How to Recognize and Treat Heat Stress in Trees This Summer

Summer can be a challenging time for trees—especially during prolonged heatwaves and dry spells. Without enough water, trees can suffer from drought and heat stress, which impacts their overall health, growth, and resilience.

In this guide, we’ll walk you through the key signs of heat stress in trees, how to support recovery, and when to call in a certified arborist. Whether you're caring for mature trees or recently planted saplings, these strategies will help keep your landscape thriving all summer long.

What Is Heat Stress in Trees?

Heat stress occurs when a tree cannot absorb enough water to meet its needs during hot, dry conditions. This is especially common in the peak summer months when temperatures rise and rainfall is scarce. Young and newly planted trees are the most vulnerable to drought stress, but mature trees can also suffer if conditions persist.

Common Signs of Drought Stress in Trees

Spotting heat or drought stress early can make a big difference in how quickly your tree recovers. Watch for these key symptoms:

• Wilting Leaves: Leaves may droop, curl, or look limp—especially during the hottest part of the day.

• Leaf Discolouration: Leaves can turn yellow or brown and may show scorched edges.

• Reduced Growth: Smaller-than-usual leaves, sparse canopy, or slowed overall growth.

• Leaf Drop: Premature shedding of leaves as the tree tries to conserve moisture.

• Early Fall Colour: Leaves turning red, orange, or yellow long before autumn is a major sign of drought stress.
  

How to Help Trees Recover from Heat Stress

Supporting your trees during heat stress can prevent long-term damage. Here are six effective ways to treat heat-stressed trees and promote recovery:

1. Deep Watering

• Water slowly and deeply to encourage deep root growth.

• Focus on the root zone, which extends as far as the tree’s canopy.

• Water in the early morning or late evening to reduce evaporation.

2. Mulching

• Apply 2–4 inches of organic mulch (like wood chips or bark) around the base of the tree.

• Keep mulch a few inches away from the trunk to prevent rot.

• Mulch helps retain soil moisture and regulate root temperature.

3. Pruning

• Remove any dead, damaged, or diseased branches to reduce the tree’s stress load.

• Avoid heavy pruning during extreme drought conditions, as this can further weaken the tree.

4. Improve Soil Health

• Mix compost or organic matter into the soil to boost its water-holding capacity.

• Avoid fertilizing during droughts—added nutrients can over-stimulate growth and stress the tree further.

5. Monitor for Pests and Disease

• Heat-stressed trees are more vulnerable to insects and fungal infections.

• Check for signs of infestation (chewed leaves, fungal growth, sap leaks) and treat promptly.

6. Keep Monitoring

• Continue observing your trees throughout the summer.

• Adjust watering schedules based on weather and visible stress signs.

• Some trees may need extra care until cooler weather returns.

  
  

When to Call an Arborist

Some signs of heat stress go beyond what homeowners can manage alone. It’s time to call an arborist if you notice:

• Significant dieback of branches

• Widespread leaf loss or browning

• Fungal growth or insect infestation

• Structural concerns or signs of decay

Get Expert Help from TreeArb

At TreeArb, our certified arborists specialize in diagnosing and treating heat-stressed trees. We’ll assess your tree’s health and create a custom treatment plan to support recovery and prevent long-term damage.

Need help with a stressed tree? Contact TreeArb today to schedule your tree health assessment or learn more about our summer tree care services.