Arctostaphylos – Manzanita
Ultimate shrub of the west
No other shrub is more symbolic of the Pacific Coast than Manzanita. From Baja to Canada one species or many are native from the coast to the mountains. They thrive where winters are moist and cool and summers are dry. Dramatic showy bark and familiar flowers make them great transitional shrubs from cultivated borders to wild areas. In the Pacific Northwest they are great echos for Madrones and are at home in a variety of landscapes. As with Madrones they are members of the Erica family, the Ericaceae.
Summer drought adapted
Pink to white urn-shaped flowers appear for a long time in winter to spring and followed by copious amounts of small shiny fruit. Manzanita is Spanish for “little apple” to which the fruit resemble. Edible for animals they are almost all mealy and too dry for the human palette. One reason they are such striking shrubs is that they hold their evergreen leaves perpendicular to the sun- an adaptation to avoid moisture loss. The myth that Manzanitas are difficult to cultivate most likely comes from the fact that they do not take well to regular summer irrigation. In a garden where summer watering is non-existent they are among the easiest and most handsome shrubs one can grow. They do best in acid soil on slopes with full sun and good air circulation with no summer irrigation.
Manzanitas in containers
Arctostaphylos make excellent container subjects as long as the plant is not subject to overwatering. Many varieties will live happily in pots for years and will eventually develop gnarled, bonsai-like characteristics. Water when dry and in early spring apply a handful of all organic fertilizer around the roots. Arctostaphylos have many, many wiry roots meant to extract nutrients from a wide zone. Remember this when containerizing them. Large species can fill a pot with roots in just a year or two. Again, this requires annual fertilizer applications to maintain good health. Also, the restricted roots in containers means that the plant will grow quite a bit more reservedly than when it can stretch out in the ground. Rich potting soil that you would use for annuals is ideal. Arctostaphylos are surprisingly heavy feeders in a container.
Pruning
Striking exfoliating bark is one of the hallmarks of this genus and pruning Arctostaphylos to showcase this bark is very simple. To maintain a compact plant or to increase density simply tip prune new growth after it has emerged- after flowering has ended. Just tip off the few leaves at the end of each stem. For more radical pruning its important to understand that you can prune on current growth (with leaves) and it will resprout. Older wood without leaves (and probably peeling bark) will NOT sprout from dormant buds. There are none. This comes into play 3-4 years after establishment. Most pruning is done to eliminate dead or useless twigs around the base of the plant. To “lift it up” and expose the lovely peeling stems/trunk you can remove these branches at any time. This also importantly improves air circulation. Make these cuts carefully. Make a cut stand back and evaluate before you make another. The majority of specimens benefit from this treatment in the long run. Use sharp and powerful secateurs as the wood is very strong. To limit the size of a Manzanita see the first method. So- you can limit size and increase density by pruning into green (between leaves). If you prune leafless wood there will be NO re-sprouting from that wood. Its permanent. It is surmised that the trunks and stems exfoliate to repel moss and lichen development- important where winters are moist.
Planting and soils
Arctostaphylos are tolerant to a LOT of soil types. The one variable is that they all dry completely in summer. Avoid all areas where there is standing water at any time of the year. The best way to prepare the soil for planting is to dig a LARGE area by flipping the soil and incorporating oxygen. This also helps water and roots penetrate the surrounding area. Arctostaphylos in the ground have many, many wiry roots that spread out and extract nutrients from a large area. Since they are so efficient they require no supplemental fertilizer in the ground. (See containerized plants above for fertilization instructions). Arctostaphylos that are in soil that is too fertile react in several ways. They can die of root pathogens, or they can grow prodigiously fast and huge and this in turn shortens their life span. It can also substantially lessen their hardiness to winter cold. Average, un-amended native soils are ideal for their culture.
Mulch with bark
Avoid amendments, mulch with bark, NOT COMPOST. Mud that splashes on lower leaves in winter/during irrigation can result in black spot (fungal disease) on the lowest leaves. Coarse bark mulch prevents mud splash as well as inhibiting weeds. Newly planted Manzanitas can take weekly irrigation until they begin to grow in earnest- then taper off. Eventually, they are best with no water during the warm months and can handle the driest of years with no visible stress. Manzanitas bloom on wood from the previous year. They may be tip pruned to limit size and as they age they can be limbed up to reveal the striking bark. This also helps ensure good air circulation which they very much appreciate. All are evergreen (of course).
