Why heat is a problem for trees High temperatures have a detrimental effect on tree leaves and roots. Increased leaf temperatures cause trees to cool themselves through the process of transpiration. On a hot day, a large deciduous tree can transpire as much as 100 gallons of water into the surrounding air. This volume of water is not always available to trees on hot sites because of inadequate moisture in he soil. Scorched leaves on a flowering dogwood grown in full sun.
High temperatures can also adversely affect roots.
Loss of vital roots, and their uptake of water and dissolved nutrients, can result in tree death. Preparing hot sites for planting To help trees adjust to hot sites, preparation prior to tree planting is important. If large planting beds will be used, organic matter such as compost can be incorporated into the soil to improve soil structure, air movement and water retention. 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.