El Dorado County | Sacramento County Arborist

California is blessed with about 22 species of native oaks. Some are trees and some are shrubs. Six of these species are commonly found in El Dorado County: the blue oak, valley oak, interior live oak, canyon oak, California black oak and huckleberry oak.

All of these except the huckleberry oak are adapted to summer heat and drought. The huckleberry oak is found at higher elevations in the Tahoe area and is a low-growing, evergreen shrub. Blue, valley and California black oaks are deciduous and the others are evergreen. The valley oak is the largest oak in the U.S. and found only in California. It used to cover much of the Central Valley and may live 500 years. A preserved section of a large valley oak trunk is in the lobby of El Dorado County Government Center, Building C, and the growth rings are marked with labels telling the dates the rings were formed.

The native oaks are survivors; most of them can take poor, rocky soil and little or no summer water. Unfortunately, they are not so good at surviving the changes that humans have brought to California. Clearing for building and agriculture have greatly decreased many native oaks species.

The type of landscaping that people have brought to California is not friendly to local oaks. Lawns and other thirsty landscapes are a death sentence to trees that are adapted to dry summers. Many native oaks will develop a fungal infection of their roots from summer irrigation and this kills them slowly, as evidenced by gradual loss of the leaf canopy.

Your tree service professional can share tips on healthy trees. Though Sacramento is home to a number of native trees, the most recognizable are our native oaks. The three most common native oak trees are the valley oak (Quercus lobata) the interior live oak (Quercus wislizenii) and the blue oak (Quercus douglasii). Oak trees can pollinate other oaks in the same botanical section and a number of hybrid oaks can be found at certain locations in Sacramento.

In eastern Sacramento County, blue oaks are most common. Blue oaks are well adapted for our Mediterranean weather patterns and thrive with wet winters and hot, dry summers. If this natural pattern is interrupted or altered (for example by the addition of irrigation within the area surrounding the tree) the blue oak will decline and not live out its potentially centuries long life span.

The valley oak is the largest tree in the valley. These trees love to grow in the deep soils left by the meandering rivers and flooding cycles of pre-settlement Sacramento. Though highly adaptable, they will grow in almost any of our valley soils if treated with care. These large trees prefer to keep their roots dry in the summertime and do not appreciate heavy irrigation.

The interior live oak is the most common evergreen oak in the valley. This tree sports two different leaf forms with young foliage having spiky edges and older foliage having smooth edges. Though similar to its cousin the coast live oak, the interior live oak is better suited to our extremely hot summers.