Extension Service Garden Hints

Native shrubs can be leafy, evergreen and drought tolerant

Water-wise shrub and state flower Oregon grape. Photo courtesy of Bureau of Land Management.

CORVALLIS, Ore. – Winter is a great time to study possibilities for new landscape plants that will add structure and character to the property around your home.

With its pattern of wet winters and dry summers, most of western Oregon is well-suited for the “waterwise” approach to gardening, sometimes termed Mediterranean gardening. Even in other parts of the state that aren’t quite as wet in the winter, such as central Oregon, most of the precipitation falls in the winter.

Mediterranean or waterwise gardening relies on the use of plants that are adapted to storing water through the winter and surviving through the summer with little or no irrigation, conserving both water and labor. Native evergreen shrubs are a good place to start, says Oregon State University Extension Service native plant expert Linda McMahan.

“Native plants are already adapted to our regional pattern of wet and dry seasons,” explained McMahan.

“Adding any of these or other low-water evergreens to your garden can create more year-round interest. Plus there’s the bonus of supplying shelter and food for our native birds and other wildlife.”

Oregon grape (Mahonia aquifolium) is native to the west coast from British Columbia to northern California west of the Cascades. With shiny dark green leaves that look like holly, it grows to six feet or more. Several of these spiny leafed shrubs can be planted together and pruned as a hedge. Since the leaves are prickly, don’t plant it where you’re likely to brush against it accidentally, warns McMahan. Bees love to visit the bright yellow flowers and the bluish-purple berries are a favorite for birds.

Oregon boxwood (Paxistima myrsinites) will likely survive Willamette Valley summers with little to no summer watering if it’s shaded during the hottest part of the day. With dark green, shiny leaves, its growth habit varies from low-growing to upright. But be careful to provide enough water for this species during its first one to two years of establishment, says McMahan.

Arbutus menziesii, our native madrone, is valued as unique to the Pacific Northwest. It is difficult to transplant because of its reliance on fungal hyphae (which, together with the plant roots, form a system called mycorrizae.) If you’re lucky enough to have a madrone in your garden already, you might want to use it as a focal point in your garden if you plan to move toward a Mediterranean approach, suggests McMahan.

A close relative to madrone, but native to southern Europe, the smaller Arbutus unedo (strawberry tree) has dark green leaves and reddish bark. Its red berries are especially attractive in late summer through fall. As a popular lawn and garden tree in California, it will also do well in western Oregon. Grown alone as a tree, it can reach about 30 feet. Or several can be planted close together and pruned as a hedge or screen.

Similar in appearance to Arbutus, manzanitas (Arctostaphylos) are a large group of evergreen shrubs native to western North America. Like Arbutus they have shiny dark green leaves and twisted branches with reddish bark. One of the most popular varieties is kinnikinnick (A. uva-ursi). With small, shiny, dark green leaves, it forms a low-growing dense mat up to 15 feet across. It has small white or pink flowers in the spring followed by red berries. There are several cultivars of kinnikinnick that have been developed for garden use. Some of them, like ‘Vancouver Jade’ and ‘Pt. Reyes’ were selected from western coastal sites.

Native to dry, open, rocky areas in the Pacific Northwest and in much of the rest of the world, common juniper (Juniperus communis) is a conifer with stiff needle-like leaves and purple berries. Common juniper tends to have sparse foliage; cultivars of juniper with denser foliage are available. Juniper needs good drainage and very little if any summer irrigation. Too much moisture is likely to cause junipers to fail.

Some evergreens that are native to Mediterranean climates, like Cistus, actually grow better without summer water than with it. Sun-loving and hardy, there are Cistus varieties from dwarf to six feet tall, with blooms from red to pink to white, blooming from May into late fall, often with gray green foliage. Cistus grows well in poor but well drained soil.

You might not think of Rosemary (Rosmarinus), as a shrub, but botanically it is one, says McMahan. The familiar culinary herb is another evergreen Mediterranean native. It comes in varying forms and heights, from small and rounded, to prostrate, to upright and 6 feet. Like Cistus, it’s sun-loving, adapted to poor soils, doesn’t appreciate extra water and requires good drainage.

For gardeners in central Oregon, the Oregon grape, manzanita, kinnickinnick, common juniper and hardier varieties of juniper will work best, says Amy Jo Detweiler, OSU Extension horticulturist in central Oregon.

By: Davi Richards, Carol Savonen
Source: Linda McMahan, Amy Jo Detweiler

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