Most Willamette Valley gardeners know the popular native groundcover kinnikinnick (Arctostaphylos uva-ursi). Less familiar are larger members of the same genus known as manzanita. I fell in love with manzanitas when I visited a botanic garden in the Berkeley hills, where I saw mature specimens of several California species and could really appreciate the stems and bark that are their most striking feature.
To quote Paul Bonine, Portland nurseryman and manzanita lover: “Smooth and muscular trunks and branches twist and turn with the illusion of motion. In most species, the thin bark buckles and splits, rolls up into ribbons and then exfoliates in early summer.”
These distinctive members of the heath and rhododendron family occur naturally from Mexico to Canada. They have an interesting lean, arid look, with stiff, widely spaced leaves that vary in color from green to gray. The leaves are oriented so as to minimize the sunlight that falls on their surface (a strategy to reduce moisture loss) which contributes to the plants’ very special appearance. Small pink or white bell-shaped flowers, similar to those of heather or salal, appear in late winter or early spring. They are followed by colorful small fruits that may be orange, brown or red. Manzanita is Spanish for little apple, which the fruits resemble. Bees love the flowers, and birds enjoy the fruit.
Bonine and Greg Shepherd operate Xera Plants, a wholesale nursery well known to Pacific Northwest plant buffs. Their mission is to familiarize gardeners with unusual plants that are adapted to our wet winters and dry summers. A couple of years ago they opened a retail store in Portland, and it has proved wildly popular. Their inventory contains many native plants along with cool looking non-natives, some from the southern hemisphere. Many are their own introductions, and all are grown using organic methods at Xera’s nursery.
Last year, Bonine addressed the Willamette Valley Hardy Plant Group about plants he believes should be more widely used. Manzanitas have long been regarded as finicky in our region, perhaps, he surmised, because they do not take well to gardens with regular summer irrigation. Without summer watering, Bonine argued, they are among the easiest and most handsome shrubs one can grow. He particularly recommended the many cultivars and species from northern California, which have proved surprisingly tolerant of winter cold and more adaptable to gardens than manzanitas native to Oregon and Washington.
In general, manzanitas do best in acidic, well-drained, un-amended mineral soils, on slopes with full sun, good air circulation, little or no summer irrigation and no fertilizer. Overly rich soils often result in too rapid growth, making the plants vulnerable to wind rock and root rot. Of particular interest to Valley gardeners was Bonine’s claim that some manzanitas, once established on slopes with no summer irrigation, will tolerate clay soil. Varieties he recommends for clay include “Howard McMinn,” “Martha Ewan” and “John Dourley.” Conversely, in very well-drained situations, some varieties will tolerate occasional irrigation.
Mulch should be a slowly degrading material such as “open” crushed rock, wood chunks or coarse bark, not compost. “Anything that increases organic content of the soil will reduce the hardiness of manzanita,” Bonine said. He also stressed that, like any plant, manzanitas need watering until they are established and “can take weekly irrigation until they begin to grow in earnest, then you can taper off. Eventually, most are best with no water during the warm months and can handle the driest of years with no visible stress.” Yes, that includes last summer. Janet and Alan Butler, who live on Jefferson Street in Eugene, have three 10 to 14-year-old manzanitas on a west-facing bank. “We do not water them,” Alan told me. “Unlike a lot of plants, they thrived during last years’ drought.”
It’s best to grow manzanita with other drought-tolerant plants, like Oregon grape and ceanothus. Many suggestions for companion planting can be found at xeraplants.com. Be sure to give your manzanitas plenty of space. Some varieties grow quite large, and they won’t tolerate heavy pruning. You may tip-prune young plants to encourage shapeliness, but branches that have begun to shed bark won’t re-sprout. As a specimen grows tall, limb up to expose the trunk, to improve air circulation and to better admire the stems. You can then under-plant with summer dormant bulbs and small perennials that share the same cultural requirements.
Xera Plants retail store will open for this season on Feb. 4. Hours are Thursday-Sunday, 10 am to 5 pm (6 pm after March 1) The store is located at 1114 S.E. Clay St., Portland, (503) 236-8563.
Closer to home, Doak Creek Native Plant Nursery (open by appointment, 484-9206) lists three varieties of manzanita, including “Howard McMinn.”