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Holly OakQuercus ilex

  • Northern Red Oak - Quercus rubra
  • Holly Oak Tree

The holly oak is a long-lived, durable tree that will thrive in almost any location once established and stands up well to strong winds. When given adequate soil space, the tree does well along streets and parking lots and in parks and gardens in the western United States.

Its large size and dense crown ensure that this oak provides shade for large areas of the landscape.

Hardiness Zones

The holly oak can be expected to grow in Hardiness Zones 7–11. View Map

Tree Type

This is an evergreen tree, keeping its foliage year-round.

Mature Size

The holly oak grows to a height of 40–70' and a spread of 50–60' at maturity.

Growth Speed Slow to Medium Growth Rate

This tree grows at a slow to medium rate, with height increases of anywhere from less than 12" to 24" per year.

Sun Preference

Full sun is the ideal condition for this tree, meaning it should get at least 6 hours of direct, unfiltered sunlight each day.

Soil Preference

The holly oak tolerates a wide range of soil textures from acidic to slightly alkaline. It can also tolerate drought (once established) and salt.

Attributes

This tree:
  • Features simple, leathery, glossy dark green leaves that are 1–3" long with spine-tipped teeth along the margin, although some are untoothed. They have a stiff, holly-like texture.
  • Yields 1" round acorns that are greenish-yellow and brown and mature in the first year, dropping in the autumn.
  • Tolerates drought and salt.
  • Produces drooping catkins in the spring as it leafs out.
  • Grows in a rounded shape.
  • Is sensitive to cold.
  • Should not be overwatered once established, as this invites powdery mildew.
  • May require pruning when young to develop a strong branch structure.

Wildlife Value

Birds and squirrels are attracted to the holly oak for food and shelter.

History/Lore

The holly oak is native to the Mediterranean region. The range is from Spain along the Mediterranean fringe east toward western Pakistan. Other common names are Holm oak and evergreen oak. In the foothills of the Spanish Pyrenees, black truffles are grown on the roots of these trees.