Trees & Ravines

Why Hire an Arborist?

An arborist is a professional with knowledge of tree biology and physiology, and experience in arboriculture - the cultivation, management and study of individual trees. Learn when and how to hire one.

What is an arborist?

An arborist is a professional that is knowledgeable about tree biology and physiology and has experience in the practice of arboriculture, which is the cultivation, management and study of individual trees.

Why should I hire an arborist?

Tree work is very dangerous. It is recommended that you hire a company or person that knows how a tree should be maintained to ensure tree health and to address safety concerns. An arborist can also determine when a tree can no longer be maintained and should be removed due to health, structural concerns or safety and other reasons that may impact long-term viability. Tree removal around buildings, vehicles and wires presents special challenges.

What qualifications should an arborist have?

The tree care industry is not regulated. However, many arborists choose to become certified by the International Society of Arboriculture (ISA), a non-profit professional organization that supports tree care research and education around the world. The ISA provides the latest information and techniques to their members and certified arborists. In order to become certified, it is necessary to pass a written examination. To maintain certification, the arborist must keep current of innovations in the tree care industry through training and participation in educational seminars every year. Certification can attest to the tree knowledge of an individual and that they understand accepted practices. Certification cannot guarantee quality of performance; however, certified arborists are governed by the Certified Arborist Code of Ethics with the ISA. For more information about the International Society of Arboriculture, visit

What services can an arborist provide?

  • assessment of tree health and diagnosing insect and disease problems
  • treatment for pests/diseases
  • pruning – includes:
    • removal of branches that are dead, dying, infested by pests, diseased or damaged by storms
    • growth that interferes with other branches, wires, structures, traffic or pedestrians
    • efforts to improve tree structure, or restore crown balance
    • cabling/bracing procedures to reinforce a weak structure or branch attachment
  • fertilization
  • soil aeration
  • tree removal and stumping
  • tree planting
  • removal of tree debris

How can I find an arborist?

You can find tree care companies and arborists in the Yellow Pages, or similar business directories such as The Gold Book, under “Tree Services” or by location through the International Society of Arboriculture website: You should only hire a company that specializes in tree work and has the proper equipment. You want to ensure that you are getting quality work that will be performed in a safe manner and meets your expectations.

Before you hire a tree service company or arborist, we recommend you get two or three estimates. It is a good idea to get estimates in writing and to read the document carefully to see if the estimate includes all the work you would like them to perform, such as removal of all brush and wood, stump removal, etc. While not common, accidents – even fatal accidents – can happen while work is being performed. You need to know that the company and its workers are insured for any injuries or damage, so that you as a homeowner are protected from liability. Don’t automatically accept the lowest bid. You should also consider the credentials and written specifications for the job. You may also want to check references or look at other properties where the arborist has performed work.

What questions should I ask when hiring an arborist?

  • Do you have liability insurance, Workers Safety and Insurance Board (WSIB) coverage or equivalent? Liability insurance provides coverage for damages resulting from work and WSIB coverage or equivalent insurance provides for workers in the event of injury or death. Homeowner insurance may not cover contractors performing work on site.
  • Could I have a copy of the WSIB clearance certificate or equivalent insurance and the liability coverage once we decide to move forward with this work? Companies with proper coverage should be able to easily produce these documents.
  • Is your crew trained? Often qualified workers are trade recognized (i.e., they possess certificates from recognized colleges and/or trade associations such as the International Society of Arboriculture).
  • Will you use specialized equipment such as a bucket truck or crane? Do you own the equipment? If not, insurance certificates, both liability & WSIB or equivalent insurance should be produced for any subcontractor.
  • Are you a member of the International Society of Arboriculture, Ontario Commercial Arborist Association, Tree Care Industry Association, or the American Society of Consulting Arborists? These are professional associations that promote and provide continual training to workers and company owners on safe and efficient operations specific to the industry.
  • Is tree work your sole source of business?
  • How long have you been in this business?
  • Can you provide references?
  • Do you provide a written estimate?
  • Is there a charge for an estimate?
  • Does the estimate include the clean up and removal of all brush and wood?
  • If I would like more work done, what is your hourly rate?
  • When can the work be done and how long will it take?
  • Do I have to be home when the work is done?
  • What form of payment is accepted (cash, credit card, etc.) and when is payment due?

What things may influence price?

  • Proximity to fixed objects, or targets such as:
    • hydro lines
    • driveways
    • structures (houses, garage)
    • busy roadways
    • landscape features (fountain, gazebo, pool, etc.)

The closer and/or more significant the targets, the more complex the work becomes. This can increase costs.

  • Accessibility issues: for example, a tree located in the front yard has easier access and can take less time and equipment to remove than a tree in the back yard. Different equipment may be required depending on accessibility.
  • Material or debris left on your property will reduce time and/or equipment and can reduce costs.
  • Additional services such as stump removal and re-sodding can require additional visits to the site and increase costs.
  • Current state of tree structure: is the tree dead or alive? Is there any rot in the tree, or splits in the trunk/branch unions or branches? These details affect how difficult or unsafe the job is and can increase the cost.
  • Size: the larger the tree, the more work involved to remove it and the greater the cost.
  • Proximity: if a number of trees in the same area require removal, it may reduce the cost per tree.

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