Cooperative Extension Fresno County
University of California
Cooperative Extension Fresno County

Oak Trees

Oaks are frequently included in California landscapes, though many gardeners are unaware that they may require special treatment in order to thrive.  Some oaks, particularly native California species, are not well adapted to the home garden environment and may succumb to soil-borne diseases that can be avoided with proper management techniques.  Special care is needed when building around oak trees if the trees are to survive.  Strangely-shaped and often colorful galls are often observed on the leaves, twigs and branches of many oak species-fascinating but harmless. 

PLANTING UNDER NATIVE OAKS

In general nothing should be planted within a 10 foot radius of the trunk of a native oak. Do not irrigate, plant or disturb the soil in this area. Organic mulches at least 2 inches thick are very beneficial in this zone, and can look quite attractive. Generally, native oaks do not require irrigation. In case of severe drought, or root loss due to construction or transplanting, use drip irrigation only at and beyond the outer edge of the tree canopy. Never use a sprinkler system and do not wet the trunk to reduce the risk of root rot. Native oaks do not require fertilizer. Do not compact the soil, change the drainage patterns, raise or lower the soil grade, trench or cut roots or use a rototiller near native oaks. If paving is required, use porous paving, such as brick on sand or gravel, and sweep it during the summer months. Do not hose off. If landscaping is necessary, use drought tolerant native plants. Plant only outside or beyond the 10-foot area around the trunk. Bulbs and wildflowers, which do not require summer watering, can be used.

Suggested Plants Compatible With Oaks

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