Mow the Grass Taller
Mow cool-season grasses at 3 to 4 inches and keep warm-season grasses 2 inches tall.
Longer grass blades have more surface for photosynthesis, promote deeper roots, and shade the soil. Keeping the grass taller during summer improves resilience to drought, stress, diseases, and pests.
Fertilize Warm-Season Grasses if Necessary
Apply a slow-release fertilizer from late May to early June if you have a warm-season Zoysia lawn. It provides the grass with valuable nutrients for the growing season.
Winter grasses fight drought and heat stress during summer and often enter semi-dormancy. Postpone fertilizing winter grasses, aka cool-season grasses, until August, when the weather cools down, rainfall gets serious, and cool-season grasses start to thrive again.
The Delaware Livable Lawns Program also recommends against using fertilizers between June 16 and August 14 to avoid leaching nitrogen and phosphorus into local bodies of water.
Irrigate Deeply and Less Often
lawn being watered
Photo Credit: ba11istic / Canva Pro / License
July is the hottest month of the year in Delaware. Temperatures can reach 88°F, and cool-season grasses are stressed and tend to enter semi-dormancy as a protective measure.
This often happens in the southern inland areas, around Seaford and Laurel, where the heat is more intense and dry. When the grass goes dormant, stop watering. It greens up again when the temperatures lower and rain begins to fall.
Proximity to water softens the heat in the northern coastal areas around Wilmington and Middletown. Here, temperatures are a few degrees lower, and winter grasses can stay green throughout most of the summer with proper watering. The grass also stays green and needs water on lawns with warm-season varieties, like Zoysia or Bermuda.
Ensure 1 to 1.5 inches of water per week, considering rainfall. Irrigate deeply, getting moisture 4 to 6 inches into the ground, and less often (once or twice a week if rain is scarce). Water early in the morning to prevent evaporation.
