If you’ve noticed Ottawa’s intense heat and humidity this summer, so have your trees. It’s important to protect your trees in summer as you would in winter because of heat-related issues such as heat stress. Heat stress will affect your trees in many ways – it makes them wilt, it stunts healing, and they are prone to further complications. Keep reading if you’re interested in summer tree care tips!

Protect your trees from heat stress

Threats of Heat Stress 

Every tree is different, but too much heat will affect them all the same. Trees that are young, old, diseased, or poorly planted saplings, however, will demand more tree maintenance. Your trees and saplings will start to experience heat stress when soil temperatures reach 34°C and photosynthesis stops. Depending on a variety of factors such as age, species, and water tissue content, the thermal death threshold for trees is 46°C. These temperatures are dangerous because the heat forces trees to expend water faster than it can replace it.

Identifying Heat Stress in Trees 

Heat stress will deprive your trees of water and other nutrients. You may be able to identify a threatened tree by looking out for these symptoms:

  • Wilting leaves and branches
  • Discolouration of leaves beneath the canopy
  • Sap seeping from the trunk (Careful, this attracts pests!)
  • Leaves that fall and are unable to be replaced
  • Inhibited root growth
  • Rust coloured spotting on leaves

It is important to note that heat stress will induce symptoms which are similar to other heat and water-related issues such as infections or drought. For this reason, we recommend you contact a certified arborist to determine the cause of your trees’ problems. 

3 Summer Tree Care Tips


Aside from watering, there are many appropriate treatments for heat-stressed trees. If you’ve successfully identified the presence of heat stress, these tree maintenance tips are sure to help with recovery and will promote future growth. 

  • Mulching: Mulch will retain water, assist oxygen flow, and maintain healthy soil temperatures. Contact a certified arborist to make sure you have the appropriate mulch for exceptional summer tree care.
  • Arbours and trellises: Use wood to protect your wood! A well designed and crafted arbour or trellis will mitigate the heat that hits your trees. These structures provide active shade without stunting growth. 
  • Avoid nitrogen-based fertilizers: Spreading nitrogen fertilizers on your trees in extreme heat will cause serious damage. These fertilizers promote rapid growth. A heat stressed tree will be expending all of its energy on survival; growth will do nothing but harm your trees. Also, the salt content in fertilizers will steal water that the tree needs to heal!

Protect Your Trees with Ottawa’s Trusted Tree Care Experts

Contact Croft Tree Experts if you suspect your trees are suffering from heat stress. Our combined 65 years of experience will ensure that your trees are taken care of with professionalism and expertise. We are happy to offer a free, no obligation estimate for our services after an inspection of your property has been completed. Contact us now to protect your trees from Ottawa’s intense summer heat.