The holm oak (Quercus ilex), also known as the holly oak or evergreen oak, is a large, evergreen tree with a rounded crown. The young leaves look similar to holly leaves and have white undersides, while the older leaves have smoother edges. In June new, whitish young leaves appear at the same time as yellow catkins. After being pollinated by wind, the female catkins develop into acorns, which are smaller and more pointed than those of our native English oak (Quercus robur) and sessile oak (Quercus petraea).
Holm oak is tolerant of salt spray and strong winds, so is a good choice for coastal gardens and is often planted as a windbreak. It's also tolerant of pollution, so can be grown in urban gardens. Holm oak can also be clipped into large topiary shapes or grown as a hedge. It's also one of the best screening trees.
Holm oak is native to the Mediterranean and was introduced to Britain in the late 1500s. In severe winters it may lose its leaves or die, so is best grown in milder parts of the UK.
The holm oak is not as good for wildlife as our native oak (Quercus rubra) but the catkins are a source of pollen for bees and other insects, and large birds and small mammals eat the acorns. Its dense, evergreen canopy gives year-round shelter for birds.
How to grow holm oak
Grow in any well-drained soil, in sun or partial shade. As it may suffer in severe winters, grow it in milder parts of the UK. Prune to shape in summer if needed.
Holm oak: jump links
- Planting holm oak
- Caring for holm oak
- Propagating holm oak
- Growing holm oak: problem-solving
- Buying holm oak
Where to grow holm oak
Grow in any well-drained soil, in full sun or partial shade. As it may suffer in severe winters, it's most suitable for milder parts of the UK.
How to plant a holm oak
- Stand the tree in water to ensure its roots are damp
- Dig a square hole that’s slightly wider than the pot your tree is in, but no deeper. Lightly fork the base and sides of the hole to ensure the soil isn’t compacted
- Remove the pot from container-grown trees and any wrapping from bare-root ones. Tease out and unwind any circling roots. Stand the tree in the planting hole, then lay a cane across the hole to check that the top of the rootball is level with the soil surface
- Backfill around the rootball with the excavated soil, shaking the tree a little to help the soil settle around the roots. Use your heel to firm gently all around the rootball and ensure there is good contact between the roots and the soil
- If planting in an exposed site, stake the tree to prevent windrock, which can tear the roots and create a gap around the base of the trunk that can fill with water and encourage rot. The stake should be about a third of the height of the tree, hammered in at a 45° angle. Attach the trunk to the stake using an adjustable tree tie
- Water the tree thoroughly, then keep it watered during dry spells for at least the first year
Read our detailed guide to planting trees.
Caring for holm oak
Keep your tree well watered in its first year, while its roots are establishing. Mature trees are drought tolerant and should get all the moisture they need from rainfall. Holm oaks do not need pruning but if you want to clip a tree or hedge into shape, do this in summer.
How to propagate holm oak
Holm oak can be propagated from its acorns (seeds). Sow when they are fresh, from September to December.
- Plant in individual small pots, filled with peat-free multipurpose compost, around 1cm deep
- Place in a cold frame or sheltered part of the garden. Protect from animals and birds
- Pot on into larger, deeper pots once roots begin to fill the opt. Grow on in a sheltered spot
Growing holm oak: problem solving
Some leaves are likely to fall in late spring and summer as the new ones emerge. This is normal and nothing to worry about. The tree may also lose its leaves in severe winters.
Aphids can be a problem on holm oaks. These are often dealt with by birds and other predators.
Leaf miners can affect the leaves – you may see blotches or 'mines' (wiggly lines) on the leaves. This does not affect the vigour of the tree and the affected leaves are usually replaced by fresh ones in late spring and early summer.
Holm oak is occasionally affected by two serious diseases of English oaks, oak decline and acute oak decline.
Advice on buying holm oak
- Holm oaks are sold as potted trees or as smaller plants for hedging. A tree may also have been grafted on to another rootstock
- If you are looking for instant impact, buy the biggest tree you can afford
- Buy from a specialist tree retailer or online supplier