Blue Oak

Quercus douglasii

Blue Oak

The Blue Oak is one of the toughest of our native oaks and  thrives on hot, dry, or rocky locations. It’s blue-green leaves reflect the sun, conserving water for the 5-7 months of the dry season. Its blue-ish leaves, wide-spreading shape, deep roots and picturesque branches make it easy to spot in open space preserves. Blue Oaks tend to grow slowly and live a long time, several hundred years is not uncommon. But they cannot handle  frequent summer irrigation and lawn around its roots. Our soils have a fungus that is kept in check by dry summers. But wet soils during the summer invigorates the fungus which attacks and weakens or kills the tree. Keep your Blue Oak healthy by irrigating infrequently during the summer and putting a thick layer of mulch under the canopy to keep the soil cool.

Height: 35-50 feet
Spread: 40-70 feet
Growth Rate: Slow to Moderate

Irrigation needs: very low
Fall Color: None
Flowers: inconspicuous catkins
Fruit: acorns

Planting Distances
Foundation: 20 feet
Drives/Patios: 6 feet
Fence: 6 feet
Small trees: 30 feet