Extension ServiceManzanitas for Western Oregon Gardens
This article is part of a publication series based on the Northwest Plant Evaluation Program at Oregon State University. This research program has evaluated flowering shrubs for their suitability in landscapes in Western Oregon since 2000. These publications highlight plants that were successfully grown without irrigation in the trials as well as techniques for growing and establishing drought-tolerant plants in the landscape.
The research trial evaluating manzanitas occurred during 2011 to 2019 at OSU’s North Willamette Research and Extension Center in Aurora. The trial compared 75 accessions of manzanitas, which were irrigated only during establishment in the fall of 2011, and were not pruned or fertilized. Information collected about the plants included bloom time, size and cold hardiness. We have selected the top five performing plants for Western Oregon landscapes based on our research and describe them below.
Overview of manzanitas
Arctostaphylos is a genus of woody, evergreen shrubs or small trees collectively known as manzanita which are native primarily to western North America, from southern British Columbia into Mexico. One species, A. uva-ursi, is known as kinnikinnick or bearberry, and is far more widely distributed in temperate northerly areas of North America, Europe and Asia.
The various species are found in a wide range of habitats, from coastal areas to chaparral and mountainous regions. The common name, manzanita, Spanish for “little apple”, refers to the small rounded fruit, which is often green or various shades of red. Because of the wide geographic distribution, the habit of manzanitas varies widely from prostrate, wide-spreading groundcovers to rounded shrubs to small trees. The larger-growing plants often have intricately twisted branches, a structure which may be enhanced by a beautiful, polished, mahogany-like bark.
Although the leaves on all manzanitas are simple, the color and texture vary considerably from the small glossy green leaves of A. uva-ursi, to the large, vertically-orientated leaves of many species from hot climates. Leaf color is often green, but some species and cultivars feature hairy and/or waxy leaves which take on a blue or silvery appearance. In some cases, the new foliage takes on reddish tints which add to the ornamental appeal of the leaves. Flowers are bell-shaped, shades of white or pink and held in dense, drooping clusters that appear in mid- to late winter or earliest spring. Both hummingbirds and bumblebees are attracted to the flowers.
When using manzanitas in the garden, it’s worth considering their typical habitat in nature. They usually occur in poor, but well-drained soils of low nutrient content in summer-dry climates. So, for success, they are best situated in the garden in conditions similar to these with companion plants with comparable needs.
Place them in full sun or at least full afternoon sun. Watering or fertilizing after establishment is discouraged. Pruning requirements vary depending on the growth habit. Prostrate or mounding/spreading forms usually have limited or no pruning requirement. Upright-growing or tree-like forms do benefit from regular aesthetic pruning to enhance the appearance of their branching and attractive bark. Over time, these types develop many twiggy dead growths within the canopy that attract lichen and detract from the structural beauty of the plant. Although tedious, the removal of these twiggy growths can be done once per year and significantly improves the appearance of the plants.
