How often should you trim trees away from the house?

Short answer

Trim the trees and shrubs away from the house once a year. Fast-growing species, like silver maples, willows and most hedges, need it twice a year. The best time for trees is late winter, while they're dormant and you can see the structure of the branches without leaves in the way. Doing it yourself takes 60 to 180 minutes and $0 to $50 in tools. An arborist charges $200 to $800 to trim a mature tree. Any branch over a power line is the utility's job, not yours.

Why it matters

A branch that touches the roof does damage every time the wind blows. It scrapes the granules off the shingles, lifts their edges, and gives squirrels and raccoons a bridge onto the roof and into the attic. Leaves from an overhanging tree fill the gutters in weeks. A shrub pressed against the siding holds moisture there and keeps the wall from drying, which is how rot and carpenter ants get started. One crowding the outdoor AC unit chokes the airflow the unit needs to shed heat.

Then there's the storm. A heavy limb over the house is a limb that can come through the roof, and a tree that hasn't been thinned catches wind like a sail. Trimming keeps branches off the roof, the gutters clearer, pests on the ground, and the risk from a storm smaller. It's also the single easiest way to add years to a roof that costs $8,000 to $25,000 to replace.

When to do it more often

Fast-growing species: twice a year. Silver maple, willow, poplar, and hedges like privet and arborvitae put on enough growth in a season to reach the house again by fall.
Branches over power lines: call the utility rather than cutting. Most utilities trim near their lines for free, and a branch that falls onto a line can electrocute whoever is holding the saw.
After a storm: look for cracked or hanging limbs, which should come down before the next wind does it for you.

What you need

Pruning shears, for anything up to about finger thickness
Loppers, for branches up to wrist thickness
A pole saw, for limbs you can reach from the ground, which is the only place you should be cutting from

Steps at a glance

Walk the house and mark every branch touching or hanging over the roof, siding, gutters or AC unit, and every shrub within arm's reach of a wall.
Cut small branches back to a side branch or the trunk, leaving the collar where the branch meets the trunk.
Use the pole saw on limbs you can reach from the ground, cutting from underneath first so the bark doesn't tear.
Cut shrubs back so there's open space between them and the wall, and clear everything within arm's reach of the AC unit.
Remove dead, cracked or crossing branches while you're at it.
Stand back and check that nothing still touches the house and no limb hangs over the roof.

You're done when nothing touches the house, the gutters have clear sky above them, and the AC unit has open space on every side.

Signs it's overdue

Branches touching the roof or siding, or scraping in the wind.
Leaves filling the gutters faster than you can clean them.
Squirrels on the roof, which got there from a tree.
Limbs over the power line.
Shrubs pressed against the AC unit or the wall.

DIY or pro

This is a moderate job from the ground, with shears, loppers and a pole saw. It's a dangerous one the moment you climb. Anything that needs a ladder against the tree, a chainsaw above shoulder height, or a cut on a limb heavier than you can hold is an arborist's job. So is anything near a power line.

An arborist charges $200 to $800 to trim a mature tree, and the price depends on the size of the tree and how close it is to the house and the lines. An arborist also knows how much to take off without stressing the tree, which matters for the big shade trees that keep the house cool. Get the arborist for the trees and do the shrubs and small branches yourself.

Safety

Ladder and heights: don't climb a ladder leaned against a tree to cut, and don't climb the tree. Cut what the pole saw reaches from the ground and leave the rest to an arborist with a bucket truck or climbing gear.
Electricity: a branch touching a power line can carry current down the branch and the saw into you. Don't cut any branch near a line, and call the utility to do it.

FAQ

When is the best time to trim trees?

Late winter, while the tree is dormant. You can see the branch structure, the tree heals fastest, and there are no leaves to haul away.

How far should trees be from a house?

Far enough that no branch reaches the roof or the gutters, and shrubs should leave open space between themselves and the wall so the siding can dry.

Can I trim a branch over a power line myself?

No. Call the utility. Most will trim near their lines at no charge, and a branch on a line can electrocute the person cutting it.

How much does it cost to trim a tree?

An arborist charges $200 to $800 for a mature tree, depending on its size and how close it sits to the house and the power lines.