There is nothing more relaxing then being able to cool off under the shade of a tree in the middle of summer, but we also need to consider what kind of care we should be providing our trees during the summer.
“Once established, trees can be very tolerant of environmental stresses, but in the heat of the summer, especially when there is a lack of rain, they can struggle and need additional irrigation to reduce stress,” explained University of Illinois Extension horticulture educator Kari Houle.
“Even established trees have the potential to lose large amounts of water during the heat of the summer. An old saying is that a 90-foot-tall and wide tree can lose up to 100 gallons of water in a day,” she said.
To help reduce stress on established trees during the heat of the summer, provide supplemental irrigation if there has not been rainfall during the previous two weeks. Most turf irrigation systems are unable to provide necessary supplemental irrigation for trees because most systems do not run long enough to make a difference or run at a rate faster than the soil can absorb the water.
“Drill multiple small holes in the bases of large clean garbage cans or five gallon buckets. Set these containers out around the root system of the tree. Fill them with water and then move and refill. This provides a slow release of water and allows it to be absorbed into the ground. Other options include drip irrigation, soaker hoses, or sprinklers,” Houle explained.
According to Houle, trees need between 1 to 2 inches of water every two weeks. Water-loving trees such as birch, pin oaks, and tuliptrees may need up to 3 inches per week when temperatures are above 90 degrees.
To assist in reducing moisture loss, make sure that trees are mulched. Mulch helps maintain moisture and helps assist in temperature regulation of soil. Organically derived mulches such as shredded hardwood or cypress provide the best benefits, Houle explained. Inorganic mulches such as rock are not recommended.
“If possible, mulch out to the drip line of the tree and spread the mulch 2 to 4 inches deep, keeping it a few inches away from the trunk of the tree. Mulch also prevents damage from lawn mowers and weed whips by keeping them away from the trunk of the tree,” she added.
Houle also recommends avoiding pruning during the summer to minimize the chance of spreading diseases such as fireblight or oak wilt. “The best time to prune trees is when they are dormant as it minimizes the spread of disease, and it’s easier to see the structure of the tree,” she explained. “Don’t hesitate to contact a certified arborist to prune your tree or inspect and prune if damaged in summer storms.”
Material provided by University of Illinois College of Agricultural, Consumer and Environmental Sciences