Many tree health issues can be resolved by following these general steps to improve their health. View our Tree Care Guide for Trees on Boulevards for helpful tips and more information on caring for your boulevard trees. They need all the care they can get, because trees on the City of Thunder Bay’s boulevards can encounter damaging or life-threatening conditions in our urban environment. These include:

  • Limited space;
  • Lack of sufficient water;
  • Poor soil conditions;
  • Human damage;
  • High ambient temperatures;
  • Drying conditions;
  • Air pollution;
  • Insects; and
  • Diseases


Lack of water is the single greatest factor that leads to the death of newly planted trees. The City of Thunder Bay waters newly planted trees at least weekly for the first year of growth, if not more. If you would like to help water more established trees, water during dry spells using a trickling water hose once a week to soak the root area for one to two hours. Avoid short, frequent watering that can create a shallow root system. Instead, infrequently soaking the ground deeply is preferable. We recommend water during the early morning hours. Water absorbing roots are located within the first 25 cm of the surface and extend outward well beyond the tree’s canopy. Make sure to respect the summer watering restrictions.


Mulch, which can consist of chipped wood and bark, shields the soil, retains moisture, prevents soil compaction and reduces lawnmower damage. Maintain a level grade of mulch that extends to the dripline (or further) around the tree to a depth of 5 to 10 cm. Do not mound mulch. Make sure to keep it a few centimetres away from the trunk to avoid rodents and other tree health complications. Spread the mulch beyond the tree’s canopy, to a distance away from the trunk that the branches extend.

Mulching both your public and private trees reduces the amount of lawn to maintain, while still looking nice and formal. This reduces your water, fertilizing, and appearance worries too! Go even further and consider a rain garden (with EcoSuperior Rebate) for your private property!


Please contact us to ensure that the tree has not been fertilized already. Choose tree fertilizer stakes to feed your tree. Apply these stakes into the ground as soon as the ground thaws in the spring, and water the tree throughout the growing season. This slowly releases nutrients to the tree’s roots. For fertilizer quantities, follow the directions on the label. Do not fertilize your tree in late summer; it will stimulate growth and prevent the tree from preparing for winter.


You can help by pruning new shoots, overhanging branches and broken branches on the boulevard tree next to your property as long as they are less than 40 milimetres or 1 ½ inches in diameter. Sucker shoots can be removed that grow from the bases of the trees, as can small damaged branches and small overhanging branches that get in the way of walking and parking. You must follow our proper pruning practices. 

Sucker shoots

New shoots, commonly referred to as sucker shoots, originating from the ground near the base of the tree. You can remove shoots with diameters up to 40 milimetres (1 ½ inch) that are located within 30 centimetres (12 inches) off the ground. Removed them as close to the ground as possible using hand pruners or loppers.

Overhanging or damaged branches

You are allowed to shorten damaged branches, branches that have been broken or that are hanging low over the ground to provide clearance for pedestrian traffic or vehicle parking. 

Overhead clearance

We require up to 3 metres (10 feet) of clearance above the road or sidewalk. You can only remove downward-growing branches smaller than 40 milimetres (1-1/2 inch) in diameter. Contact us if any branches need to be pruned that are growing higher than 3 metres (10 feet) above the road or sidewalk. Branches that are larger than 40 milimetre (1-1/2 inch) in diameter or branches that require removal at the trunk.

Pruning techniques and practices

You must adhere to the following standards.

 Cuts to shorten branches

a reduction cut on a tree branchReduction cuts

Use a a reduction cut to shorten a branch back to a lateral branch that is large enough to assume the terminal role. The lateral branch should be at least half the diameter of the removed portion. In the example to the right, the diameter of the removed branch is 40 mm and the diameter of an appropriately sized lateral branch should be between 13 and 20 mm.

Heading cuts

The correct angle of 45 degrees for a heading cutYou can use a heading cut on current year’s growth to reduce the length of a branch or sprout. Use a heading cut for shortening one-year old branches. Note that the location of the cut is angled and just to the outside of a lateral bud.


 Use the proper tools

Make sure to do all pruning from the ground using

  • hand pruners (secateurs);
  • loppers; and
  • pole pruners.

Your tools should be sharp in order to make clean cuts without jagged edges or stubs. Avoid anvil-type pruning tools with a blade that cuts to a flat surface because they crush tissue. Use tools with bypass (scissors-type) blades. Place the blade side of the pruner toward the tree and squeeze the blade up through or across the branch. Passing the blade down through the branch can cause the union to split.

Don't use saws, power tools and ladders

Use of any type of saw or power tool is not permitted and ladders are not to be erected on municipal property. 

Sterilize your tools

Properly sterilize your pruning tools between each use and each tree pruned to reduce chances of transmitting diseases. Spraying with isopropyl alcohol (rubbing alcohol) would suffice.

 Avoid wound dressings

Do not apply wound dressings to pruning cuts. Research shows that these products do not reduce the spread of decay. Proper pruning cuts assist a tree in using its own defences to close wounds and fight off decay.

 Birch, maple, and elm trees

  • Do not prune birch and maples trees until after the end of June to avoid excessive bleeding.
  • Do not prune elm trees from April 1 to August 1, which is the period during which the beetles that transmit Dutch elm disease are active.

Do not prune without approval

Contact us before you trim and let us know the extent of the pruning required. Do not prune without approval from the City. We will provide you with guidelines on proper pruning procedures and this also allows us to update our street tree inventory database.

What to avoid to promote tree health

  • Do not damage a tree in any way.
  • Do not mark, cut, debark, deface, break, injure or apply harmful or toxic substances.
  • Do not do any unnecessary excavating, grade changes, soil compaction, root cutting or hard surfacing around the trees, which can destroy vital roots.
  • Do not post any signs or attach objects to public trees as nailing or tying things can injure a tree and make it prone to insect and disease damage.

Do not dig

Do not dig under or around the tree to at least as far as the branches spread. This will damage the feeder roots required to provide nourishment for the tree and could allow pathogen entry or destabilize it.

Do not store or dump material under the tree

Do not store or dump material under the tree to at least as far as the branches spread. This material could be toxic or lead to soil compaction, depriving the tree of air and water. Refrain from using salt or herbicides around trees.

Do not destroy or remove a public tree

Do not destroy or remove a public tree – it constitutes an offence and there will be consequences. If you feel the tree is a hazard, contact City Dispatch at 807-625-2195 and let us know of any concerns and we will come and assess the tree.

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