Why I Went Back to School: Prescription Pruning and What It Means for Your Trees

Most days, I'm the one doing the teaching. I train climbers all around the world, I walk new crew members through their cuts, and I've spent years designing climbing gear other arborists use every day. But one of the values I've built Koala Tree on is that learning never stops, no matter how long you've been in the trees. So this fall I crossed the border to Ohio and became the student again.

The course was the Prescription Pruning Qualification, or PPQ, run by the Ohio Chapter of the International Society of Arboriculture. It's open only to ISA Certified Arborists, it takes three days of classroom and field work plus an exam, and it builds on decades of pruning research by Dr. Ed Gilman. It's still new on this side of the border, and as far as I know, I'm one of very few arborists in Ontario, if not the only one, who holds it. Here's why it matters to you as a homeowner.

The problem PPQ solves

When most people hire a tree company to "trim the tree," the decisions about which branches come off get made up in the canopy, in the moment, by whoever happens to be climbing. Even with good climbers, that leads to uneven results. One crew takes a little. Another takes far too much. The tree pays for it either way.

The industry pruning standard (ANSI A300) tells arborists what a job should achieve, like reducing risk, adding clearance or improving structure. What it doesn't do is spell out exactly how to get there on your particular tree. PPQ fills that gap.

What a pruning prescription looks like

The idea behind PPQ is simple: no tree gets pruned without a written prescription, the same way a doctor wouldn't hand you medicine without writing down the dose. A prescription covers:

• What you and the tree are concerned about, like more light on the lawn or a heavy limb over the driveway
• The objective, such as taking weight off the three largest limbs
• How many cuts, how big they are, and what type of cut
• Exactly where on the tree those cuts go
• Limits, meaning what the crew must leave alone

So instead of "thin it out a bit," the plan might read: make 20 to 25 reduction cuts about 2 inches across at the ends of the three largest limbs, remove dead wood over 1 inch, and take nothing from the main leader.

Why this is better for your tree

Every cut is a wound the tree has to deal with. PPQ is built around removing the least living wood needed to reach the goal. Fewer, smarter cuts mean a tree that stays healthier, regrows more predictably and is less likely to fail later. It's the opposite of topping.

It also makes the work accountable. Because the plan is written down, you know what you're paying for before we start, and you can check the finished tree against it.

How it fits with the rest of our work

PPQ goes hand in hand with my TRAQ risk assessments and the decline management work we do on older trees. Assessment tells us what's going on with a tree. A prescription turns that into a precise plan the whole crew carries out the same way, every time.

The trainer becomes the trainee, and the crew wins

Every course I take comes straight back to the people I train. PPQ gave me a clear, shared language for teaching pruning, so what I learned in Ohio is now part of how my whole crew works. When someone from Koala Tree is up in your tree, they're following the exact plan I wrote on the ground, built on the latest research in the field.

If you have a tree that needs pruning and you'd like a plan you can read before any cutting starts, book an assessment and I'll write you a prescription.

This is general information. Every tree and site is different. For advice on a specific tree, get a free quote or book a Certified Arborist Assessment.

About the author

Jason Korkidakis

Jason is Koala Tree’s Owner and Lead Arborist in London, ON. He leads an 8-person crew and assesses trees for homeowners, condo boards and property managers.

ISA Certified Arborist ON-3263ATRAQ qualifiedPPQ qualified

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