PlantFiles: Cork Oak
Quercus suber

I planted a 6' quercus suber in Encinitas in 1986. It is now aprox 30' tall with an equal spread. It is a beautiful and hardy tree. After the first year I have never watered nor fertilized this tree. Though it is evergreen it sheds leaves in the spring as the new growth appears. If there are plants below the canopy this adds work to a gardener's busy spring schedule.
The only drawback is that the deeply fissured bark makes it difficult to keep ants away. The ants allow the new growth to be infested with aphids......black sooty mold forms on the leaves. This does not seem to harm the tree but I am sure it slows the growth.
Mystic

One interesting use for the cork-like bark was during WWII, when the cork was used to cushion fragile items during transport, similar to the ubiquitous Styrofoam "peanuts" we use now. Many sources report Quercus suber is hardy to zone 7.

Monoecious tree, perennial of the Fagaceae family and of the Quercus gender, 10 – 15 (-20) m high and 4 – 5 m high in DAP (diameter 1.30m from the ground), with a wide and not very dense crown
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Trunk with thick branches and covered by a thick, cracked rhytidome, the cork. Leaves: coriaceous (falling in the Spring of the second year) slightly serrate and denticulate, dark green and glabrescent on the upper side and whitish and stellate-tomentose on the underside. Masculine and feminine flowers arranged in a spicate inflorescence; flowering almost all year, the main flowering period being between April and July.
Fruit: a glans commonly called acorn, has various periods of fructification; the first, bastão, ripens in September – October; the second, lande, is generally more abundant, ripening in November – December and the last, landisco consists of small fruits of an imperfect maturation.

It is a slow-growing species living for up to 300 years or longer.


Ecology

Characteristic of areas with a Mediterranean climate, though requiring a lot of atmospheric humidity. The areas where the species prospers best require an average rainfall of between 600 and 800 mm a year. However, it tolerates average annual rainfall close to 2 000 mm.

If the rainfall drops to 400 mm the cork oak starts to regress.

The cork oak cannot withstand winter temperatures lower than -5ºC.

As far as altitude is concerned, cork oaks grow best in regions lower than 200 m.

Cork oaks grow in almost any kind of soil, except in soils with a compact calcareous content.