What Is an ISA-Certified Arborist (And Why Should You Hire One)?

If you’ve been shopping around for tree service, you’ve probably seen the letters “ISA-Certified Arborist” in company bios or on service vans. But what does that actually mean — and should it change who you hire?

Short answer: yes, it should matter to you. Here’s why.

What Is the ISA?

ISA stands for the International Society of Arboriculture. It’s the main professional organization for tree care in the world, with members and certified arborists in over 40 countries.

To become ISA certified, an arborist has to pass a written exam that covers tree biology, soil science, pruning, risk assessment, pest management, and more. They also need at least three years of hands-on tree work experience before they’re even allowed to sit for the exam.

After they pass, they have to keep earning continuing education credits every three years to stay certified. So it’s not a one-and-done thing — they have to keep learning as the industry changes.

What Does a Certified Arborist Actually Know?

A lot more than most people realize.

Tree care looks simple from the outside — you cut some branches, clean up the mess, and leave. But done wrong, it can seriously hurt a tree. Over-pruning, cutting in the wrong spots, leaving stubs, topping a tree — all of these are common mistakes that weaken trees and shorten their life.

A certified arborist understands how trees respond to cuts. They know where to make a cut so the tree seals it properly. They know which branches to remove and which ones to leave. They can spot early signs of disease or structural problems that most people would completely miss.

That knowledge makes a real difference — especially for large or mature trees where a mistake is expensive and sometimes impossible to fix.

Red Flags to Watch Out For

Not every company that offers “tree service” actually knows what they’re doing. Here are some warning signs:

• They recommend topping the tree. Topping — cutting the main trunk or large upper branches down to stubs — is widely condemned by arborists. It weakens trees, creates rot entry points, and leads to fast, unstable regrowth. A knowledgeable company won’t suggest it.
• No proof of insurance. Legitimate tree companies carry both liability insurance and workers’ compensation. If they can’t show you a certificate, walk away.
• No credentials, no reviews, no references. Anyone can buy a chainsaw and call themselves a tree service. Look for companies with real history, real reviews, and people you can verify.
• They show up at your door after a storm. Storm chasers are common in tree service. They go door to door right after a weather event with low quotes and fast talk. Some do decent work, but many don’t — and they’re gone before you realize something went wrong.

How to Verify an Arborist’s Certification

You can verify any ISA-certified arborist on the ISA’s own website. Just go to treesaregood.org and search by name or location. Each certified arborist has a unique credential number that’s tied to their record.

This takes about 30 seconds and tells you whether their certification is current.

Does Every Job Need a Certified Arborist?

Honestly, not always. If you need a small decorative shrub trimmed or a young tree shaped, a general landscaper might be fine.

But for anything involving a large tree, a tree near your house or other structures, a tree that might be diseased, or a tree that needs removal — a certified arborist is worth it. The cost of getting it wrong is too high.

Think of it like this: you can change your own oil, but you bring your car to a mechanic when something’s actually wrong. Same idea.

What We Do Differently

Every job we do in Madison has an ISA-certified arborist on site. Not a crew member who watched some YouTube videos — an actual certified professional who knows tree biology and has years of real-world experience.

We’re also fully insured and give written quotes before any work starts. No surprises on the bill, no vague verbal estimates.

Get a free estimate from our team — we’re happy to walk through what your trees need and explain exactly what we’d do.