Hiring an Arborist

Hire An Arborist

Arborists are professionals trained and certified in the best current practices of planting, caring for and maintaining trees.

Consulting arborists are the preeminent authorities on matters related to trees. They bring a comprehensive, objective viewpoint to the diagnosis, appraisal and evaluation of arboricultural issues.

Canopy recommends hiring a consulting arborist to confirm that costly treatment, large tree pruning or removal is needed before hiring a tree service to do the work.

To find a certified consulting arborist in your area, use Canopy’s searchable Arborist List.

Hire an arborist to:

  • Train or prune young trees to develop strong structure
  • Do preventive health/safety check-ups to keep trees healthy and prevent hazards
  • Correct limb damage; remove dead and diseased wood
  • Remove excessive weight at branch ends and prune as needed
  • Diagnose for pests and diseases, determine treatment or fertilization needs
  • Choose the right tree for your site, or transplant existing trees to better locations
  • Remove a tree or grind out a stump

Hire a consulting arborist to:

  • Assess tree safety to protect people, and structures such as houses
  • Appraise the value of a tree
  • Diagnose and recommend treatment for a problem
  • Get a second opinion to help you decide on tree work or removal
  • Provide legal expertise and arborist reports for a court case or ordinance-protected tree
  • Provide advice about construction to avoid harming existing trees

Selecting an Arborist


Canopy recommends hiring an ISA (International Society of Arboriculture) certified arborist, or a consulting arborist who is a member of the ASCA (American Society of Consulting Arborists). Additionally, it is best to use an arborist who is familiar with the trees and ordinances of the City of Palo Alto, or the municipality where the work will be performed.

To locate a certified arborist in your area, or to verify a certification, search the ISA directory.

To locate a consulting arborist in your area, or to verify membership, search the ASCA directory.

To locate an arborist or tree care specialist in the Palo Alto area, see the Canopy Arborist List.

In California, a valid California contractors license is required if a project costs $500 or more. Verify the status of a contractor’s license and get information on complaints by contacting the Contractors State License Board at (800) 321-2752, or visit their website.


Ask to see insurance certificates as proof of liability for personal and property damage and workmen’s compensation. Phone their agent to verify current status and amount of coverage ($300K to $1M recommended). Under some circumstances YOU can be held financially responsible if an uninsured worker is hurt on your property, or if your neighbor’s property is damaged.

Get a Written Bid

Ask over the phone if you will be charged for an estimate before setting up an appointment. Remember that you will always be charged a separate consulting fee for advice outside of the work being bid on.

Ask two or more arborists to write a bid, including:

  • Timeframe for work and project completion.
  • Detailed description of work to be performed for each tree. Example: “Prune all dead, dying, diseased and weak branches 1-1/2 inches or greater in diameter.”
  • Statement that work will be supervised by an ISA certified arborist to A.N.S.I. A300 standards and/or that Western Chapter ISA Certified Tree Workers will be performing the work.
  • For insect or disease control, details of specific pests to be treated, what the manufacturer recommends for safe and effective use of a pesticide and their qualifications to make the recommendations and applications.
  • In Palo Alto, call the Santa Clara County Division of Agriculture at 408-918-4600 or visit their website for more information on pesticides.
  • The name of the fertilizer recommended to be used, the grade, rate and method of application.
  • Cleanup procedures should be described, including whether wood will be cut into fireplace lengths, or hauled away.
  • The total dollar amount to be charged. Work is usually bid as a fixed price for the entire job, or billed on an hourly basis plus materials. If the bid uses an hourly rate, ask to have the phrase “…but not to exceed $___…” included in the written bid.
  • Clarify if the tree removal bid includes obtaining a tree removal permit and the cost of grinding out the stump and surface roots (and to what depth), hauling the stump chips, filling with topsoil, and planting a new tree.

A Few Cautions

  • If a dispute arises or you would like an expert to check the quality of work performed, seek the services of a consulting arborist, your city arborist, or a similar specialist who is not in competition with the arborist you hired.
  • NEVER allow a tree to be “topped.” Topping is the practice of cutting large limbs off a tree or “stub cutting.” Topping removes too much of a tree’s foliar canopy at once, weakens the tree and causes tree hazards, premature decline and tree death. Qualified arborists will not “top” a tree; they will suggest moving, correctly pruning or replacing with an appropriate species.
  • Off-the-street sales pitches or companies without a listing in the phone book or certification are often made by honest, hard-working people who do not understand why they are unqualified to give advice about trees. Don’t be scared into removing a tree by an unqualified person giving you an opinion that the tree is “dangerous.”
  • Mature trees contribute up to 15% of your property’s value. Unsound work can cost money and create a dangerous hazard invisible to an untrained eye.

Be aware that a well-pruned tree, like a good haircut, may appear at first glance as if no work was done at all, even after an arborist has spent many hours removing numerous carefully-selected branches.

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