When temperatures soar and rain disappears, your lawn often shows the first signs of struggle—fading color, patchy browning, and thinning grass. But not all damage is permanent, and not all of it is disease-related. Understanding what’s happening to your turf during periods of extreme heat and recognizing symptoms of blight can help set realistic expectations and guide proper care.
What Happens to Grass During Heat Stress?
From an agronomic perspective, heat stress isn’t just about the temperature outside—it’s about how the turfgrass plant responds internally. Cool-season grasses, like those common in Indiana lawns, have a preferred temperature range of 60–75°F. When daytime highs consistently exceed this range, the grass undergoes several changes to conserve energy and water:
- Dormancy: Grass may go into a state of dormancy, halting active growth and turning brown to preserve vital resources.
- Stomatal Closure: Tiny pores on grass blades, called stomata, close to prevent water loss. This also limits the plant’s ability to photosynthesize.
- Root Growth Slows: The plant diverts its energy away from growth to survival. Shallow roots become even more vulnerable during droughts.
Despite how rough it may look, this dormancy is a natural and reversible process—as long as the lawn isn’t pushed too far.
What Is Blight and How Is It Different?
Blight refers to a group of fungal diseases that cause grass blades to turn brown, collapse, and die. The most common summer blight is Ascochyta leaf blight, often mistaken for drought damage. Blight tends to:
- Appear suddenly and spread quickly.
- Cause patchy, straw-colored spots across the lawn.
- Be more severe on stressed or scalped turf.
Blight thrives under hot, humid conditions, especially after a stretch of rain followed by intense sun. While fungicides are available, they are not always necessary or effective—especially since the damage is mostly cosmetic and lawns often recover once the stress subsides.
What You Can Do to Help
While there’s no silver bullet to prevent heat stress or blight, you can take steps to support your lawn’s health and recovery:
Water Smart
Even if you can’t water the full lawn with the ideal 1–1.5 inches per week, some water during hot, dry stretches helps prevent irreversible damage. Aim to:
- Water deeply but infrequently.
- Water early in the morning (between 5–9 AM).
- Avoid light, daily sprinkling, which encourages shallow roots.
Mow High
Raise mower blades to 3.5–4 inches. Taller grass shades the soil, reduces moisture loss, and supports a healthier root system.
Reduce Stress
Minimize foot traffic and avoid mowing during peak heat. Extra pressure on already stressed turf can delay recovery.
Be Patient
Not every brown patch needs treatment. Many lawns bounce back once cooler weather and regular rainfall return. However, if large areas don’t improve in the fall, Brooklawn can assist with seeding and recovery.
Brooklawn is Here to Help
Heat stress and blight are part of the natural rhythm of summer lawn care. While they can be unsightly, understanding the difference between dormancy, disease, and permanent damage can help you make smart choices for your lawn’s long-term health.
Brooklawn Services continues routine fertilization and weed control during summer stress periods to support root health—and we’re always monitoring conditions so we can help guide recovery when the time is right. If you have questions about your lawn, please give us a call at 888-794-9555!
