Pacific Northwest Native Plant Profile: Pacific Madrone (Arbutus menziesii)

Arbutus menziesii bark

Although it looks exotic, Pacific madrone — a beautiful broadleaf evergreen tree with a captivating and distinctive presence that transforms with the seasons — is endemic to the Pacific coast. Its exquisite attributes — fragrant flower clusters, brilliant berries, glossy leaves, twisting branches, rounded crown, and rich cinnamon-red bark that peels from a satin-smooth trunk — please all of our senses. And for the wild ones attracted to this unique gem, its ecological gifts never disappoint.

Madrona (after madroño, the Spanish name for a Mediterranean “strawberry tree”) is the name admirers in Washington give this member of the Ericaceae (heath) family, while those in California and Oregon call it madrone or Pacific madrone. British Columbians simply use the Latin genus name, Arbutus. (The epitaph, menziesii, is named after the naturalist Archibald Menzies, a naturalist for the Vancouver Expedition that explored the Puget Sound region in 1792.)

How it grows
Pacific madrone is a large, long-lived tree that naturally occurs in a climate with mild, wet winters and dry summers, although rainfall varies substantially within its range, from the east coast of Vancouver Island in British Columbia, southward through Washington and Oregon (west of the Cascades) to San Diego County. It is often found on rocky soils and other coarse soils that retain little moisture, including the dry foothills, wooded slopes and canyons of parts of California (at low to mid-elevations); within coastal redwood and mixed-evergreen forests of California and Oregon; on dry ridge tops and slopes at low to mid-elevations along the east side of the Coast Ranges and in the Siskiyou Mountains; on warm, dry, lowland sites west of the Cascades (within Douglas-fir/western hemlock forests or Oregon white oak or tan oak woodlands); and — furthest north — near sea level on rocky bluffs and low elevation slopes. Within mixed hardwood forests — that may or may not have an overstory of conifers — its tolerance to shade varies with age. While madrone seedlings do best in partial shade and young trees can handle quite a bit of shade, tolerance decreases as trees age and for those at the northern end of this species’ range. Older trees need good light to survive and often can be found  growing at an angle, twistily and desperately reaching for the sunlight that helps ensure a long life.

Wildlife value
Wild ones are drawn like a magnet to madrone trees year round. In springtime, lovely creamy white, waxy, urn-shaped blossoms provide nectar for hummingbirds, native bees, and other pollinators.

Arbutus menziesii in flower

 

Clusters of bright red berries — that ripen in autumn and may persist into early winter — feed many bird and mammal species, including American robins, varied thrushes, band-tailed pigeons, cedar waxwings, northern flickers, quail, raccoons,  squirrels, mule deer, and bears.

Arbutus menziesii (fruit)
Habitat is provided for a variety of insects, including echo blue and brown elfin butterfly caterpillars who nibble on leaves and in turn provide dinner for insectivorous birds. Shiny, leathery leaves generally remain on branches for two years, after which they turn from vivid green to burnt orange and settle to the ground where they provide a natural mulch that protects soil microorganisms and little ground-dwelling creatures. Lofty roosting and nesting habitat is also supplied, and live trees with rotting wood offer cavities for insects as well as birds that nest in trees, such as woodpeckers and chickadees. Dead and dying trees provide even more dead wood for cavity nesters and the silent decomposers that function as nature’s recyclers.

Conservation
Unlike other trees, madrone’s fine roots have adapted to search deeply into rock fractures for stored water or “rock moisture,” making it an important plant for stabilizing slopes and cliffs and preventing landslides. In addition, it’s a valuable component of many vegetation types; for example, in mixed conifer forests like Washington’s Coast Range ecoregion (Douglas-fir/western hemlock/madrone), it provides a mid-canopy story, essential for the structural diversity of the forest.

It ought to be preserved for its own sake, for the wildlife that use it, for the ecosystems of which it’s an indelible part, and, needless to say, for those of us who revere its spectacular beauty.

