Arctostaphylos sp.

This has been a horrendous September where I live in Oregon’s beautiful Willamette Valley. Our lush valley has been inundated with smoke from nearby fires in the Cascade Range. Over 1 million acres are ablaze right now as I write this article. The American West is facing an ecological catastrophe fueled by climate change. We have a very long and challenging road ahead of us, and we must find the collective will to actually deal with this problem. These Green Guides that I’ve written for the past three years have been all about recommending plants for our industry that I feel have particular merit and should be grown more widely. This month, I’ve chosen to write about the genus Arctostaphylos, the manzanitas. Many species are both beautiful in the landscape and are adapted to survive fire.

I don’t really know any plants that just won’t burn, though manzanitas are somewhat fire resistant. They don’t burn easily, but their greatest evolutionary advantage lies in the fact they are fire “adapted.” Many species of Arctostaphylos native to the Western United States need fire for their seeds to germinate. About two-thirds of all manzanita species reproduce though obligate seeding, whereby plants do not resprout after a fire and rely only on seeding to regenerate their population. Imagine every adult in a species being wiped out in a catastrophic fire. The species would become extinct if not for the fact that its seeds were left behind by the fire. In fact, the intense heat of the fire cracked open the seed and allowed germination, and thus survival of the species. Obligate seeding allows for a genetically diverse population that is able to adapt and evolve much faster than species that reproduce by resprouting.

The biggest reason we should be growing more manzanitas is that they are beautiful landscape plants. The genus contains groundcover plants, as in the species uva-ursi and its cultivars. It also contains a plethora of beautiful shrub and small tree species. Arctostaphylos species are covered with bell-shaped flowers arranged in clusters in late winter and early spring and provide a good nectar source for early hummingbirds and bees. Many species have attractive reddish bark, adding to their alure as a landscape plant. Among my favorite cultivars is ‘Greensphere’, which has somewhat dense spherical shape and stays under 3 feet tall. I also love the pale, almost white foliage and pink stems of A. silvicola ‘Ghostly’, which grows into a small tree, reaching 8 feet in just five years. There are many other beautiful and garden-worthy varieties to consider. Most West Coast natives are hardy to USDA Zone 7, with a couple even to Zone 6. Colorado natives are Hardy to USDA Zone 4, as in Arctostaphylos x coloradoensis ‘Panchito’.