need to panic, your lawn will not just up and die, but do keep monitoring your landscape for signs of stress.
While there is no way to control the temperature, you may be able to mitigate some of the myriad other possible stressors on your landscape to help it handle the heat stress. Be mindful of diseases and pest problems on your lawn, controlling these issues will aid in keeping your lawn on the right track towards health and vigor. If you have a lawn care program in place and you are unsure as to whether pest and disease control are included or have concerns, consult your arborist. Use appropriate cultural measures; mow properly, irrigate sufficiently and at the right time and fertilize adequately. When mowing do not remove more than 1/3 of total blade surface, proper grass height is between 2 to 3.75 inches with longer grass being more tolerant of stress (http://www.turf.msu.edu/mowing-lawn-turf). Irrigate as evenly as possible, all systems will have areas that receive more or less water than others, monitor this closely and attempt to correct the situation with additional moveable sprinklers, adjust heads or use portions of drip hose where necessary. Too much water can be equally damaging to turf, keep an eye on the weather, if rain is forecasted, skip the sprinklers. Fertilization will be part of your lawn care program, if you do not currently have a program or have questions or concerns, consult with your arborist to develop a program tailored to your landscape’s needs.
It is best to avoid compounding stressors if possible, you know your landscape best, monitor conditions closely and discuss any changes with your arborist. Avoid watering your lawn during the hottest hours of the day under direct sunlight for long periods of time, watering in the early morning and the evening may yield better results. Continue with your landscape treatments and programs as prescribed by your arborist, should weather or environmental conditions preclude a treatment at a certain time your arborist will inform you and reschedule treatments when conditions improve.