Tragically, the species is currently in decline throughout most of its range, for several reasons. First, sprawling development in its native habitat has stolen many mature specimens. Though tough and drought tolerant (or more precisely, drought dependent), its roots are extremely sensitive to drainage changes, compaction, grade alteration, and other soil disturbance. Because madrone belongs and successfully grows in regional arid soil conditions that many trees cannot, landowners and developers ought to protect and save this tree at all costs.

Under natural conditions, madrone depends on intermittent fires that limit the conifer overstory (typically Douglas-fir trees). Older madrone trees can survive fire and will sprout quickly and profusely afterwards due to carbohydrate reserves within existing roots. In addition, their fruit produces many seeds, which sprout on exposed soil readily after fire. But when humans suppress and prevent natural fires, the prolonged absence of fire and consequential shade—especially on moister sites—may cause madrone trees to die.

Death or damage may be also caused by several pathogens, including a foliar fungus (Nattrassia mangiferae), commonly called “madrone canker,” that reproduces via spores and causes dieback, blackening of branches, and cankers that may spread to the trunk. A root rot, Heterobasidium annosum, can also cause serious damage. Unlike fire, “disease decreases starch accumulation in the root burl, so that declining trees are less able to resprout after the aboveground portion of the tree is killed by disease.” But prevention is possible: Susceptibility to disease is exacerbated by unnatural environmental stresses such as regular summer irrigation and the use of fungicides and fertilizers. Essentially, spores are carried by water, fungicides kill beneficial mycorrhizal fungi (symbiotic associations between the roots of most plants and fungi, which protect roots from pathogens), and studies suggest that increased soil nitrogen disrupts the mycorrhizal associations between beneficial fungi and tree roots, which in turn reduce the supply of micronutrients and water to trees, thereby increasing susceptibility to disease. Madrone trees host a large number of types of mycorrhizal fungi and have been called “a major hub of mycorrhizal fungal diversity and connectivity in mixed evergreen forests” that play a large role in forest regeneration by promoting resilience to disturbance below ground.

Madrone is also affected to a small extent by sudden oak death, a disease caused by a water-borne, fungus-like pathogen, Phytophthora ramorum, which arrived in the U.S. via live plant imports of exotic ornamentals to nurseries; it is increasingly spread by human actions, including climate chaos.

Try it at home
Despite all these threats, a madrone in the wild can live hundreds of years and may grow very large — over 100 feet tall — although in cultivation they rarely exceed 50 feet after many decades. Young trees often grow fast (up to several feet per year), while older trees typically grow at a much slower pace. In the southern, drier and warmer part of its range it grows more slowly and stays smaller.

Supplemental water after establishment is highly detrimental: Madrone cannot tolerate slow drainage, standing water, or regular irrigation during summer, which makes it susceptible to disease (as do fertilizer applications). While it has a bad reputation for being difficult to establish and isn’t for the fussy gardener, knowing what this tree needs and cannot tolerate will help ensure success. In my experience, there are seven essentials to successfully growing this tree:

1. Figure out if it historically occurred in your area. Though it’s not absolutely essential that this species likely grew in your immediate area 200+ years ago — especially since much change has occurred since then — because this tree can’t just be stuck in the ground anywhere, look to nearby natural areas to see if it might have naturally occurring relatives nearby in similar soil. In its northern range, it’s usually found growing on soils derived from glacial sands or till and gravels, while in the southern and middle parts it reportedly grows on soils derived from a variety of materials.

2. Be sure your site has the right conditions: Fast-draining, non-compacted, slightly acidic soil (pH a little less than 7), and a bright location with at least a half day of sun in northerly locations. However, seedlings need partial shade to establish, so if you have mostly sun, shield them from hot afternoon rays until well established. Site plants on a slope or area that’s elevated above the surrounding area to facilitate drainage. In my yard I tried twice to grow one-foot-tall saplings in the lowest part of my yard with sad results, despite digging in extra small rocks and gravel to increase drainage. My third attempt, which I grew myself from seed, I planted atop a short, south-facing slope, again with extra rocks and gravel. I believe that the increased drainage was what was needed; however, the seedling was also very small — only three inches tall! — so that also may have helped. Note: If you live in a very warm, dry area (such as parts of California) be sure to plant this tree on a north-facing slope, rather than in hot, direct sunlight.

