Sonoma County Master Gardeners Helping Sonoma Gardeners

By Sara Malone, Sonoma County Master Gardener

Of all of the California native plants suitable for garden use, perhaps no genus is as diverse and adaptable as Arctostaphylos, commonly called Manzanitas. 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. All are native to the Western United States, particularly California, and can be found in a wide range of habitat, from coastal scrub to mountain bluffs to pine forests. There are over 90 different kinds of manzanitas in the wild and roughly 140 additional named cultivars. Not surprisingly, given the large number of varieties and the diverse habitats in which they are found, there are manzanitas for almost every garden situation. However, because the cultivation requirements vary, it is important to select varieties carefully, with the specifics of your 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 the lower limbs are pruned off to expose the branches. Because Manzanitas bloom prolifically in winter, when most garden plants do not, adding Manzanitas to your garden will draw many nectar-seekers, such as hummingbirds and honey bees and increase the habitat value of your garden. The fruits are also a food for a diverse group of wildlife, including quail.

With so many varieties to choose from, how do you decide what to plant? First you must determine your landscape purpose – do you need a tree, a shrub, or a groundcover? Then assess the site – is it 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. Armed with your criteria and conditions you can attack the reference materials, or, for a more hands-on experience, visit one of the County nurseries listed at the end of this article for a consultation. We’ll focus on one cultivar as an example, but remember that you have many other choices!

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 Manzanita especially suited to garden use anywhere in the County. It can grow (slowly!) to as much as 8’ but can be kept at about 5’ by 5’ with periodic shearing. It will tolerate heavy soil, summer watering and some shade. It will even tolerate overhead watering! What makes it particularly special is that in addition to being extremely good-natured, it is also extremely handsome – glossy green leaves, twisting cinnamony branches and copious flowers late in Winter. Its growth habit naturally opens up as it ages and with a little judicious pruning of small twigs and dead inner branches, you will have a dramatic, easy-going shrub within a few years. You can plant several together in a clump (allow enough room between them – they can spread up to15’ eventually--plant grasses, annuals or shorter-lived perennials in between) or use them as a hedge. A. ‘Howard McMinn’ combines well with other natives but also shines when paired with Mediterraneans or other garden choices.

‘Howard McMinn’, like most Manzanitas, is largely trouble-free once established. Manzanitas do suffer from a few fungal pathogens, some of which cause branch die-back and others leaf-spot. The wetter and more humid your micro-climate, the more likely your plants will suffer from these problems. Good air circulation is important in coastal locations, especially. 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 Leaf Fold Aphids, which produce red galls on new leaf growth. The aphids live inside the gall which eventually dies, along with the entire leaf. Smooth-leaved Manzanitas such as ‘Howard McMinn’ are more susceptible to leaf gall than hairy-leaved varieties. The gall is not harmful to the plants – just a bit unsightly for a while. You may trim off affected branches. It is most common in plants that are producing new growth out of season, usually due to an abundance of water, so cutting back on water generally helps, too.

Once you’ve experimented with a shrub form like ‘Howard McMinn’, investigate some of the ground covers such as A. edmundsii - ‘Edmunds Manzanita’, especially the Carmel Sur cultivar. This variety performs exceptionally well in gardens, providing a dense, lush carpet within a few years. A. ‘Pacific Mist’, which is taller and rangier, is also a good choice.

We are lucky to have nurseries in the County that focus on native plants and knowledge about them. Be sure to visit Mostly Natives in Tomales (they’re closed for the month of January), Cal Flora in Fulton (reopens January 21) and Buckeye Nursery in Petaluma, all of which specialize in natives.

©Sonoma County Master Gardeners