Bad pruning kills more Melbourne trees than any pest or disease. Incorrect cuts leave wounds the tree cannot seal, invite rot and insects, weaken the structure, and in the worst cases kill the tree within a few years. Here are the seven most common tree pruning mistakes — and how to avoid them.
1. Topping the Tree
Topping is the practice of cutting off the entire upper canopy of a tree, leaving just a stump of the main trunk or a few short branches. It is the most damaging thing you can do to a mature tree.
Why it is bad:
- The tree loses its food-producing leaves and starves
- Large cuts do not seal properly, inviting rot and disease
- New regrowth is weakly attached and will fail in a storm
- The tree’s structural integrity is permanently compromised
If a tree is too big for its space, the fix is reduction pruning by a qualified arborist, or full removal — not topping. Topping is sometimes sold as “lopping” by cheap operators. See our guide on tree lopping vs pruning for the full story.
2. Flush Cuts (Cutting Too Close to the Trunk)
A flush cut removes a branch right at the trunk, with no stub at all. It looks clean, but it removes the “branch collar” — the slightly raised ring at the base of the branch.
The branch collar contains special tissue that seals the wound. When you cut into or through the collar, the tree cannot seal properly, and decay moves into the trunk.
How to avoid it: Make your cut just outside the branch collar, leaving a small ridge around the cut. The collar should stay on the tree.
3. Leaving Long Stubs
The opposite mistake: leaving a long stub of branch sticking out from the trunk. The stub cannot seal because the branch collar is too far from the cut.
What happens: the stub dies back, the dead wood hosts rot and insects, and eventually the decay reaches the trunk through the dead stub.
How to avoid it: Cut just outside the branch collar — not halfway along the branch.
4. Pruning at the Wrong Time of Year
Every tree has a best time to be pruned. Cutting at the wrong time can stress the tree, cause excessive sap bleeding, invite specific pests, or remove next season’s flowers.
- Summer-pruning stone fruit invites silver leaf disease on cherries and plums
- Spring-pruning eucalypts can cause massive sap flow
- Winter-pruning spring flowerers removes the next season’s flower buds
- Autumn-pruning natives can trigger a weak flush of growth that dies in the first frost
The best time varies by species. For a detailed breakdown, see our guide on the best time to prune trees in Melbourne.
5. Over-Pruning (Removing Too Much at Once)
The 25% rule: in any one pruning session, never remove more than 25% of the tree’s live canopy. Many amateur pruners remove 50% or more, expecting it to grow back “thicker and bushier.”
What actually happens:
- The tree loses the leaves it needs to produce food
- It responds with panicked, fast “water sprouts” that are weak and ugly
- The tree uses stored energy to survive, weakening it for years
- Sun-scald can damage bark that was previously shaded by the canopy
A healthy tree can handle a light annual prune of 10-15% of the canopy forever. Heavier pruning should be the exception, not the norm, and only done over multiple seasons.
6. Using Blunt or Dirty Tools
Pruning tools matter more than most people realise. Blunt secateurs or saws crush the stem instead of slicing cleanly. Dirty tools transfer disease from one tree to the next.
Problems caused by bad tools:
- Crushed cuts do not seal properly
- Ragged edges let water and pathogens in
- Fungal and bacterial diseases spread between trees
- The job takes longer and you tire faster, leading to sloppy cuts
How to avoid: sharpen secateurs and saws regularly. Clean blades with methylated spirits or a 10% bleach solution between trees, especially if one tree is unhealthy.
7. Pruning Without a Plan
The biggest mistake: picking up the secateurs and cutting “whatever looks out of place.” Pruning should start with a clear reason and a plan.
Before you cut anything, ask:
- Why am I pruning this tree? Clearance, shape, health, view, fruit, structure, or safety?
- What is the target final shape? Walk around the tree first and visualise it.
- Which branches serve that goal? Identify specific branches to remove or shorten.
- What is the maximum I should remove? Stick to 25% of live canopy.
Without a plan, it is easy to keep cutting “just one more branch” until the tree is over-pruned. Stop, step back, and review every few cuts.
The Three-Cut Method for Larger Branches
For any branch over about 3cm thick, use three cuts instead of one:
- First cut: About 30cm out from the trunk, on the underside of the branch. Cut about a third of the way through. This stops the bark tearing when the branch falls.
- Second cut: About 5cm further out from the first cut, from the top. Cut right through. The branch falls cleanly.
- Third cut: Remove the remaining stub, just outside the branch collar.
This method prevents the most common damage — bark tearing down the trunk when a heavy branch falls unexpectedly.
When to Call a Professional
Call a qualified arborist instead of DIY if:
- The tree is taller than 4 metres
- You would need a ladder to reach the branches
- Branches are near power lines
- You suspect structural issues or disease
- More than 20% of the canopy needs attention
- The tree is valuable, old, or has heritage significance
A certified arborist (AQF Level 3 or higher) understands tree biology, structural assessment, and proper cutting technique. A few hundred dollars for a professional job can save thousands in future problems or tree replacement.
Get Expert Pruning Done Right
Precision Arbor Care provides qualified tree pruning across Melbourne, from shaping ornamentals to reduction pruning on large natives. Call Rob on 0413 606 544 for a quote, or visit our tree pruning services page to learn more.
