Incorporation of organic matter into the backfill soil for individual planting holes is not recommended. Installation of an irrigation system may be beneficial because irrigation can supply water for transpirational cooling. Selecting trees for hot sites Trees that are genetically capable of tolerating high temperatures should be selected for hot sites. Some species of trees are naturally heat-resistant, and many cultivars are available that have been developed for their ability to withstand high temperatures. Consideration should be given to site moisture levels because some trees can withstand heat only when adequate moisture is available.
Irrigation can be critical.
Mulching is also very important. Mulching will help keep the soil surrounding the roots cooler, prevent moisture evaporation and water runoff, minimize competing weed growth, and reduce the amount of light and heat that reflects onto leaf and stem surfaces. Fertilize trees in hot sites only as needed. Nitrogen causes trees to grow quickly, and an extra flush of new leaves may wilt and die due to heat stress. Do soil testing and observe plant health to determine if and when supplemental fertilization is needed.