How To Reduce Heat Stress On Seattle Trees

Seattle natives cherish their trees. From iconic Douglas firs to majestic maples, Seattle’s urban tree canopy is a vital part of the city. Yet, as summers grow hotter and drier, trees become more susceptible to heat stress. It’s essential to take proactive measures to help your trees beat the heat and ensure Seattle stays lush and green.

During the summer, trees can suffer from dehydration, weakened health, and increased susceptibility to pests and diseases. Providing them with consistent and proper tree care during the dry season is crucial.

What Are the Long-Term Impacts of Heat Stress on Trees?

When trees experience high temperatures without sufficient water, they eventually reach a point where they can’t take up enough water from the soil to support the whole tree canopy. During this time, the tree closes stomata on the leaves, which results in reduced photosynthesis and slowed growth. This can weaken the tree and make it susceptible to pests and diseases.

Here are common symptoms of heat stress to look out for:

• Curling or wilting leaves

• Scorched leaves

• Lead drop or a thinning canopy

• Dying branches

• Increased susceptibility to wood-boring insects

• Discoloration of conifer tree needles

The most effective way to prevent heat stress in trees is through preventative maintenance, like deep watering, proper mulching, pruning, and applying humates and phosphites.

Should I Water My Trees During a Heatwave

The main tip for watering trees during dry weather is to water deeply and infrequently. A soaker hose or drip irrigation system allows water to penetrate deeply into the soil without runoff while maintaining control of the water’s flow.

Watering early in the morning reduces evaporation losses and ensures trees have ample moisture to face the day’s heat. While it seems like the best course of action is to water more often, aiming for a thorough soaking once or twice a week encourages deeper root growth, making trees more resilient to drought.

Summer Tree Mulching Tips

Mulching is another critical technique to help trees retain moisture. A layer of mulch, such as wood chips or bark, applied around the base of the tree can help significantly reduce water evaporation, moderate soil temperature, and improve soil health.

Here are some of our tree mulching tips:

• Proper Application – Spread mulch in a 3-4 inch layer, extending to the tree’s drip line

• Avoid Volcano Mulching – Don’t pile mulch in a volcano form against the trunk. This can cause rot and pest problems. Instead, leave a 1-inch space between the mulch and the trunk

• Refresh Regularly – Replenish as much as needed, at least annually if necessary after heavy rains or wind. 

How to Protect Trees From Heat Stress

While mulching and watering are the main methods of reducing heat stress, trees can benefit from extra care during unexpected heat waves. Here are our suggestions on how to protect trees from heat stress:

• Humates – Humates improve microbial activity and nutrient absorption for your trees. They also improve water distribution and retention so the soil can hold more water. Humate products may also include wetting agents and micronutrients to boost these benefits

• Phosphites – Phosphites simulate a tree’s natural defenses against heat and drought stress, helping them to conserve water. Phosphite products include potassium, which also helps trees to maintain moisture uptake and manage stress.

• Tree Pruning – Pruning dead limbs and overgrown canopies can help reduce the overall amount of water a tree needs. Tree trimming also improves overall health.

• Temporary Shade – Shade cloths can provide temporary relief from direct sunlight for young or newly planted trees.

Should I Hire A Professional Certified Arborist for Heat Stressed Trees?

Professional certified arborists are trained to handle a variety of tree issues, including heat stress. Once on your property, arborists can do a proper assessment to tell you what your tree needs, help you retain the value of your home investment, and provide just enough care to give your tree the boost it needs.

At The Davey Tree Expert Company, we have ISA Certified Arborists located in Redmond, Lake Forest Park, Tacoma, and the surrounding areas to help you with your dry-season and watering maintenance.

CONTACT YOUR LOCAL SEATTLE DAVEY OFFICE FOR A FREE CONSULTATION