State of Arborist Companies in Ontario — Fall 2026

Key findings

• The industry is made up of 485 tree service and tree consulting companies across Ontario.
• Tree service companies outnumber consulting firms 28 to 1 (468 vs 17).

• A big gap between what ISA reports and what anyone can confirm. ISA Ontario says there are over 1,700 ISA Certified Arborists in Ontario. While many of them may work for municipalities or electrical authorities, we could confirm only 149 of them (about 9%) work in the private sector.
• More than a third (183 companies or 37.7%) say on their website that they employ an ISA Certified Arborist. So far we’ve been able to confirm a Certified Arborist on staff at 101 companies (20.8%).
• Board Certified Master Arborists are rare: 13 confirmed across all 485 companies, 5 of them at consulting firms.
• 38% (185) have a WSIB clearance certificate that we could confirm as present and active.

Where did we get the numbers?

We have acquired these numbers through multiple means, including:

• Google Business Profiles
• Companies’ own websites
• The WSIB clearance directory
• The ISA credential directory

Arborist certification

Only 101 of 485 companies (20.8%) have a staff member we could confirm in the International Society of Arboriculture’s (ISA) public credential directory. Nearly twice as many (183, 37.7%) say on their website that they employ an ISA Certified Arborist.

Case in point, see the picture below. On a company’s FAQ page, they state that all their arborists are certified. And yet, nowhere on the website can a single arborist be named whereby the public can fact check it.

The company may very well have a Certified Arborist, but we have no way of verifying it if the company doesn’t provide a full name of the individual.

In the case with this above company, we listed them as having 0 Certified Arborists.

Some companies will outright throw the ISA Certified Arborist logo onto their website and never back it up with any names or badge numbers.

One other related point. Many companies, when they state that they have Certified Arborists, ensure that they add an “s” at the end of the word “arborist”. Once again, that may be true but we cannot verify it. It is quite likely that at least a few companies make the word arborist plural to make them sound more competent.

The confirmation gap

ISA Ontario says the province has over 1,700 ISA Certified Arborists, but we could tie only about 9% of them to an Ontario tree company.

And yet, according to research by our database, we have only been able to identify 149 credentialed arborists: 135 Certified Arborists plus 14 Board Certified Master Arborists. On average, that works out to one confirmed Certified Arborist for every 109,000 Ontarians. For a city like Cambridge, Ontario, with about 140,000 people, that means only one or two confirmed Certified Arborists across the whole city to care for its hundreds of thousands of privately owned trees.

The confirmed figure is a floor, not a census. It can only count people who have listed their FULL name (first and last name) on a company’s website and who appear in ISA’s directory:

We believe the real numbers are MUCH higher, but once again, we cannot confirm it, because individuals, companies, and the ISA itself have not made it easy to pinpoint who is an ISA credentialed arborist.

Lead-generation sites posing as tree companies

At least 14 websites presenting themselves as Ontario tree companies turned out to be lead-generation websites, not companies with their own crews.

While technically this is a commonly accepted practice, some of these websites can be misleading. Oftentimes they suggest that they employ trained arborists to complete the work when that isn’t true. Only a few state (hidden somewhere in small letters) that they are not a tree service company.

How to spot lead generation sites: Common signs are a city name in the web address (“tree service [town]”), no street address, no owner or arborist named, and listing multiple different towns with a unique phone number for each.

We have intentionally excluded these companies from our database.

Ontario’s own arborist credentials can’t be checked

Ontario also offers arborist qualifications through an apprenticeship program. Skilled Trades Ontario issues a Certificate of Qualification in two trades: Arborist (444A) and Utility Arborist (444B). Each takes about three years: roughly 6,000 hours of on-the-job work plus in-school training, then a certifying exam.

These are serious credentials, but this report can’t count them. Both trades are non-compulsory, so, in Skilled Trades Ontario’s words, holders’ information “will not appear on the Skilled Trades Ontario Public Register.” There is no public list of who holds a 444A or 444B, or which company they work for. A company can say its staff are certified, but neither we nor a homeowner can confirm it independently. The figures above therefore cover ISA credentials only, and the real share of qualified arborists in Ontario is likely higher.

We would have liked to include the numbers of 444A and 444B arborists, but we simply don’t have access to them.

WSIB coverage

38% of companies (185 of 485) have a valid WSIB clearance certificate, which confirms their workplace insurance account is in good standing.

To summarize, there are 3 dozen companies that are “not eligible” for WSIB. This often means that they have not reported their “insured earnings” for that quarter and likely have not paid for them either.

This doesn’t mean that a worker who gets injured while working for this company will not be covered for that injury. BUT, it does signal whether a company is trying to be compliant and therefore trustworthy.

Also note that there are 263 companies “not found.” This means that no account matched the company’s trade, owner or legal name, which doesn’t prove the company lacks coverage.

It should be noted that ALL WSIB certificates expire November 19th. We will re-sweep all WSIB accounts at that point to re-verify.

In summary

We believe that the numbers reported are far understated.

Particularly when it comes to Certified Arborists and similar credentials. This requires a concerted effort from individuals, company owners, and the ISA to ensure credentials are appropriately accounted for.

As a very important aside, it is strongly encouraged that every ISA credentialed arborist update their profile completely so that their information can be quickly accessed.

From conversations with other arborists, there has been much talk about the recently re-vamped ISA Directory being difficult to work with. For example, at the time of writing this, if the person’s name is not an EXACT match to what is written in the directory (ie. Robert D. Smith), then it will likely not return results. Some individuals have also voiced challenges simply logging in to update their profile.

A very small percentage of arborists have accurately updated their credentials. Most arborists in our directory list are there because we pulled the name from the company website and matched it to the ISA directory.

The reverse would be a far superior option, which is, a company should be able to be looked up, and from there the credential holders in that company can be found. That cannot be done until individuals take up the mantle to update their profile.

Possible topics for future conversations

• Are there other certifications that should be included in this report? Most notably Registered Consulting Arborists with ASCA.
• The who, what, where, when, and why of private tree bylaws.
• And more (workplace injuries, provincial acts pertaining to arboriculture, updates to credentials, etc.)

Methodology and caveats

Figures come from the ArborProof directory database as of October 12, 2026. It covers 485 tree service companies and arborist consultants found across 31 Ontario regions between September 8 and October 12, 2026.

• Companies vs listings. Company totals count each business once. The directory has 509 office listings, even though they are spread between 485 tree services.
• WSIB. Each company was searched on WSIB’s public clearance lookup in September 2026, first by trade name, then by the owner’s personal name, then by any legal or numbered-company name found in public records. A match was accepted only when the account’s address fit the company’s location.
• Certification. Staff named on each company’s website were looked up in ISA’s public credential directory, in sweeps on October 8, 10 and 12, 2026. A person was credited only when exactly one same-name ISA profile held the credential the company claimed. The directory is opt-in, so someone not found may still be certified. There are many common first/last names that appear multiple times in the directory. Believe it or not, it can be hard to distinguish if one of them is the actual person that works for ABC Tree Company.
• Point in time. WSIB status and credentials change. This is a snapshot, and no individual company is named in this report.

Sources

Last edited on October 14, 2026