Media Release

Heat wave putting Toronto trees at risk

Watering a newly planted tree


Residents and businesses urged to help by watering trees

(June 20, 2012) This week’s extreme heat is putting urban trees under stress and at risk due to drought, says urban forest advocates at LEAF (Local Enhancement & Appreciation of Forests).  They are calling on residents to help the trees that shade their homes and neighbourhoods by giving them a much needed drink of water!


“Urban trees offer great benefits during the hot summer months, reducing the need for air conditioning and lessening the strain on our electric grid.  Unfortunately, due to increased levels of stress, they are much more vulnerable than they appear,” says Janet McKay, Executive Director, LEAF. “Often by the time the effects of drought become noticeable, it’s too late."


Toronto’s urban forest acts as a natural cooling system, providing shade and naturally cooling the surrounding air.  Larger trees can discharge up to 375 litres of water per day as their roots draw water up from the soil and through each leaf surface.  Without a healthy supply of water this process, called evapotranspiration, cannot take place.  Trees become stressed and suffer increased vulnerability to attacks from pests and disease, which undermines the cooling and smog-reducing effects our city so desperately needs.


“A simple way to help keep our urban forest healthy is watering trees in the early morning or evening” said McKay. “Using a low flow hose helps to ensure that water soaks into the soil rather than running off onto driveways, sidewalks or streets away from where the tree can use it.”


“Street trees are particularly vulnerable due to challenging growing conditions such as in the small soil volumes in raised planter boxes,” continued McKay. “Businesses can help by watering the trees in front of their store and by encouraging others to do the same.”   


Young trees planted less than five years ago, should be watered with 20 litres of water twice per week, the equivalent of two or three large buckets.  Mature trees should be watered with a soaker-hose or regular garden hose.  Water should be allowed to flow slowly from the hose for up to an hour once or twice a week.  The hose should be moved around periodically to ensure the whole area under the tree's canopy gets a good amount of water. Sprinklers should be avoided as they waste water through evaporation and lead to sun scalding on the leaves of trees and shrubs. For more tree information on proper tree care, or information on how you can get involved in your community visit,                                                                                                                              


“Everyone can help protect this shared resource by getting out there and watering the trees around their homes and in their neighbourhoods,” concluded McKay. “The benefits will not only keep our city green, but give relief to all residents who are dealing with this intense heat.”



For more information contact:




Kyle Ferguson, Manager, Marketing and Communications, LEAF  

416-413-9244 x 16 (w) 416-819-5631 (c) | 


LEAF is an incorporated, not-for-profit organization dedicated to the protection and improvement of the urban forest. LEAF engages citizens in urban forest stewardship through planting, education and training. Since 1996, LEAF has helped residents plant more than 17,000 trees and shrubs. For more information, or to get involved, visit 




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