Quercus ilex
Common Name: holm oak 
Type: Broadleaf evergreen
Family: Fagaceae
Native Range: Mediterranean
Zone: 7 to 10
Height: 40.00 to 70.00 feet
Spread: 40.00 to 70.00 feet
Bloom Time: April to May
Bloom Description: Yellowish-green
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Hedge, Shade Tree, Street Tree
Flower: Insignificant
Leaf: Evergreen
Fruit: Showy
Other: Winter Interest
Tolerate: Drought

Culture

Winter hardy to USDA Zones 7-10 where it is best grown in rich, moist, well-drained loams in full sun to part shade. Grows well in sandy loams. Established trees have some resistance to brief periods of drought.

Noteworthy Characteristics

Quercus ilex, commonly called holly oak or holm oak, is a medium to large evergreen oak that typically grows to 40-70’ (less frequently to 90’) tall and features upright branching, dense foliage, a rounded crown with branches extending near the ground and fissured gray bark. It is native to the Mediterranean region (southern Europe and northern Africa), with a concentration in forested areas on the Iberian Peninsula. It was introduced to California in 1858, and has now naturalized along the coast from San Diego north to British Columbia.

Leathery, ovate, dark green evergreen leaves typically grow to 3” long by 1” wide and are downy gray beneath. Leaves may reach 5” long on suckers. Leaf margins have spiny-edged, holly-like teeth when young (hence the common name of holly oak), but become smooth-edged with age. Ornamentally insignificant, monoecious, yellowish-green flowers (females in small clusters and males in dangling catkins) bloom in April-May. Female flowers are followed by small acorns (each to 1 1/2” long) which ripen in September-October. Each acorn is enclosed within a scaly, rough-textured cup which covers about 1/3 to 1/2 of the acorn.

Genus name comes from the classical Latin name for oak trees.

Specific epithet is the genus name for holly in reference to the holly-like shape of some leaves.

Holm comes from the Middle English word holing meaning prickly.

Problems

No serious insect or disease problems. Oaks in general are susceptible to a large number of diseases, including oak wilt, chestnut blight, shoestring root rot, anthracnose, oak leaf blister, cankers, leaf spots and powdery mildew. Potential insect pests include scale, oak skeletonizer, leaf miner, galls, oak lace bugs, borers, caterpillars and nut weevils.

Garden Uses

Shade tree. Street tree. Woodland gardens. Clip for growth as a hedge.