Hot weather can create stress for lawn grass much as it does for human beings. Fertilizer stimulates the grass to grow but can also chemically burn the blades if applied improperly. According to Michigan State University, late summer and early fall are the best times to fertilize your lawn, but in many areas of the country these times can represent some of the warmest weather of the year. Using a few strategies to limit stress on the grass will help you safely apply fertilizer to your lawn in hot weather.
Fertilize your lawn on a day where temperatures remain below 85 degrees Fahrenheit and conditions are slightly overcast. Alternatively, apply the fertilizer in the early morning hours when the sun is not yet fully up and temperatures are at their coolest.
Use slow-release fertilizer formulations for the most gentle impact on the grass and little to no threat of chemical burn. Use quick-release products at a rate under the label recommended dosage for your acreage, to limit chances of burn.
Water the fertilizer in thoroughly immediately after application. Soak the grass and surface soil so that the top 6 inches of soil is wet but water is not pooling on the soil. This will wash the fertilizer grains down to the root zone and further prevent burning of the green blades.