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As a general rule, avoid planting under the canopy of oak trees. It is recommended that you remove non-native plants from under oaks but avoid disturbing the soil or drainage patterns in the process. If you need to plant something, choose species that require similar soil types and watering. Avoid azaleas and rhododendrons as they typically require more water than is appropriate for oaks and may transmit diseases such as Sudden Oak Death.
There are a number of common oak species in California including both tree species and shrub species.
Trees species:
Black Oak (Quercus kelloggii) Found in hilly regions between 2,000 and 6,000 feet. Typically associated with conifers and pines, firs, or incense cedars.
Blue Oak (Quercus douglasii) Found in the hot, dry interior foothills. Generally found below 3,500′.
Canyon Live Oak (Quercus chrysolepis) Evergreen oak found in foothills, steep canyons, and on slopes to 9,000′.
Coast Live Oak (Quercus agrifolia) Evergreen oaks found in coastal fog zones and in grassland savannas.
Engleman or Mesa Oak (Quercus engelmannii) Rare species found in scattered groups along the western edge of California deserts.
Interior Live Oak (Quercus wislizenii) Evergreen species usually found on uploand slopes below 5,000 feet , in low foothills and in hot dry canyons.
Island Oak (Quercus tomentella) Found on the Channel Islands off the coast. Typically in foggy areas often on north or north west facing slopes.
Oregon Oak (Quercus garryana) Found away from coastal fog on slopes and open valleys, usually between 1,000 and 5,000 feet
Shreve’s Oak (Quercus parvula var. shrevei) Similar in appearance, often found growing adjacent to, and may produce hybrids with Coast Live Oak.
Valley Oak (Quercus lobata) A deciduous tree species that can grow very large. Found typically inland from the coastal fog region, usually below 2,000 feet.
Illustrations by Michael Lee – Purchase his beautiful poster of the Native Oaks of California
The GSOB is a destructive insect pest that is decimating some oak species mostly in Southern California. It has been found infesting coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii) and canyon live oaks (Q. chrysolepis). It attacks the limbs of mature oak trees feeding in the conductive tissues and sapwood. Unfortunately the GSOB can be spread in cut firewood. Click here for additional information.
There are a number of common oak species in California including both tree and shrub species. See our CA Native Oaks post for detailed information.
Illustration by Michael Lee – Link to his beautiful poster of the Native Oaks of California
In general, healthy live oak trees are able to survive the dry seasons and extended droughts we experience in California. In most circumstances it is not necessary to water mature established live oak trees. Shallow watering can in fact cause additional problems. Over watering or improper watering of oak trees may promote the growth of bacteria that can damage the root hairs and the ability of the tree to absorb water from the soil. Deep watering of oaks may be appropriate in some circumstances, but it is advisable to consult a certified arborist regarding watering of oak trees especially mature trees.