The best size to plant
We grow Manzanitas in three different sizes. One gallon, two gallon and five gallons. We heartily encourage you to plant in smaller sizes. Arctostaphylos especially larger growing varieties grow extremely fast when established. Planting a smaller size not only ensures greater root development it reduces the chances that a young plant is rocked by strong winds which can tear the roots. Starting with a smaller size means plants grow incrementally and the survival rate is much greater. We offer healthy, well rooted plants ready for immediate planting. Remember to mulch and then water your manzanita weekly until it starts to grow in earnest. Then taper off.
Trouble shooting Manzanitas
Manzanita should be very well rooted before planting. That does not mean the plant should be root bound. Instead the rootball when up ended will solidly hold the soil. Also, a plant should never be unstable in a pot. This can lead to unstable growth and the plant can rock and eventually the roots tear and the plant fails. Look for plants that are well branched from the beginning. We prune our Manzanitas as small plants to both stabilize the amount of root growth to top growth so that rocking is seldom a problem. We have high standards for our Manzanitas and we hope that you do too. Often Arctostaphylos are relegated to the driest, poorest substrates, even in nursery containers. The truth is they are extraordinarily efficient at gleaning nutrients from the soil. They can literally suck the nutrients out of a pot. (See fertilization for containerized plants). Fungal spots on Manzanita are often a deficiency in nutrients which can be brought about by poor air circulation and overly wet summer soils.. A sick plant will start to have black dots on interior lowers leaves and then they will turn yellow on the inside of the shrub. On the other hand, over irrigated Manzanitas fail fast and completely. They turn an ominous light tan green color and its all over- kaput. Remember to mulch newly installed manzanitas with coarse bark after planting. Again, water once a week until you see good new growth then taper off. The soil should dry completely between irrigation if planting during the dry season.
Manzanitas throughout Oregon
Arctostaphylos total more than 60 species all native to the western United States, Canada, and Mexico with one species A. uva-ursi Kinnick KInnick a circumpolar species. In Oregon they are found extensively in shrub communities throughout the state. On the west side the most common variety is Hairy Manzanita Arctostaphylos columbiana. Its extensive in the Coast Range, Cascade foothills and even the eastern Columbia Gorge. Its famous on the coast for occupying stabilized sand dunes where it accompanies shore pine and other ericaceous plants. In central Oregon the most familiar species is Arctostaphylos patula Green Leaf Manzanita which is famous for its conspicuous orange bark, green foliage, and pink flowers. In the Cascades above 4000′ the predominant species is pine mat manzanita Arctostaphylos nevadensis. In SW oregon there is a cluster of 9 species of Manzanita, part of the extension of the California Floristic Province which ends right at Eugene in the west central part of the state. These and just about all Manzanitas will hybridize if there are others species nearby. These hybrids expand the genus extensively and many of the best garden Manzanitas are hybrids. Oregon species of Manzanita tend to be slightly more difficult to cultivate in gardens. They require great soil drainage, NO SUMMER WATER and great air circulation. Manzanitas are the second most common chaparral plant component in both California and Oregon. Second only to Ceanothus. Arctostaphylos are known as a seral species. They follow disturbance such as fire, logging, even road building. They are often the first woody component to reach these sites. The seed which is widely dispersed by birds can remain dormant for generations awaiting the next disturbance event
Burls
Many Arctostaphylos will develop what are known as burls at the base of the plant. This swollen trunk contains many many dormant buds. This is likely a fire adaptation and assists the plant in regeneration. Not all Manzanitas will develop a burl and it is surprisingly rare in gardens. If a burl does occur the plant may be cut to that base from which it will quickly regrow.
Sonication and native bees
Arctostaphylos rely on native bees for pollination. Introduced European honey bees (Apis mellifera) are NOT adapted to pollinate them. manzanitas are a class of flowering plants that relies on ‘Sonication’ for pollination. The best way to remember this is the other term ‘buzz pollinated’. The shape and structure of the flower is specific to our native bees. They do not enter the flower. Rather they use their bodies to vibrate the flower violently using non-flight muscles. This does two things. It releases the fine pollen which drifts past the pistil and pollinates the plant at the same time it showers the bee who is exposed through the tiny openings in the flower. Great force is generated by the bee, up to 30 G’s and allows the pollen to flow down the stigma and exit the flower. Habitat for our endangered native bees is just another reason we love these important shrubs.
Arctostaphylos are Oregonians
There are 11 distinctly separated species of Manzanita native to Oregon. This is a very Oregon plant and if you include naturally occurring hybrids there are many more than that. The two species native to the Portland area, Arctostaphylos uva-ursi and Arctostaphylos columbiana are no longer present- their habitat destroyed by urbanization. But there are an extraordinary number of species and cultivars from the whole west coast that have proven their worth in our gardens.
Climate Adapted Plants for Gardeners in the PNW
