Give Western Oaks a Chance!
Hey there fellow plant enthusiasts! I've been thinking, why the heck aren't we planting more western oaks in Spokane? I've scoured all the suggested plant and tree lists put out by the city, county and universities for our area, and all the oaks listed are native to the moist temperate regions of eastern North America, the Midwest, or east Asia. While those oaks are beautiful, and many seem quite happy here, it seems like such a missed opportunity to not incorporate oaks that are native to our side of the continent into our gardens. These bad boys are naturally adapted to drier conditions and hot summers, have superior foliage, and offer so much variety. The west offers everything from the evergreen shade-loving deer oak (Q. sadleriana) to the Sonoran scrub oak (Q. turbinella) that looks like a holly but thrives in hot gravelly locations, to the massive Black Oak (Q. kelloggii), which is one of the most majestic trees you will find anywhere.
So, what's the deal? Why aren't western oaks more popular? My guess is a lack of familiarity. The horticultural industry has historically focused on catering to eastern gardeners (it's a much larger market, let's be real), and the plants that grow well there. The rest of us are expected to amend our soil and irrigate heavily to recreate those conditions. Because of this eastern focus, western oaks (and western plants in general) have not received as much attention, experimentation, mass cultivation, etc. from large commercial growers. Therefore, there are fewer plants available, not as many named cultivars, and less testing of these plants in regards to hardiness, cultural preferences, etc. This lack of widespread cultivation seems to cause many western natives to be designated as less hardy than they actually are. For instance, Ceanothus velutinus, despite growing all over northern Spokane County, is frequently cited as only hardy to zones 7! In the oak world, Quercus garryana, or Garry Oak, is often considered to be quite tender because it's most typically associated with mild areas west of the Cascades. However, these oaks once ranged much deeper into eastern Washington, but 100+ years of fire suppression has allowed conifers to out-compete them for territory. Despite this, Garry oaks are still found in frigid locations, such as Satus Pass, between Goldendale and Yakima. It's also worth considering that these oaks can live 400-500 years, meaning the oldest specimens date to the end of the Little Ice Age, when even temperate parts of the Northwest were quite a bit colder than they are today.
If you're interested in adding some western oak flavor to your landscape, here's a list of some that are currently available at Floralia:
Quercus turbinella, an evergreen small tree or large shrub with spiky holly-like leaves.
Quercus undulata, with lots of genetic diversity, each plant seems to have a slightly different leaf shape and size, making it easy to find a personal favorite. Also grows into a small tree or large shrub
Quercus durata, with thick leathery leaves that are glossy on top with silvery fuzz beneath, it's evergreen and growsas a shrub
Quercus chrysolepis, the northernmost naturally occurring live oak with thick, dark glossy green leaves with golden fuzzy undersides. Grows into a very beautiful medium sized tree
Quercus kelloggii, the largest western oak, grows up to 2 ft. annually and is long-lived
Quercus garryana, the only oak native to Washington, with a beautiful form. It is slow growing for the first few years, but then gradually picks up steam. With sufficient water it grows into a grand old tree, otherwise it settles for being a lovely shrub.
Quercus gambelii, leaves have a classic oak shape. This can be a medium sized tree with sufficient water, or a lovely shrub in dry locations.