Start at the base
- Heaved, cracked, or mounded soil on one side of the trunk. This can mean the root plate is moving, and it is one of the more serious things you can see.
- Mushrooms or shelf-like conks on the trunk base or over root flares — often a sign of decay inside.
- Missing bark or exposed, hollow-sounding wood at the base.
- Severed roots from recent trenching, a driveway, or a new patio.
- Root flare buried by fill or heavy mulch, which encourages rot.
Then look up the trunk
- Vertical cracks or seams, especially where two stems meet.
- Tight V-shaped forks with included bark — a classic failure point in storms.
- Cavities, old wounds, or large flush cuts from past bad pruning.
- Woodpecker activity concentrated in one area, which often follows soft wood.
- A distinct bend or bulge that was not there before.
Then the crown
- Dead top, or dead limbs high in the tree.
- Thin, sparse foliage compared with similar nearby trees.
- Leaves or needles emerging late, or dropping early.
- Hanging broken limbs caught in the canopy.
- One-sided, heavily extended limbs over a structure.
Do not wait on these
A new or worsening lean, cracked soil at the base, a split trunk, or a hanging limb over an entry, walkway, or driveway should be looked at promptly rather than after the next storm. If it is already in contact with a structure or a wire, treat it as emergency tree service and involve 911 or your utility where lines are involved.
Context matters as much as condition
Risk is condition plus target. A hollow alder at the back of five acres is a wildlife tree. The same alder over a child's bedroom is a different conversation. When you describe a tree in a quote request, describe what is underneath it too.
What you cannot see
Internal decay, root disease, and compromised anchorage frequently do not show clearly from the ground. If a large tree sits within striking distance of your house, a professional assessment is a reasonable expense — and much cheaper than the alternative.