Tree trimming and pruning

Trimming or pruning: is there a difference?

Not really. Tree trimming is the more common search here, pruning is the word arborists tend to write on the quote, and both mean cutting selected branches to shape, clear or tidy a tree.

What matters is which branches come off and where each cut is made. A cut just outside the collar, the slight swelling where a branch joins the trunk, lets the tree seal the wound. Flush cuts and ragged stubs give decay a way in.

What kinds of pruning are there?

Canopy lifting. Taking off the lowest branches so you can walk, mow or park underneath, or let light into the garden. Done in stages, it leaves the tree balanced.

Thinning. Removing selected branches through the crown so more light and wind pass through. It brightens a shaded lawn and lightens a dense tree in an exposed spot.

Deadwood removal. Cutting out dead branches still on the tree before they fall. Auckland Emergency Management suggests removing diseased or damaged branches to help trees stand up to wind.

Clearing the roof and gutters. Shortening branches back to a side branch so they stop scraping the roof, filling the gutters or hanging over the drive.

Opening a view. Thinning or lifting part of a crown so you can see past it. Ask what the tree will look like afterwards, because a view cut too hard grows back thicker.

Reducing the crown. Shortening the crown (the leafy top) by cutting branches back to smaller side branches, which keeps the tree's natural shape at a smaller size.

Is tree topping the same as trimming?

No, though plenty of people ask for it, and lopping means much the same thing. Topping cuts the top or the main branches back to stubs, whatever their size, to make a tree shorter in one go.

It looks tidy for a season. Then each stub pushes out a cluster of fast, weakly attached shoots, and the big cut ends are slow to close and prone to rot. Within a few years the tree is often as tall as before, denser, and more likely to drop branches.

If height is the worry, ask for a crown reduction back to side branches, or ask whether the tree is simply too big for its spot. Our lopping vs pruning guide goes further.

Can you prune a protected tree?

Often, within limits your district plan sets. In Auckland, trimming a notable tree stays within the rules only if no branch over 50 mm is cut, no more than 10 per cent of live growth comes off in a calendar year, and the work meets best arboricultural practice. Anything beyond that needs resource consent.

Deadwood is treated differently there: removing dead wood from an Auckland notable tree is permitted when a qualified arborist does it, and needs consent when anyone else does.

Christchurch's District Plan sets out the pruning it allows on significant trees, and some of it may only be done by, or on the advice of, a works arborist competent to the NZQA Level 4 arboriculture standard. Other councils set their own limits, so check yours on our tree removal permits page first.

When should a tree be pruned?

It depends on the species, and there's no single New Zealand calendar for it, so ask the arborist. Dead, broken or rubbing branches are worth dealing with when you notice them, and the Insurance Council suggests checking trees before and after severe weather.

If you love a pōhutukawa's flowers, which come mainly in November and December, talk about timing before booking. Myrtle rust can travel on contaminated clothing and equipment, so clean tools matter around pōhutukawa and other natives in the myrtle family. Fruit trees have their own season: see fruit tree pruning.