We are nearing the peak of summer and the weather can take a toll on your trees and shrubs. Extended periods of heat and humidity, along with bright sunshine, warm nights, and inadequate rainfall can stress your landscape.
Trees and shrubs are constantly losing water through tiny holes in their leaves; a process called transpiration. When it's hot, the rate of water loss increases. Add to that a lack of adequate rainfall and the result is often stressed landscape plants. Trees do not have the luxury of going dormant in hot summer months like most turf grasses. Instead, trees have active leaves through which they lose a lot of water. Their roots look for water in the soil; however, due to the summer heat there is less of a water supply to replenish the trees nutrients.
Trees suffering from heat stress face problems with producing new growth, healing wounds, and fighting against diseases and insects. If they're stressed enough, they eventually run out of energy to support their existing growth and begin to decline (sometimes irreversibly). Newly planted (within the last 2 years) and mature trees (30-50 years depending on the species) are the most at risk for serious decline; we've seen both this summer. Trees that are more prone to heat stress and drought include Birches, American Dogwoods and Japanese Maples.
So what's the solution? The best way to combat heat stress is through a combination of proper irrigation, mulching and proper plant health care.
Proper irrigation means saturating the root zone of a tree. Sprinklers work for lawns, but they don't get the job done for trees. A properly placed soaker hose, running along the ground under the canopy of a tree, is a great choice. Trees have a deep root system requiring a slow feed of water to irrigate the thick soil. You can use a traditional garden hose, by setting the flow to a trickle and moving the mouth of the hose around, to four or five different areas of the root zone over the course of the day. Newly planted trees, which run a high risk of suffering heat stress, should be watered 2-3 times a week depending on the amount of rainfall; set the nozzle on a hose to a very slow shower for a time no less than 10 minutes.
A good line of defense against hot weather conditions is a layer of mulch around trees and plants. Mulch reduces evaporation of water from the soil and provides a more consistent soil temperature that is ideal for root growth. However, to be effective, mulch needs to be applied correctly. We recommend a depth of 2-3 inches of mulch that covers a diameter that extends to the tree's leaf canopy edge and doesn't pile up against the stem of the plant. If you have any questions about mulching, please feel free to speak to an ArborTech Arborist.
Plant Health Care
It is important to be pro-active with your landscape trees and shrubs. ArborTech's Plant Health Care (PHC) program is designed to monitor and treat your plants to avoid damage/stress caused from pest, pathogens, nutrient deficiency & physical injury, which if not prevented, makes trees more susceptible to damage from the summer's heat and drought conditions.
The summer months can be a tough time for all living things. But unlike most creatures, trees can't get up and move to a cooler location. By following the tips above, your landscape plants will have a better chance to beat the heat.