City of Toronto: Toronto Water - Water efficiency

Tree and shrub care

Trees are different from lawns and garden plants

Unlike the roots on your lawn or in your flower garden, the majority of tree roots grow outward not downward. Approximately 90% of a tree’s roots are found in the top 12 to 18 cm (4½ — 7 inches) of soil and can extend out up to three times the height of the tree. These feeder roots must compete with grass and other plants for the water and oxygen they need for photosynthesis and growth.

The most important factor in growth rate and health of a tree is water. When it rains, most of the water runs off paved surfaces into the storm sewers never reaching the trees that desperately need it. Most trees (even large, mature ones) don’t get the water they need. If you notice leaf discolouration, deformation, wilting or loss, your tree may be experiencing severe drought.

Follow these tips to help your trees and shrubs grow tall and strong:

Tip

Don't over-water

It is possible to over-water trees as well. Ensure that there is no standing water under your tree. If the soil is sopping wet after watering, you may need to reduce the duration of time you water, or how often you water.

Tip

Mulch, mulch, mulch

Applying a mixture of woodchips, leaves and compost is one of the best things you can do for your tree’s health.

Spread mulch in a circle around your trees as far out as you are willing (the bigger the circle the better for the tree) but ensure that it is not more than 7.5 cm (3 inches) deep so that roots can still get oxygen. Keep mulch in a doughnut shape, making sure it does not touch the trunk to prevent moisture build up.

Tree Care — Six things to avoid

Lawn mower damage
Lawn mower damage is the #2 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.
Tying or attaching things to trees
Rope, string or wire tied around any part of a tree can cause serious damage. Trees grow a new layer of tissue every year and when this growth is restricted, the flow of water and nutrients up and down the tree is affected. Also, avoid nailing bird houses or other objects to trees as these create entry wounds for pests and disease.
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. Do not install paving or interlocking brick near trees, as you need to maintain a large area of soft ground surface around your tree so that roots can grow and will get the water and oxygen they need.
Salt
Salt applied to walkways, driveways and porches in winter eventually works its way into the ground. Try chopping away ice in winter and using sand as an alternative.
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 trunk is large enough to support it. Instead of high nitrogen fertilizers use compost.
Pesticides and 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. They have also been proven to be harmful to humans and pets. Always use non-toxic alternatives to chemical pesticides. For serious infestations contact an arborist to inquire about non-chemical methods of treatment.

Resources

Tree siting and selection

LEAF offers a backyard tree planting program within the city of Toronto. For details visit www.yourleaf.org or call 416-413-9244.

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 311.

Hiring an arborist

To locate a certified tree care professional in your area, contact the International Society of Arboriculture at www.isa-arbor.com or call 1-888-463-2316.

When it rains, most of the water runs off paved surfaces into the storm sewers never reaching the trees that desperately need it.

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