3. Start with very small saplings, no more than a foot tall, as older trees do not transplant well. Once they “take,” however, young trees grow quite fast (in my yard, over a foot a year). 

4. Buy plants propagated from source material that originated as close as possible to your site. Using such “local genotypes”  helps ensure that you get plants that are well adapted to your area and preserves the genetic diversity that helps plants (and animals) adapt to changing conditions. Ask growers and nurseries about their sources if you’re unsure.

5. Plant saplings in the fall, just as winter rains begin, since they establish best when they can establish roots first, then put on aboveground biomass. You can plant them in the spring, but you’ll end up worrying about how much or how often to water; during the moist days of autumn you can just let nature decide. Do not add large amounts of organic matter into the soil that could inhibit the moisture-seeking roots from penetrating to mineral soil, and do not add fertilizers that can disrupt the mycorrhizal associations between beneficial fungi and roots. Never apply fungicides or other pesticides.

6. Give them space. To allow them to get to their full and most beautiful form, plant them at least 20 feet apart and at least 25 feet away from tall trees, especially conifers that produce deep shade. Also try to minimize soil compaction, which can be detrimental.

7. Irrigate sparingly, and preferably only during the first summer or two. During my little tree’s first spring and summer it was unusually warm and dry, and I noticed some wilting of leaves on especially warm days. I carefully (and nervously!) watered it with tepid tap water (or rain water I had collected) in the mornings around its base and outwards a few feet, keeping the leaves and stem completely dry. I did this only a couple of times a week when heat was predicted, and by the end of the summer it was in fine shape and had grown well over a foot in height. During the second summer I left it on its own, and when no wilting of leaves occurred it became clear that the little tree was self-sufficient. After another foot of growth was added, I was able to fully exhale. Sometimes a little wilting of leaves isn’t serious: when cooler nighttime temperatures return the tree may bounce back, but you’ll have to be the judge at your particular site.

Baby madrone

Baby Madrone, just 4 months after planting as a 3-inch-tall sapling. [Update, 2023: At around 8 years of age, Ms. Madrone is now nearly 12 feet tall.]

 
Grab a partner
It’s best to match madrones with other species that are compatible below ground—those that have similar needs and mycorrhizal associations and that would naturally occur together in nature (if you already have some non-natives that you want to keep, be sure not to grow any that need summer irrigation nearby). Which native “associated species” you choose depends on what part of the region you live in.

Madrone most commonly rubs shoulders with mixed-hardwood tree species that often have some conifer overstory (without completely shading them).  A member of the Douglas-fir/tanoak forest, madrone makes up the secondary canopy, while Douglas-fir (Pseudotsuga menziesii) with tanoak (Lithocarpus densiflorus) typically create an overstory. Less commonly, madrone mingles with coast redwood (Sequoia sempervirens) along the northern California and southern Oregon coast, and with western hemlock (Tsuga heterophylla), Oregon white oak (Quercus garryana var. garryana), and Pacific ponderosa pine (Pinus ponderosa var. ponderosa) throughout much of its range. Washington’s San Juan Islands’ open woodlands support madrone with Douglas-fir and fescue (Festuca spp.), as well as other species such as lodgepole pine (Pinus contorta), Oregon white oak (Quercus garryana), and Rocky Mountain juniper (Juniperus scopulorum). In British Columbia, Pacific madrone grows alongside lodgepole pine. Other tree species associated with madrone include sugar pine, white fir, California black oak, giant chinquapin, bigleaf maple, bitter cherry and California laurel, according to the U.S. Forest Service. Small trees/large shrubs commonly associated include vine maple, black hawthorn, red-twig dogwood, willow, hazelnut, and red elderberry. Smaller shrub associates include manzanitas, Oregon grape, ceanothus, salal, oceanspray, poison-oak, gooseberry, wood rose, snowberry, huckleberry, and thimbleberry.

A. menziesii with oaks

Madrone mingles with Oregon white oak, aka Garry oak (Quercus garryana), in parts of its range.

 

Propagation
Pacific madrone are fairly easy to grow from seed. Collect fruit soon after it ripens, generally early to mid-fall. Because one berry can have up to 20 seeds, you won’t need more than one if you just want to grow a few trees.

