Preventing drought stress in lawns

Maintaining a healthy lawn during the heat of the summer can be challenging for even the best of gardeners. High temperatures and limited rainfall can quickly lead to drought stress — causing grass to wilt, discolor, and become brittle. Lawns, like all plants, require a constant supply of water to perform their life functions.

Lawns in southern Idaho can be composed of either cool-season or warm-season grasses, each with distinct characteristics, growth habits and seasonal preferences. Cool-season grasses like Kentucky bluegrass, tall fescue, and perennial ryegrass thrive in temperatures between 60-75°F. They grow actively during the cooler months of spring and fall but may go dormant or suffer during the heat of the summer. Warm-season grasses like Bermuda grass, buffalo grass, and zoysia grass thrive in temperatures between 80-95°. They grow rapidly during the warm months of late spring through early fall and go dormant in cooler temperatures. While in some states, Bermuda grass is classified as a noxious weed because of its aggressive growth, it is not considered noxious in Idaho. Proper management practices are important to keep it under control and ensure it does not become problematic.

Several drought-tolerant grasses can be successfully used to create resilient and low-maintenance lawns. These grasses are adapted to thrive with less water and can withstand periods of drought. Tall fescue is a coarse-textured, deep-rooted grass that is well known for its excellent drought tolerance. It performs in both sun and partial shade and is suitable for lawns. Fine fescue is a fine-textured, highly drought-tolerant grass. It is ideal for shady areas and low-maintenance lawn, with good drought tolerance once established. Perennial ryegrass is a fast-germinating, fine-textured grass that can handle moderate drought conditions. It is best used in mixtures with other drought-tolerant grasses to enhance resilience.

To maintain a healthy lawn, it is crucial to irrigate deeply and infrequently, considering the soil texture. For example, sandy soils, which require 1.25 to 1.5 inches of water per week, drain quickly and benefit from more frequent, deeper watering sessions to ensure moisture reaches the root zone. In contrast, clay soils, which need only 0.5 inches of water perf week, retain moisture well but drain poorly, making it essential to water less frequently to avoid waterlogging. Loamy soils, with a balanced texture and needing around 0.75 inches of water per week, strike an ideal balance and can be watered deeply once a week. By adjusting watering practices to match the soil’s ability to retain and drain water, lawns can develop deeper root systems, making them more resilient to drought and reducing the overall frequency of irrigation needed.

Improving soil structure and organic matter also increases grasses’ ability to withstand drought stress. Soil structure can be improved though the use of aeration during times of the year when the grass can recover quickly. With cool season grasses you should aerate in the early spring or late fall. One simple way to improve organic matter is to leave the lawn clippings on the lawn after mowing. These clippings left on the lawn decompose and add organic matter to the soil.

Raising the mower height is also a good practice to reduce drought stress. Lawns should be mowed 3-4 inches in height. The longer blades of grass have a larger surface area for photosynthesis and promote deeper root growth as the plant invests more energy into the root system. Taller grass can shade out weeds, preventing their establishment. The shade also keeps water in the soil.

In conclusion, maintaining a healthy lawn during the summer heat requires a combination of strategic practices tailored to the specific needs of your soil and grass type. Selection of drought tolerant species and implementing proper irrigation and mowing techniques can improve a lawn’s ability to resist drought conditions during the summer months.