Tips for Summertime Lawn Care

The hot, dry, late summer months can be stressful on lawns. Lawns throughout the Midwest and Great Lakes regions are generally comprised of cool season grass varieties such as fescue, ryegrass, and bluegrass. While these varieties are adapted to surviving cold winters and thrive in cooler spring and fall conditions, they can struggle to maintain the desired appearance during the hottest times of the year. Here are a few tips to keep your lawn looking its best.

Fertility – A properly fertilized lawn is better able to withstand the stress of hot, dry weather even though it may still turn brown. The difference is that a nutrient deficient lawn is more likely to die under heat stress, where a healthy lawn may go dormant and quickly rebound when conditions improve. However, once a lawn has gone brown, fertilizer applications will not fix the problem if the weather is still not fit.

Nitrogen – Most lawn care programs will recommend nitrogen targeting about 4 pounds of nitrogen per 1000 square feet split into 3 or more applications throughout the growing season. Fertilizer products formulated for lawn use are generally treated to slow the release of nitrogen and may contain some potassium and traces of other nutrients such as sulfur and iron. This is a great start since grass responds well to nitrogen, but they generally do not address all the fertility needs of a healthy lawn.

Phosphorus and Potassium – P and K both play several important roles in plants. The most important roles for promoting a healthy lawn are that P stimulates root growth and transports energy and K regulates water movement within the plant. Residential lawns are often deficient in P and K since the soil used to construct the lawn is usually subsoil left from the construction of the house. A routine soil test will indicate if P and/or K fertilization is needed. Lawns should have a Bray P1 around 25 to 40 ppm and K around 150-200 ppm. If P and K are needed, the recommended amounts should be applied in the spring and/or fall when temperatures are cooler and soil moisture tends to be higher as these are generally fertilizer products with a high salt index that have the potential to cause damage to growing plants if they are stressed. Once desirable levels of P and K are reached, if the clippings are not removed from the lawn, little or no additional P and K are needed to maintain the levels.

pH – Management of the pH is critical for assuring nutrient availability. A routine soil test will indicate if the pH needs adjusted. Lawns perform well in a pH range of 6.3 to 7.3. If the pH is lower (acidic) it can be easily corrected with lime. Alkaline (high pH) soils are common due to the subsoils that make up many yards. High pH is much harder to correct but can be done through repeat applications of elemental sulfur in the spring and fall, but it may take 2 or more years before a noticeable change happens.

Aeration – One of the challenges with hot, dry conditions is that the soil is generally hard and crusted and what little precipitation there is often comes in short, intense events that quickly runoff or evaporate before the moisture can soak into the root zone. Having a will aerated lawn will help to improve water infiltration and utilization.

Irrigation – Irrigation certainly has the potential to minimize the effects of the stressful summer heat, but it is important to make sure that the water being used is not causing any additional problems. Most well and municipal sources of water will have a high pH. Continuous use of alkaline water can cause nutrient tie-up in the soil. Avoid using softened water. Softened water, from conventional treatment systems, will contain sodium which at high levels can be toxic to plants and destroy soil structure. Irrigation systems are generally plumbed separately from the interior plumbing to avoid this, but if using an outdoor spigot to run a sprinkler, this water may be softened. If so, bypass the softener while irrigating.

The key thing to remember to keep your yard looking its best is that most lawn care services do not address the P, K, or pH needs of your lawn. They generally apply only nitrogen fertilizer and insecticide and herbicides when needed. A lawn can look very good with frequent nitrogen applications but can quickly fail when stressed. Managing the other aspects of the lawn are generally up to the homeowner.