Separate the seeds from the pulp of a ripe, red berry (if it has dried, soak it overnight to help release the seeds from the pulp). Place seeds in a small bowl of water for 15-20 minutes; discard those that float and allow those that sink to dry in a cool place out of sunlight. Dry seeds may be viable for a couple of years if stored properly in a cold, dry place. Place seeds on top of a fine seedling mix in autumn, either in a pot outdoors or in the soil where you want a tree to grow, and cover just slightly. I like to grow them in pots so I have a little more control, but I’ve had success both ways. If you choose to use pots, keep them moist but not wet, and keep them away from slugs and snails.

Madrone seeds reportedly are able to maintain dormancy for long periods (“scores of years”) in the soil, but when conditions are just right — cold but above-freezing temperatures and adequate moisture — dormancy is broken in late winter/early spring after cold stratification has weakened the seed coat. At that point pots should be moved into a somewhat warm (if possible), bright location, but with little direct sunlight—seedlings establish best in partial shade and will grow fairly slowly. Keep them moist, but not saturated. After they have developed their second or third set of true leaves they may be moved to bigger pots with fast-draining soil (I like to use a mix of sterilized potting soil and small gravel), handling them by their expendable first set of leaves, not their delicate stems. Water them when the top inch of soil is dry; I find it’s hard to overwater with fast draining soil, but do give them time to dry out slightly. Plant them out when they’re 3 to 10 inches tall, preferably in autumn, in the conditions described above. Don’t attempt to relocate them.

 

© 2017 Eileen M. Stark

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Pacific Northwest Native Plant Profile: Graceful cinquefoil (Potentilla gracilis)

Potentilla gracilis with sweat-bees
Nicknamed slender cinquefoil or western cinquefoil, Potentilla gracilis is a perennial herbaceous plant. It naturally occurs over much of western and northern North America at low to high elevations, mostly in moist to dry prairie and savanna ecosystems, but also in open forests, on rocky slopes and subalpine meadows. Growing from a woody crown, it has sharply divided, oval, deep green leaves with hairy, silver undersides and somewhat erect inflorescences with bright to pale yellow five-petaled flowers that bloom from early to late summer. In the Pacific Northwest, it naturally occurs in nearly every county in Oregon and Washington, as well as parts of southern British Columbia.

Closely related species include Potentilla glandulosa (sticky cinquefoil), with cream to pale yellow flowers, and Potentilla pulcherrima, the latter of which grows in montane regions. P. pulcherrima (common name: beautiful cinquefoil) comes from the Latin pulcherrima, which means “very beautiful” (aren’t they all?). Both occur mainly in the western U.S. and Canada. There are many other species of Potentilla, but P. gracilis and P. glandulosa are the most common west of the Cascades and are the most likely to be found for sale at nurseries.

Wildlife value
Native bees, butterflies, syrphid flies, and other beneficial insects are attracted to the flowers. Graceful cinquefoil is also a host plant for the caterpillars of butterflies such as the two-banded checkered skipper. It is not attractive to deer.

Try it at home
Graceful cinquefoil does best in moist, well-drained soil that’s rich in organic matter, in full to part sun. Since it’s not a tall plant (usually no more than about two feet tall) and only grows to about two feet wide, site it where it won’t be heavily shaded by other plants. You can also grow native cinquefoil in a container, but be sure it gets enough moisture. Associated species include Cascara and Oregon ash trees, and perennials such as checker mallow, Oregon iris, native lupines, and other moisture loving plants. Summer water is essential until it’s established, but even afterwards it will do best with supplemental water during the hot, dry part of summer.

© 2016 Eileen M. Stark

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Gifts of the Oregon White Oak (Quercus garryana) aka Garry Oak

Quercus garryana at Ridgefield NWR


Spring still seems out of reach
, so while we’re awaiting balmier days, let’s take a moment to appreciate some of nature’s subtle, yet generous gifts. We owe everything to the natural world and even modest contact with it refreshes and offers solace. While contemplating the obvious things that nature provides—food, water, clean air—it’s easy to overlook the little (and not so little) things.

