Signs a tree in your garden could be dangerous

Published 2 November 2026

Most garden trees are perfectly safe, and a big tree isn’t a dangerous tree just because it’s big or sways in the wind. But trees do change. Decay, disease, storm damage and root disturbance can turn a healthy tree into a problem over a few seasons, and the owner is the one who needs to notice. This guide covers what to look for, who is responsible in Swansea, Neath Port Talbot and Carmarthenshire, and what the Welsh rules say if the tree is protected.

Start with the question of who is responsible

If a tree grows on your land, it’s yours to look after. Neath Port Talbot Council’s tree plan puts it plainly: “All trees on privately owned land are the responsibility of the landowner/tenant”, and landowners “have a legal requirement to ensure that trees on their property are maintained to a safe standard.” Carmarthenshire Council says the same in its own tree strategy, and its ash dieback advice is headed “If you own a tree, it is your responsibility.”

Swansea Council’s tree policy explains why this matters: if a tree falls or causes injury or damage, its owner could be held liable if they “omitted to take sufficient care of the tree.” None of the three councils inspects private trees for you. Both NPT and Carmarthenshire advise owners to have trees checked by a suitably qualified arborist if they’re unsure.

A walk-round check you can do from the ground

You don’t need to climb anything. Walk round the tree once a year, and again after strong winds, and look from the ground for:

• Broken, snapped or hanging branches. A hanging branch caught in the crown is the classic sign that needs dealing with soon.
• Dead branches, or a tree that is dead. Bare limbs in summer, or bark falling away, stand out against a healthy crown.
• Cavities or holes in the trunk or main branches.
• Fungal fruiting bodies (mushrooms or brackets) on the trunk, at the base or over the roots.
• Cracks, splits, swellings or bulges in the trunk or branches.
• A new lean, or movement in the root plate. A tree that has always leaned is less of a worry than one that has started to, or where the soil on one side has lifted or cracked.
• Leaves that wilt, discolour or drop in summer, or dark staining and patches on the bark.
• Bark damage, including damage from strimmers, mowers or vehicles.

This list follows a standard council tree-owner checklist. One sign on its own doesn’t mean a tree must come down. It means it’s worth having someone who knows trees take a closer look.

“Dangerous” versus “about to fail”

There’s a difference between a tree with a defect and a tree that is about to come down. Swansea Council’s policy describes imminent danger as a tree, or a substantial part of a tree, that is “about to fail at any moment.” That’s the kind of situation where work can’t wait: a large limb hanging over a path, or a tree that has started rocking at the base after a storm. Keep people away from it and get it looked at.

Most defects are slower. A bracket fungus, a crack in a fork or a thinning crown usually gives time to get advice and plan the right work, which may be deadwooding or a crown reduction rather than taking the whole tree down.

Ash dieback: the one to keep an eye on

Ash is common in gardens, hedges and field edges across the area, and ash dieback has made many of those trees weaker. Carmarthenshire Council has reminded owners that trees next to roads are “the responsibility of the landowner” and should be “maintained to a safe standard,” and recommends using an accredited tree surgeon to fell a tree. If you have ash, look for dying-back shoots and thinning crowns in summer. Our ash dieback page explains what we look for and the options.

If the tree is protected

Many trees around Swansea are covered by a Tree Preservation Order. Swansea Council says it has “over 560 separate TPOs,” and trees in conservation areas such as Mumbles and several Gower villages are protected too. You can check Swansea’s TPO map, though the council says it isn’t a legal record, so ask the council before any work.

Under the current rules in Wales, you don’t need consent to cut down or cut back a protected tree that is “dying, dead, or dangerous.” But the Welsh Government’s Protected Trees guide advises giving the council at least five days’ notice first, except in an emergency. That’s in your interest: you could be prosecuted if the council thinks the work was unauthorised. Unless the council says otherwise, you’ll usually have to plant a replacement tree. Take dated photos of the problem before anything is cut.

These rules are about to change. The Planning (Wales) Act 2026 brings in new tree preservation rules. The Welsh Government expects them to come into force around October 2027, and it has proposed tightening the “dangerous” exception. Until then the existing rules apply. Our guide to whether you need permission to cut down a tree in Swansea covers consent and conservation-area notices in more detail.

If the tree is next door, or on council land

If a neighbour’s tree worries you, talk to them first. NPT and Carmarthenshire both advise contacting the owner, then taking legal advice if that gets nowhere. Swansea’s policy says trees that are “merely causing a nuisance” remain “a private matter between the two parties.” Our guide to a neighbour’s tree overhanging your garden covers what you can cut back yourself.

For a council-owned tree, contact the council: Neath Port Talbot lists 01639 686868. Swansea’s policy says the council aims to inspect all its own trees within a four-year cycle. Where a private tree threatens a road, Swansea can instruct the owner to make it safe under the Highways Act 1980.

How we help

If you’ve spotted any of the signs above, our teams can look at the tree, explain what’s wrong in plain terms and suggest the least drastic fix. That may be removing a dead limb, a reduction, or tree removal if the tree can’t be made safe. If it’s protected, we’ll tell you what notice the council needs before we start. If you’re on the coast, our guide to coastal gardens in Mumbles and Gower covers wind and salt damage too. Get a free quote.