Check for ISA arborist certification. ISA Certified Arborists are experienced professionals who have passed an extensive examination covering all aspects of tree care.
Ask for proof of insurance and then phone the insurance company if you are not satisfied. A reputable arborist carries personal and property damage insurance as well as workers’ compensation insurance.
Check for necessary permits and licenses. Some governmental agencies require contractors to apply for permits and/or to apply for a license before they are able to work.
Ask for references to find out where the company has done work similar to what you are requesting. Don’t hesitate to check references or visit other work sites where the company or individual has done tree work.
Get more than one estimate, unless you know and are comfortable with the arborist. You may have to pay for the estimates, and it will take more time, but it will be worth the investment.
Don’t always accept the low bid. You should examine the credentials and the written specifications of the firms that submitted bids and determine the best combination of price, work to be done, skill, and professionalism to protect your substantial investment.
Be wary of individuals who go door-to-door and offer bargains for performing tree work. Most reputable companies are too busy to solicit work in this manner.
Keep in mind that good arborists will perform only industry accepted practices. For example, practices such as topping a tree, removing an excessive amount of live wood, using climbing spikes on trees that are not being removed, and removing or disfiguring living trees without just cause are improper practices and violate industry standards.
Get it in writing. Most reputable arborists have their clients sign a contract. Be sure to read the contract carefully. Don’t be afraid to ask questions, such as:
When will the work be started and completed?
Who will be responsible for clean-up?
Is this the total price?
What are the terms of payment?
If I would like more to be done, what is your hourly rate?