Plants, the primary producers on this planet, belong to irreplaceable, intricate, ancient ecosystems, within which they support and depend on other species—both flora and fauna— to survive. I like to think of it as everlasting give and take. This post honors one of my favorite Pacific Northwest natives whose gifts are mammoth. Quercus garryana, commonly called Oregon white oak (or “Garry oak” by those in British Columbia and Washington), is a slow-growing, very long-lived, majestic, deciduous tree that, with time, grows beautifully gnarly. As a keystone species, oak trees are vibrant communities in themselves, and support more life-forms than any other trees in North America.

Wildlife hotspot
Late last fall, while strolling along a trail at Jackson Bottom Wetlands Preserve (just west of Portland), I was awestruck by the amount of life attracted to the broad canopy of just a single mature Oregon white oak: Visible and audible were multiple white-breasted nuthatches, black-capped chickadees, downy woodpeckers, and red-breasted sapsuckers, all busily going about their foraging business with such enthusiasm that all I could do was look upwards, my mouth agape. The birds weren’t seeking the tree’s highly nutritious acorns, which sustain many other birds, as well as insects, mammals, and reptiles—they were consuming a tasty assortment of insect herbivores, which oak trees are particularly adept at generating. Studies show that the genus Quercus hosts more caterpillars and other insect life than any other genus in the northern hemisphere. This proficiency is especially important during breeding season, when the vast majority of landbirds consume and feed their young highly nutritious insects or their larvae, and other arthropods such as spiders—not seeds or fruit. Other studies show a higher diversity of bird species in oak forests than in nearby conifer forests (although pine forests are quite exceptional as well).

Like other native keystone tree species, Oregon white oak peacefully regulates ecosystem processes like nutrient cycling and energy flow, which provides benefits to wildlife (and the rest of us) that seem endless. Besides the obvious shade, beauty, and exchange of oxygen and carbon dioxide that these trees offer (trees really are the best carbon sink), inconspicuous flowers—which typically bloom in late spring—provide for pollinators like native bees, while the buds of forthcoming rounded, deeply lobed leaves play host to the larvae of gray hairstreak, Lorquin’s admiral, echo blue, California sister, and propertius duskywing butterflies. Speaking of leaves, it typically retains dead leaves on its branches until spring, a process known as marcescense. (It’s believed that marcescense, which is more common on young trees, may serve to protect new buds on branches by discouraging browsing animals from grazing. There’s also speculation that marcescent leaves help oaks create a nutrient-rich mulch when the trees need it most —in springtime. But no one knows for sure.)

In addition, cover, perches, and nesting habitat go to birds such as woodpeckers and vireos, as well as native squirrels. Oaks’ acorns sustain squirrels and other mammals, as well as many bird species. Fallen leaves, which might provide habitat for arthropods, amphibians and reptiles, slowly break down into a rich leaf mold that supports soil-dwelling invertebrates and numerous fungi that allow neighboring plants to thrive. Sugars and carbon are provided for mycorrhizal fungi, which reciprocate with nutrients for growing plants and contribute to the soil carbon pool. Intact bark creates microhabitat for mosses, as well as lichens that supply food, shelter, and nesting material, while loose bark and twigs contribute to nest building as well as browse for deer, which in turn feed carnivores like cougars.

And as oaks deteriorate with advanced age (which can be 500 years), they continue to deliver. Dead trees can last many years as snags, which provide food, nesting material, and housing to cavity nesters like owls, kestrels, woodpeckers and chickadees, as well as bats who may roost in old holes or under loose bark.

How it grows
Elevation, climate, soil, and water persuade Oregon white oak to vary immensely in habit and size. While it thrives in cool, coastal areas and near the edges of streams and wetlands where it tolerates seasonal flooding, it also flourishes in droughty inland sites where it may grow both individually and in groves on low hills surrounded by grasslands. When it occurs on gravelly sites or rocky slopes with thin soils, it often has a shrub-like or scrubby habit. Along the blustery Columbia River Gorge, where it grows with little rainfall and atop hundreds of feet of layered basalt, harshly battered trees grow gnarled but hang on thanks to a very extensive and strong root system. As seedlings, this oak’s root mass may be ten times as large as the aboveground growth.

