Quercus douglasii
Blue Oak
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Blue Oak (Quercus douglasii) - Description
Quercus douglasii, the Blue Oak, is an oak in the white oak section of the genus, Quercus sect. Quercus. It is endemic to California and is found in foothills surrounding the Central Valley of California and certain locations in the California Coast Ranges, USA. It is also sometimes known as the Mountain Oak, and occasionally the Iron Oak.
Blue Oak (Quercus douglasii) - Blooming
The flowers of Oaks are inconspicuous, but they eventually evolve into acorns of many different shapes and sizes.
Blue Oak (Quercus douglasii) - Growth
Since Quercus is such a large genus of trees and shrubs, there are many growth needs. It is best to understand where your Oak tree is native to and try to emulate that climate and watering regime.
Blue Oak (Quercus douglasii) - Planting
Oak trees can be planted from acorns or transplanted by sapling. Select several fallen acorns that are shiny and plump. Remove the caps. Dig a hole 6 inches deep and 6 inches wide. Refill the hole until you can plant all of the acorns on their sides and still have 1 inch of soil on top of them. When the acorns have germinated, select the strongest seedling and weed out any other acorns that may have germinated. This procedure allows for better chances of survival since birds may pick off some acorns. For transplants, it is important to keep the sapling watered for up to 6 weeks while the roots can reestablish themselves. Best time to transplant is in the fall or winter.
Blue Oak (Quercus douglasii) - Pest
Oak trees and their acorns provide food for a complex web of insects and animals. Since most Oak trees are fairly large, handheld sprayers available to home gardeners may be ineffective. Consulting with an arborist may be your best bet. Oak moth caterpillars can be a problem if heavy infestations occur for consecutive years. Oak root fungus (Armillaria) can cause a problem, but can be kept in check by warm dry summers and cool winters. More recently a fungus has been recognized (Phytophthera ramorum) that infects and can kill Oak trees. The subsequent disease is known as Sudden Oak Death because few symptoms are outwardly visible before the death of the tree occurs. The disease causing fungus has many host plants that it may or may not kill. Its spores are spread via wind and splashing of rain drops. One particular host plant that seems to have a deadly relationship with Coast Live Oaks is the California Bay Laurel (Umbellularia californica).
Blue Oak (Quercus douglasii) - Interesting facts
The genus name Quercus is derived from the agricultural product that is harvested from one species, Quercus suber, aka the Cork Oak. The cork of the Cork Oak is relatively thick and can be stripped with little detrimental effect to the tree. Additionally, the species name "suber" is derived from the compound that is present in cork and gives it its special qualities. That compound is called suberin.
Blue Oak (Quercus douglasii) - Soil and irrigation
Since there are so many Oaks from many different parts of the world, it is best to try to emulate your Oak's native precipitation. For example: Q. agrifolia is native to Southern California and requires no irrigation in the summer and may require some irrigation in the winter if the winter months are absent of any precipitation for extended periods of time.
