Guide to Growing California Oaks

Introduction

There are more than 25 species, varieties, and natural hybrids of oaks native to California.  Before Europeans and Americans settled in California, oak woodlands were much more extensive than they are today.  Harvesting for fuel, clearing for agriculture, rangeland "improvement", and urban development have eliminated oak woodlands from much of their former range. Especially at low elevations and in areas with low rainfall, many oak woodlands have been converted to annual grasslands dominated by introduced grasses. Stringers of oaks along creeks and skeleton oaks on grassy hillsides sometimes provide the only hints of former oak woodlands.

Losses due to clearing for urbanization and agriculture have been compounded by regeneration failure within many existing stands. Sapling populations in many oak woodlands are insufficient to offset mortality of older trees, leading to a gradual conversion of oak woodland to oak savanna and finally to annual grassland. Suppression of regeneration in areas that would otherwise be suitable for oak growth seems to be a recent phenomenon (within the past 60 to 80 years), and is in many cases due to long-term livestock grazing. In many woodlands that have been impacted by long-term grazing, the degradation of the ecosystem is so profound that oak woodland vegetation may not recover for many decades after grazing is eliminated, if it recovers at all.

Oak reproduction problems in woodlands and savannas used as livestock range usually do not extend to horticultural situations. Besides being fairly easy to grow in cultivation, many California oaks volunteer readily in horticultural settings such as flower beds, shrub plantings, and lawns. These horticultural environments are safe sites for oak reproduction:  favorable environments that may differ substantially from adjacent oak woodlands located no more than a short distance away. The key to restoring oaks to their former range lies in recreating safe sites for oak reproduction.

In these pages, we have described specific techniques that can be used to help reestablish oaks in areas where they once grew.  To establish new oaks, we need to ensure that:

• acorns are planted into favorable seed beds,
• seedlings have the proper environmental conditions needed for early growth and survival, including adequate moisture and in some cases shading;
• seedlings are protected from plant eaters (herbivores) and other damaging agents (including fires, mowers, and herbicides)

Depending on site conditions and the species involved, oak growth can be fairly rapid or agonizingly slow.  However, nothing grows slower than the trees that are never planted.  So, how do you do it?  Follow the links for specific tips.