Within the richer, deeper, riparian soils amongst tapestries of dazzling wildflowers and grasses in the Georgia Basin-Puget Trough-Willamette Valley ecoregion of British Columbia, Washington and Oregon, it acts as a keystone structure, typically growing a very broad canopy, and reaching heights 100+ feet over hundreds of years. Gigantic root systems may grow two or three times wider than the canopy. The ecoregion includes savannas (grassland with trees scattered at least 100 feet apart), upland prairies (another type of grassland), wet prairies, and shady oak woodlands with a continuous or semi-open canopy. I’ll call them, collectively, prairie-oak ecosystems.

Endangered ecosystems
To really appreciate an oak, it’s helpful to know something about its unique ecosystems that once provided some of the richest habitat in the world. The historic range of Q. garryana stretches from low elevations of southwestern British Columbia (including Vancouver Island and nearby smaller islands) to California. In Washington, it occurs mainly west of the Cascades on Puget Sound islands and in the Puget Trough, and east along the Columbia River. In Oregon, it is indigenous to the Willamette, Rogue River and Umpqua Valleys, and within the Klamath Mountains.  

When pioneers and naturalists encountered prairie-oak ecosystems, they found a breathtakingly beautiful and rich mosaic of plant and animal life. Journals of early Oregonians described massive prairies with five-mile-wide dense forests of ash, alder, willow, and cottonwood that skirted meandering rivers within floodplains. Marshes and sloughs developed during high water periods but often dried out by late summer. At higher elevations within these forest corridors were oak and associated trees. Above the floodplains were upland prairies, filled with herbaceous plants and grasses that could tolerate the parched soil of summer, as well as winter wet. Oak woodlands stood on low hills above the valley floors, surrounded by grasslands, also known as savanna.

But the landscape was not untouched or pristine. Aboriginal peoples managed parts of the ecosystems following the last glacial period, frequently using prescribed burning to boost edible plant productivity, aid the hunting of wildlife, limit the growth of conifers, and facilitate travel, particularly in the northern parts of the oak’s range. Harvesting of plants such as camas (Camassia spp.) and chocolate lily (Fritillaria affinis) also caused soil disturbance, but their eco-cultural manipulations pale greatly compared to what came later.

Since Euro-American settlement, as much as 99 percent of the original prairie-oak communities that were present in parts of the Pacific Northwest have been lost and many rare species dependent on them are at risk of extinction. Extensive destruction and fragmentation began with settlement in the 1850s, with clearing, plowing, livestock grazing, wildfire suppression, and cutting of trees for firewood and manufacturing. Prairie wetlands bejeweled with wildflowers were drained and ditched. Later, subsidies to ranchers encouraged more destructive grazing, while urban sprawl and agricultural use—fueled by human population increase—intensified. Invasion of nonnative species, and the encroachment of shade tolerant and faster growing species—that proliferate with fire suppression—outcompeted oaks and decimated additional native flora and fauna. Prairie-oak ecosystems and associated systems still continue to disappear at human hands, and isolation of the tiny remaining fragments prevents the migration of wildlife and healthy genetic material from one area to another. Other detrimental factors include diseases and parasites, climate change, and the loss of wildlife that cache acorns and perform other essential functions.  

Conservation
Despite continual destruction, there is a renewed and growing appreciation for the diversity and beauty of these habitats, motivated by recognition that we are responsible for what’s been destroyed, an admiration for the interconnected wild species the habitat supports, and a reverence for an iconic, magnificent tree. Intervention has become intensive, and collaborations and partnerships—along with private landowners, who are key partners—are working to reverse the downward trend with preservation, restoration, and management tools, although “a major restoration challenge is restoring wet prairie habitat to a level at which it can maintain resistance to invasive species,” according to the Institute for Applied Ecology.

Regeneration of oak seedlings is essential, but is often difficult. Acorns look tough, but they are viable for only about a year and may be subject to parasitism, weather extremes, and genetic isolation. Consequently, just a small percentage become trees. Two independent studies determined that oak seedlings do best when caged, but protection from other deterrents—drought, competing plants, and rodents—is important, depending on location.

