High heat and a lack off rainfall is double trouble when it comes to your cool season lawn- whether in NH or VT. Brown grass results within days if not weeks after prolonged heat and an absence of rainfall. What is a homeowner to do?
At this time of year, most action would be preventative such as proper cutting height (3”), lime, slow release fertilizer, mulched clippings to enhance organic matter, not mowing during the heat of the day, and having over seeded with a drought tolerant turf. In terms of no rainfall, unless you have an irrigation system setup properly or a very shaded lot- browning is as inevitable as bacon in skillet on Sunday morning. Hmm, you can just hear the sizzle and smell the lawn drying out to a golden brown!
On a serious note, its not the browning of your lawn that is a huge thing, but what might eat it while brown. You would never know of an attack because green turning to brown might get your attention while outside. What about brown staying brown? Nothing can indicate a problem- no color change. Now is the time to monitor for chinch bug, grub, or sod webworm activity either yourself or by hiring a professional licensed lawn care company.
In terms of watering, anything is helpful- but don’t expect that magical green you would see in the spring or fall. Providing an inch or more of water may not even be allowed if there is a ban like many towns are now experiencing here in NH. Since most grass needs about an inch per week, anything else helps to keep the dormant turf alive as it remains in a hibernation state. High heat will brown out and cause all kinds of blotches and spots in a treated or non-treated lawn setting- it is plain just too hot for cool season grass when the mercury rises above 85 to 90. High heat can cause white blotches on the leaf blade to creating drought stress as dull blue or purple sections. Further stress results in a tan or light brown lawn as the plant shuts down to preserve itself. Remember, grass blades are 99% water, so no water- no grass to grow!
Now is not the time to apply liquid fertilizer or herbicides- the result can be a disaster resulting in what I call “corner to corner grey or brown turf”. A trained eye can spot this kind of chemical induced stress. High soluble fertilizers place undue stress on a lawn already on the edge. Mowing during the heat of the day is like lying on your driveway at noon- hot and unpleasant. Any remaining moisture is quickly lost through the fresh cuts as the lawn literally wilts in hours- sometimes causing massive browning. Stressed turf is highly susceptible to mower tracks from the weight of a tractor. This is also true of lawn care companies that use perma-greens and other powered equipment to apply fertilizer, lime, or herbicides- the pure weight causes tire tracks and the resulting brown lines! A light touch using smaller spreaders helps to minimize this issue.
In short, high summer heat is not customary in NH or VT, but when it does occur- be sure to watch out for insect damage, water if you can- what you can, don’t mow if you don’t have to- especially during 11am to 3pm, and cut high 3” to 3.5”. Don’t feel obligated to mow when not mowing is really the best course of action.
Take a vacation and have some fun- but make sure you take care of your investment!