Tree Care Guide

Six Things to Avoid

1. Lawn Mower Damage

Lawn mower damage is the number two killer of young trees, second only to drought! Establish a wide circle of mulch to protect the base of you tree from mowers and weed-wackers.

2. Tying or Attaching Things to Trees

Rope, string or wire tied around any part of a tree can girdle the bark and cause serious damage. Trees grow a new layer of tissue every year. When this growth is restricted, the flow of water and nutrients up and down the tree is affected. Avoid nailing bird houses or other objects to trees, as these create entry wounds for pests and disease.

3. Root Damage

Tree roots are out of sight and often out of mind. Don’t forget that roots extend up to three times the height of the tree. Be sure to maintain a large area of soft ground surface around your tree so that roots can grow and get the water and oxygen they need. Do not install paving or interlocking brick near trees.

When doing renovation or construction in your yard, be sure to establish wide tree protection zones. Small grade changes, such as adding a few inches of soil for sod or grass seeding, can also damage trees by reducing their ability to absorb oxygen through their roots. Piling soil or other materials around the base of trees is a common mistake that can be fatal to trees. Root damage results in weak foliage and leaf loss, but may not become apparent for up to three years after the damage occurs.

4. Salt

Salt applied to walkways, driveways and porches in winter eventually works its way into the ground. The trees in you yard can be negatively affected during spring melt when they begin absorbing water. Try chopping away ice in winter and using sand as an alternative.

5. High Nitrogen Fertilizers

Fertilizing your lawn or garden will also affect your trees. High nitrogen fertilizers can cause a rapid increase in height before the diameter of the trunk is large enough to support it. Sprinkling compost is a more balanced and natural way of feeding your lawn and garden and will also be beneficial for your tree.

6. Pesticides & Herbicides

Trees often suffer “chemical burn” when pesticides or herbicides are applied to lawns. This can actually be fatal to trees. Chemical pesticides can also be fatal to beneficial insects, butterflies and songbirds, and have been proven to be harmful to humans and pets. Always use non-toxic alternatives to chemical pesticides. For serious infestations, contact an arborist. Inquire about non-chemical methods of treatment.

Following the care instructions in this factsheet should help you prevent problems. When in doubt, contact LEAF or consult an arborist before taking action.

Other resources

City Trees

To inquire about having a free tree planted in front of your home, or for questions related to city-owned trees, contact City of Toronto Forestry Services at www.toronto.ca/trees or call Toronto's information line at 311.

Hiring an Arborist

To locate a certified tree care professional in your area, contact the International Society of Arboriculture at www.isaontario.com or call 1.888.463.2316.