Arctostaphylos — Manzanita Shrubs
Of all of the California native plants suitable for garden use, perhaps no genus is as diverse and adaptable as Arctostaphylos, commonly called manzanita. Members of the same family (Ericaceae) as the madrones which grace many parts of the county, manzanitas come in all shapes and sizes, from small trees to surface-hugging ground covers.
There are dozens of different manzanitas in the wild in California and the Pacific Northwest and even more named cultivars. They can be found in a wide range of habitat, from coastal scrub to mountain bluffs to pine forests. Not surprisingly, given their large number and the diverse habitats in which they are found, there are manzanitas for almost every garden situation. However, because cultivation requirements vary, it is important to carefully select a manzanita with the specifics of every garden environment in mind.
Although there is much variety within the genus, almost all manzanitas have dramatic branching structure, bark that ranges from cinnamon to mahogany, evergreen foliage, winter blossoms and small fruits. (Manzanita means “little apple” in Spanish.) On the larger plants the branching structure is a focal point in itself, its impact dwarfing that of the leaves or flowers. Even the small and medium-sized shrubs can provide structure and drama in the garden, especially when lower side branches are pruned off main stems to expose smooth, colorful wood.
Because manzanitas bloom prolifically in winter when most garden plants do not, adding them to the landscape will draw many nectar-seekers such as hummingbirds and honey bees. The fruits are also food for a diverse group of wildlife, including quail.
In deciding which manzanita shrub to plant, first determine its purpose in the landscape: What is needed? A tree, a shrub, or a groundcover? Then assess the site: Is it in full sun? How much water will it receive and what is the drainage like? Is there much competition from other plants? While most manzanitas prefer full sun, low water and good drainage, some are more adaptable than others and some tolerate garden conditions much better than others.
Sonoma County native Arctostaphylos densiflora ‘Howard McMinn’ (named after the botanist and author) won a well-deserved award of merit from the California Horticultural Society in 1956 and is a shrub especially suited to garden use anywhere in Sonoma County. It can grow taller but is most often seen at 4- 5 ft. by 5ft. and can be kept there if needed with periodic shearing. It will tolerate heavy soil, summer irrigation and some shade. It will even tolerate overhead watering.
What makes ‘Howard McMinn’ particularly special is that in addition to being extremely good-natured, it is also extremely handsome with glossy green leaves, twisting cinnamon branches and copious flowers in late winter. Its growth habit naturally opens up as it ages and with a little judicious pruning of small twigs and dead inner branches, it matures into a dramatic, easy-going shrub within a few years. It combines well with other natives but also shines when paired with Mediterranean-climate species and other garden choices. Few other manzanita shrubs are as garden-worthy as ‘Howard McMinn.’
Arctostaphylos bakeri ‘Louis Edmonds’ is nearly as garden-worthy as ‘Howard McMinn.’ It, too, reaches 5 ft. or so, bears deep pink flowers in early spring, and withstands moderate garden irrigation.
The hybrid ‘Sunset’ also mounds to 4-5 ft. and as wide and features colorful, coppery-red new foliage. ‘Sentinel’ has a more upright than mounding structure and flowers more prolifically. It may be trained into either a mounding or treelike form, requires fast-draining conditions, and prefers sandy sites although it can be grown in heavier soil.
Most manzanitas are largely trouble-free once established. They are susceptible to a few fungal pathogens, some of which cause branch die-back and others leaf-spot. The wetter and more humid a micro-climate, the more likely it is for plants to develop these problems. Good air circulation is especially important in coastal locations. Cutting off affected branches and cleaning up fallen leaves as well as avoiding overhead irrigation helps keep the conditions in check.
Manzanitas are also afflicted with manzanita leafgall aphids that produce red galls on new leaf growth. Aphids live inside the pod-shaped galls that eventually die along with the entire leaf. Smooth-leaved species such as ‘Howard McMinn’ are more susceptible to leaf gall than those with hairy leaves. The gall is not harmful to plants, just a bit unsightly for a while. Affected branch tips may be trimmed off.
Leafgall is most common in plants that are producing new growth out of season, usually due to an abundance of water, so cutting back on irrigation helps. Because galls appear on new leaves, avoid applying fertilizers and pruning, both of which stimulate new leaf production.