The Ultimate Shrub



Arctostaphylos densiflora ‘Howard McMinn’
Photo courtesy of HortMag.com

 “Arctostaphylos is the ultimate shrub of the west,” declared Paul Bonin, co-owner of wholesale nursery Xera Plants, at an early November Hardy Plant Society of Oregon Gen(i)us presentation. Arctostaphylos is better known to most gardeners as Manzanita.

According to Bonine, there are 60 species of Arctostaphylos native to the United States, at least 11 of which are native to Oregon. Apparently, they are rather free in their reproductive habits, which results in natural inter-species crosses making parentage difficult to track at times. Native habitat spreads from British Columbia to Baja, Mexico. Related to rhododendron, they take the form of evergreen small trees, large or small shrubs and groundcovers. Kinnikinnick is a well-known groundcover form.

Bark is often the initial allure. “It’s a conundrum why they aren’t used more in our gardens,” Bonine said during his presentation. “They grow in lean clay soils and don’t like summer water. In fact, they can be killed with too much love. They are related to the rhododendron, yet are easier to grow.” Most prefer full sun though some tolerate light shade.

Bonine wants us to think beyond the admittedly beautiful bark and recognize the attraction of the distinctive, “spectacular” upturned leaves. They also offer bell-shaped winter-blooming flowers followed by small fruit. A special favorite of Paul’s? A. densiflora ‘Howard McMinn’. He declares it “the most beautiful shrub ever.” And it’s cold hardy to 0°F (with slight leaf damage), grows to 6 ft. tall and wide and is covered in pink-turning to-white flowers in late winter. Xera Plants’ Web site says it takes irrigation better than other varieties.

Natives can be challenging to grow in the nursery environment, particularly in containers. Apparently, Oregon’s native Arctostaphylos are no exception. In the home garden, according to Bonine, the opposite is true if planted in the right place. They need good circulation as they are prone to black spot and lean (unamended) soil. Tip pruning can control growth and shape; however, growth won’t regenerate from woody stems and they bloom on wood from the previous year. Pruning “up” shows off the beautiful branching and bark and also keeps water and mud from back splashing leaves, which can cause fungal disease. A coarse mulch—not compost!—also minimizes splashing.

Other noteworthy compact Arctostaphylos varieties:

• A. auriculata ‘Diablo Blush’ is a compact 3 ft. x 3.5 ft. shrub with pink late-winter flowers.
  
• A. ‘Sunset’ offers orange-tinted new foliage, early spring flowers and a 4 ft. tall x 6 ft. wide growth habit.
  
• A. x ‘Greensphere’ grows to only 2 ft. x 2 ft. in 10 years. New growth is tinted vivid orange and tints again in cool weather.