GardenersHQ

How to Grow Quercus ilex Plants in your Garden

Gardener's HQ Guide to Growing Holly Oak, Holm Oak

The Quercus ilex is an evergreen tree that is commonly known as the Holm, Evergreen, or Holly Oak. This tree is easy to grow and responds well to pruning; so can also make a good tall hedging plant; it is often used to form wind-breaks.

If not clipped or pruned and left to grow as a tree then expect it to reach a height of about 40 to 70 feet (12 to 21 m) with a similar spread.

Trees allowed to grow freely will develop a well rounded head; branches are low hanging. Bark is cracked and dark.

It gained its common name, the Holly Oak, because of the similarity of its leaves to that of the Holly tree (Ilex aquifolium).

Holly Oak

Holm Oak photograph by Wendy Cutler; CC.

The fruit (acorns) are edible and often used to make a flour, or may be toasted. It is an important food source for free range pig breeders.

Holly Oak is a slow growing long lived tree and some trees that are hundreds of years old have spreads of over 140 feet (43 m). Definitely one to plant for future generations.

Quick Growing and Care Guide

  • Scientific Name: Quercus ilex
  • Common Name (s): Evergreen oak, Holly oak, Holm oak
  • Growing Zone (USA / UK Hardiness): USA: 7 to 11 / UK: H4
  • Mediterranean area

Plant Details

  • Life Cycle / Plant Type: Evergreen Tree
  • Plant Height: 40 to 70 feet (12 to 21 m): in ideal circumstances (and a lot of time) oak trees can easily reach hights of 90 feet (28 m) or more.
  • Plant Spread: 40 to 70 feet (12 to 21 m).
  • Blooms: Mid to late spring.
  • Flower Details: Yellowish-green.
  • Leaf Foliages: Dark glossy green above; grey or tawny beneath. Narrowly oval, Ovate-lanceolate. Holly-like glossy leaf. Juvenile plants have a whitish down.
  • Fruit: Acorns. 1.2 to 2.5 cm (0.6 to 1 inch). On stalks, 1 to 3 acorns per stalk.

Growing Conditions

  • Best Light Conditions: Full sunlight or partial shade.
  • Suitable Soil Types: Well drained. Most soils but thrives in rich sandy loams.
  • Suitable Soil pH: Acidic through to slightly alkaline.
  • Soil Soil Moisture: Moist. Fairly drought tolerant once established.
  • Sowing, planting, and Propagation: Propagate by grafting towards the end of winter or in the middle of autumn. Sow ripe acorns on their sides in a seed bed when ripe. Sow about 0.5 to 1.5 inch deep (1.2 to 4 cm); bury at about 1.5x the acorns diameter. Transplant to final location after one to two years. Acorns take about 2 to 4 weeks to germinate.
  • Care: It is classified as RHS pruning group 1. This means that it requires minimal pruning; heavy pruning can be detrimental to growth. It is usually best to lightly prune towards the end of winter or at he start of spring. Aim to remove any diseased or damaged twigs.

Further Information

  • Best used for: Spectacle. Exposed areas. Shade. Hedge. Winter colour. Wildlife garden (attacts squirrels and birds).
  • Family:
  • Closely Related Species:
  • Miscellaneous: Long lived tree, many species are known to be at least 700 years old; and a specimen in Sicilly is thought to Malta may be up to 1,000 years old.
  • Family: Fagaceae.
  • Subspecies: Quercus ilex subsp. ilex (bitter tasting acorns); Quercus ilex subsp. rotundifolia (sweet tasting acorns).
  • Synonyms Quercus rotundifolia; Quercus ballota.
  • Closely related species and genera: Common Oak
  • .
  • Further Reading and References used for this Quercus ilex growing guide: Wikipedia; Arborday