OAK TREES – TREASURE OF THE FOOTHILLS

by Jim Beemer, UCCE Master Gardener Emeritus, El Dorado County

December 1999

Just about everybody likes and admires oak trees. In most parts of the foothills they are our most common native tree. Most oaks regenerate by having their acorns scattered by birds and squirrels. They then sprout with the rains and grow very slowly. They also need sunlight. This may have worked fine when the ground was covered by original native grasses, which were primarily “bunch” grasses. Now some oaks may be in trouble in local areas because of competition from the introduced grasses and weeds which can form a solid mat, excluding the sunlight from our poor little acorns and preventing their growth.

But you can raise the oaks on your property very easily. Just collect the acorns and either plant in the ground, covering them with an inch or so of soil, or let them sprout in a pot and transplant immediately after sprouting.

To help you decide which oaks to plant, visit the El Dorado County Historical Museum at 104 Placerville Drive (in front of the fairgrounds). Along the fence in front, to the northwest of the museum building, are eight specimen oaks which I planted as acorns about 1989. All are labeled. Six are native to this county and two are beautiful exotics which do well in our area. Maybe in years to come one of these will replace the “beer tree” at the fairgrounds.

NATIVES FROM THIS AREA
Black Oak	Quercus kellogii
Valley White Oak	Quercus lobata
Interior Live Oak	Quercus wizlezinii
Canyon Live Oak (Golden Cup Oak)	Quercus crysolepsis
Blue Oak	Quercus douglasii
Oracle Oak	Quercus morehus
NATIVE TO COASTAL CALIFORNIA
Coast Live Oak	Quercus agrifolia
EXOTIC – NATIVE TO SPAIN AND PORTUGAL
Cork Oak (cork bark is clearly evident)	Quercus suber

You can also do things on your property to provide the best growing environment for your existing oaks. Actually very little work is needed, and in some cases, the less the better. Pruning, watering and fertilization are rarely required. Mature oaks do not require pruning, except perhaps to remove dead, weakened, diseased or dangerous branches. The native oaks are adapted to dry summer conditions. So, irrigation during the summer can cause significant problems for mature oaks and is to be avoided, particularly near the base of the tree. If the winter season is unusually dry, a supplemental watering in the early spring can complement natural rainfall. Water deeply in the outer two-thirds of the root zone. Healthy mature oaks under natural conditions do not require supplemental fertilization. But when the oak exhibits disease or stress, or when its natural fertilizer supply (the leaf drop and organic litter that decomposes under the canopy) is removed, supplemental feeding may be beneficial.

For more information on this subject or any garden question, contact the El Dorado County Master Gardeners, 621-5512, Monday through Friday 9:00 am to noon, or visit the office during those hours at 311 Fair Lane, Placerville.