How big does an oak get?
PlantNET describes English oak (Quercus robur) as a deciduous, broad-crowned tree to 20 m or more, with wide-spreading branches and grey, furrowed bark. It's native to Europe, North Africa and western Asia, is grown mostly in cooler regions here, and has naturalised in South Australia. It flowers in spring before the leaves appear, and drops acorns 2 to 4 cm long on long stalks.
The evergreen holm oak (Quercus ilex) is smaller in the street, where the City of Sydney gives it a potential height of 12 to 15 m. With any oak, plan for the spread: the branches reach out over roofs, fences and driveways.
Termites in the root crown
A South Australian Museum zoologist told the ABC that the termite Coptotermes acinaciformis is commonly found in eucalypts and oaks, typically in dead stumps, root crowns or the bowls of trees, and can move up to 50 metres underground looking for food. If an old oak's base sounds hollow or a nearby stump has termites, have an arborist assess the tree and a pest inspector check the house. Our pests and diseases guide has more.
On roots generally, we found no reliable source for oaks, so we won't guess how they behave near foundations or pipes.
What can I prune on an oak?
You can
- Take off small dead or crossing twigs you can reach from the ground, with secateurs or a pruning saw. Gardening Australia says dead stems and branches can be cut out at any time.
- Rake up leaves and acorns, and pull oak seedlings out of garden beds.
- Keep parked cars and stacked materials out from under the canopy.
Leave to an arborist
- Crown lifting or thinning on a mature oak (see crown thinning and lifting).
- Long, heavy limbs over the house or the street.
- A tree showing termites, decay or a hollow base.
- Any removal, and grinding a big stump.
Are oaks protected?
Oaks turn up on registers across the south-east. Bayside's significant tree register lists a row of pin oaks along Vincent Street, Sandringham. Glen Eira's classified trees include a holm oak and an Algerian oak in Caulfield Park, and Ballarat replaced damaged Avenue of Honour trees with pin, English and Turkey oaks.
In Victoria's residential zones, size alone can bring a permit into play. Since 24 September 2026, Clause 52.37 treats a tree at least 5 metres tall with an average canopy at least 4 metres across as a canopy tree, and a grown oak near a boundary is likely to qualify. See our Victorian permits page, or the tree removal permits page for other states.
Oak trees: what to do next
We'd have an arborist look at a big oak's base and its longest limbs before planning any pruning, and we'd ask the council about protection before booking anything heavier than clearing out deadwood.
Want an arborist to look at it?
Tell us the job and your postcode, and a local arborist calls you to talk it through.