Our California native Valley Oak is the tallest oak in North America. It is native to stream sides and deep soils in the Central Valley, and beautiful groves of large, old Valley Oaks line many of the rivers. The Valley Oak loves the fertile soils near streams where it has the ability to tap into deeper soil water.But it can also thrive in more urban areas, if it has room enough to grow and infrequent summer water.
Valley Oaks grow fast if they are in a situation they like. As the tree matures, it develops a large spreading canopy with branches that droop picturesquely down to the ground. Valley Oak leaves are green, range from small to large and are beautifully lobed. The lobes are rounded and the divisions between lobes go in almost to the midrib. (Blue oaks have lobed leaves that are shallowly lobed and the leaves are blue green)
When mature, Valley Oaks bear large acorns in the fall. These acorns were used by local Indians as a major food source. The acorns require processing before eating to leach out toxins. But this will not stop animals from eating them in the fall.
Valley Oaks are well suited for low irrigation landscapes. If watered frequently in the summer, these oaks are not able to defend themselves from fungal diseases that live in our soils. They may grow well when young, but eventually many will succumb to root disease.
Keep your Valley Oak healthy by watering it as infrequently as possible, monthly might be ideal, but many trees seem to thrive on twice that frequency of water. The water should penetrate deeply-18″-24″ and be applied around where the canopy edge is and outward as these tree have spreading roots. A soaker hose or in-line drip emitters are ideal. A thick layer of woody mulch, like bark or wood chips, will keep the roots cool and conserve moisture in the soil.
Height: 40-90 feet
Spread: 50-90 feet
Growth Rate: Moderate to fast
Irrigation needed: very low to low
Fall Color: None
Flowers: Catkins, not showy in spring
Seeds/Fruit: large acorns
Foundation: 20 feet
Drives/Patios: 8 feet
Fence: 6 feet
Too tall for growing under high-voltage overhead power lines