Regional conservation groups include the Garry Oak Ecosystems Recovery Team and the Cascadia Prairie-Oak Partnership.

Try it at home
While the maintenance of only fragments of a past ecosystem is a poor alternative to former richness, if you live in the ecoregion (or other impoverished oak-dominated ecosystem) and want to help, choose this native tree. Even a single isolated tree can be a critical habitat structure on the landscape. It’s the only oak native to Washington and western Canada, and the dominant one in Oregon (black oak—Quercus kelloggii—is another beautiful and valuable large tree that occurs from Lane County, Oregon, south to Baja, at low to high elevations).

An Oregon white oak tree needs a mostly sunny, well-drained site that can accommodate its eventual size aboveground (25-50 feet wide, depending on spacing) and enormous root systems described above. Those grown on poor, dry, rocky sites will grow quite a bit smaller and have a shrubby habit. When planting more than one, space trees 20 to 60 feet apart, using the closest spacing only in dry, rocky terrain. It may be most helpful to visit a nearby natural area and then try to mimic nature’s arrangement.

To maintain genetic integrity, always choose trees or seeds that originated from trees close to your location and from similar terrain. For best results, plant dormant saplings in late fall after rains begin. After watering, apply about three inches of an organic mulch to reduce evaporation and keep weeds (that can steal water and nutrients) down. I prefer low-nitrogen leaf compost, spread out to the tree’s drip line and kept at least a foot from the trunk to prevent rot. Oaks do not need rich soil, so don’t apply synthetic or organic fertilizer because most North American trees don’t need fertilizer and may even respond adversely to it. And don’t use those watering bags that only water at the base of the trunk and may promote rot

Though this species is drought tolerant, provide ample summer water, deeply and infrequently until established. During the first summer I like to water roughly every five days with about 10 gallons of water that’s applied so that it sinks in slowly. During the second and third summers, water once a week, 10-15 gallons, being sure to water out to the root zone (drip line) and beyond—root spread can be more than twice that of the crown. If severe heat and prolonged droughts appear to be stressing a young tree, provide more water. After the first few years it may do fine on its own, but do water it (deeply) if it appears to be drought stressed. Keep the area well weeded and don’t stake trees unless they are in very windy areas—they’ll grow much stronger if left unsupported. Keep in mind that soil compaction, hardscape, lawns and irrigation systems around water-sensitive oaks are a major cause of their decline in residential areasHere is more info on how to plant Oregon white oak.

Grab a partner
As with other native species, oaks will function best when grown within a habitat and community type that consists of plants that evolved together and need the same conditions. Figuring out which community occurs in your area requires a walk in a nearby natural area where species, as well as nature’s organization, can be learned. Some associate trees that might thrive with your oak include Oregon ash (Fraxinus latifolia) on moist sites, and madrone (Arbutus menziesii) on drier sites, and Pacific ponderosa pine (Pinus ponderosa subsp. Benthamiana). For shrubs, consider california hazelnut (Corylus cornuta var. californica), osoberry (Oemleria Aquilegia formosacerasiformis), serviceberry (Amelanchier alnifolia), snowberry (Symphoricarpos albus), oceanspray (Holodiscus discolor), red-twig dogwood (Cornus sericea), and tall Oregon grape (Mahonia aquifolium), depending on your location. Sword ferns (Polystichum munitum), orange or pink honeysuckle (Lonicera ciliosa or L. hispidula), fescues (Festuca spp.), and many wildflowers, including allium (Allium cernuum), camas (Camassia spp.), meadow checker mallow (Sidalcea campestris), western columbine (Aquilegia formosa, pictured right), and shooting star (Dodecathon spp.) associate in different parts of its range.

To find out which habitat type and plant communities would likely have grown in your area, check out this Ecoregional Assessment, or query your county’s soil and water conservation district or native plant society chapter. The following publications may also be helpful:
~ Georgia Basin: Garry Oak Ecosystems Recovery Team
~ Puget Trough: Prairie Landowner Guide for Western Washington 
~ Willamette Valley: A Landowner’s Guide for Restoring and Managing Oregon White Oak Habitats

 

© 2017 Eileen M. Stark

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