Currently, the Island oak is a relatively unknown California native tree throughout the Inland Empire. It is native to the coastal islands where it is adapted to winter rain, summer drought, fog, wind and humidity. Over time, a number of these trees have been planted throughout Southern California, including the Rancho Santa Ana Botanic Garden, that have increased its visibility and landscape interest.
Island oak becomes a large and stately tree over time with a dense foliage habit and rounded canopy. Mature sizes can range 40-50 ft. tall and as wide. Horticultural experience suggests that this oak is adapted to more summer water than the Coast live oak; young trees benefit from well-drained soils and moderate amounts of moisture through winter and spring, and monthly deep watering during summer. Mature trees show good adaptability to normal rainfall conditions, and tolerate heat, aridity and low amounts of summer moisture.