Quercus agrifolia or
Coast Live Oak has a pronounced effect on the way we landscape. The
Coast Live Oak is protected by numerous city and county ordinances often
providing conditions for trimming and removal of trees. Most often
if you want to cut something more than 4" you probably need a
permit. The Coast Live Oak has a lifetime similar to ours.
Quercus agrifolia grows rapidly during the first 30 years of its life,
often attaining its mature height. If conditions are good
Quercus agrifolia will continue to grow an ever larger trunk for the next 40
years though the top of the tree will not increase much during this middle
aged period and may thin. As the trees age, much like us, it is an ever more
difficult battle to keep up with what we could once do. The Coast
Live Oak rarely makes it much past the Century mark. It is
interesting seeing early California Mission photos and no oaks, since they
dominate the landscapes around the missions now. A map of where
Quercus agrifolia grows closely matches a population density map of where
we live, more of us along the coast with some scattered into warmer inland
locations and below 5000 feet. Quercus agrifolia grows from
streambeds to north facing slopes and out in full sun where soil
conditions are more prime. The Coast Live Oak is abundantly fruitful
from seed. Quercus agrifolia is a host for the California
Sister Butterfly. Changing from a dry natural rainfall regime to an
irrigated landscape is really hard on the trees. Changing the grade
around the trees, either up or down is really hard on the trees and will
significantly reduce their lifespan. Fertilizing nearby plants often
kills the naturally associated fungus on the roots of the trees allowing
non-native fungus free rein. The roots of the trees extend well past the
shade of the foliage with the greatest density of roots in the top 3 feet
of the soil. Quercus agrifolia drops a lot of debris. This
self mulching creates a cool loose soil that maintains moisture
well. Attempting to mimic this with woodchip mulch can cause
problems if the mulch rests against the trunk of the tree. I have
seen some pretty big Coast Live Oak trees get moved, sometimes with
moderate success. Quercus agrifolia has been cut for hedges, it
works surprisingly well for this. The Coast Live Oak makes for an interesting
bristly bonsai. Lawns under oaks work fine, if the lawn was there
first. If not watering the lawn will dramatically shorten the
lifespan of the tree. All that debris, your pool man would hate you
if you put a pool by this tree or regularly thank you for insuring his
continued regular employment, or both. I have often heard the line from a
tree trimmer on a budget that he will only be around once every 5 years,
so a hard pruning is a good idea for the safety of the landscape. I don't think so. If the trunks of
the Coast Live Oak are exposed to sunlight they sprout an amazing number
of small shoots. If these last long enough and turn into branches
they are poorly attached and often fall off at inopportune times, never
the good thing for shiny cars or wandering gardeners. In the
end the Coast Live Oaks can be spectacular if well maintained, but they
sure make us work hard to keep them healthy. For a suitable list of
plants for planting in the shade of oaks see our Dry
Shade Garden List
High resolution images
of Quercus agrifolia are available
