Oregon White Oak (Garryana)

The Oregon White Oak (Garryana) is generally described as a perennial tree or shrub. This is native to the U.S. (United States) has its most active growth period in the spring and summer . The greatest bloom is usually observed in the mid spring, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The Oregon White Oak (Garryana) has a long life span relative to most other plant species and a slow growth rate. At maturity, the typical Oregon White Oak (Garryana) will reach up to 80 feet high, with a maximum height at 20 years of 25 feet.

The Oregon White Oak (Garryana) is usually not commercially available except under contract. It can be propagated by bare root, container, seed. It has a slow ability to spread through seed production and the seedlings have medium vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -33°F. has high tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Wildlife: Oregon oak is a valuable source of food and cover for wildlife. Gray squirrels, deer, and livestock eat acorns and the leaves of young shoots and sprouts.

Ethnobotanic: Native Americans used Acorns as a food staple.

Construction: In the Pacific Northwest, large trees were preferred for shipbuilding, railroad ties, and construction. Resistance to decay also contributed to its use as fence posts. The wood continues to be important to cottage furniture and cabinet industries.

General Characteristics

General: Oak Family (Fagaceae). Quercus garryana, a native deciduous tree up to 30 m tall throughout much of its range in the Pacific Northwest, has an open, rounded crown. However, in the southern part of its range, including interior California, it also is a shrub up to 5 m tall, which is treated as var. breweri (Engelm.) Jepson. The mature bark is brownish gray and shallowly fissured in a checker-like pattern. Leaves are oblong to obovate, 8-15 cm long, and deeply lobed (5-7 rounded lobes). The upper surfaces are shiny and dark green, but the lower surfaces are pale green. Like all oaks, Oregon oak is monoecious and wind-pollinated. The acorn cups are composed of thick, tubercled scales. The one-seeded nuts are 2-3 cm long, ovoid, and mature in one year. Flowering takes place from March to May. Fruits mature between August and November. Color images, line drawings, and a description can be found in Farrar (1995).

Required Growing Conditions

This species is known from California, Washington, Oregon, and British Columbia. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

Cultivation and Care

Adaptation: Oregon oak is best developed as a tree on slopes and valleys below 1500 m where annual rainfall exceeds 30 inches. The range in climate is considerable, extending from the relatively cool, moist Fraser Valley of British Columbia to the summer-dry Coast Ranges north of San Francisco and the foothills of the Sierra Nevada in California. Oregon oak takes the form of a shrub on nutrient-poor soils (e.g., serpentine) and drier sites, often forming clonal thickets. It is tolerant of freezing conditions and also has a broad tolerance of substrates, which vary from rocky, thin soils of ridges to the deep loams and clays of valley bottoms. Common associates in mixed forests include madrone, Douglas fir, tanbark oak, and yellow pines. In the coastal mountains and in the absence of fire, Douglas fir gradually replaces Oregon oak. Throughout much of its range, Oregon oak reproduces extensively by basal sprouts, which often develop after fires. Thus, Oregon Oak is often associated with local grasslands maintained by fire. In some areas seedlings develop into multi-stemmed plants, which may live up to 10 years, until a single shoot becomes dominant. Like most oaks, Oregon oak has an obligate relationship with mycorrhizal fungi, which provide additional moisture and nutrients.

Seed Preparation: Oak seeds do not store well and consequently seeds should be planted soon after maturity. Nuts are considered ripe when they separate freely from the acorn cap and fall from the tree. Care should be taken to collect local fruits, because they may be adapted to local environmental conditions. Viable nuts may be green to brown, and have unblemished walls. Nuts with discoloration or sticky exudates, and small holes caused by insect larvae, should be discarded.

Direct Seeding: Seeds may be planted at the beginning of the winter. Once the site is chosen, prepare holes that are 10 inches in diameter and 4-5 inches deep. One gram of a slow-release fertilizer should be placed in the bottom and covered by a small amount of soil. Place 6-10 acorns in each hole at a depth of 1-2 inches. Rodents or birds should use temporary enclosures to minimize herbivory. A simple enclosure can be constructed from a one-quart plastic dairy container with the bottom removed and a metal screen attached. Towards the end of the first season, seedlings should be thinned to 2 or 3 per hole and to one seedling by the second season. Supplemental watering may be necessary if a drought of 6 weeks or more occurs during the spring.

Container Planting: Seeds may be planted in one-gallon containers, using well-drained potting soil that includes slow-release fertilizer. Tapered plastic planting tubes, with a volume of 10 cubic inches, may also be used. Seeds should be planted 1-2 inches deep and the soil kept moist and aerated. Seedlings should be transplanted as soon as the first leaves open and become firm, which generally occurs in spring. Planting holes should be at least twice as wide and deep as the container. Seedlings may require watering every 2-3 weeks during the first season. Care should be taken to weed and mulch around young plants until they are 6-10 inches tall.

General Upkeep and Control

Natural regeneration through sprouting and seed germination, is promoted by fire, which contributes to expansion and persistence of Oregon oak stands. Continued disturbance by fire may result in pure stands that are often associated with an understory of grasses or scattered shrubs. Oregon oak is not as susceptible to oak crown and root rot fungi (e.g., Inonotus, Ganoderma, and Laetiporus) as other oaks, unless disturbed by changes that include irrigation. Activities that disturb or compact soil around large trees, especially in urban settings, should be avoided.

Plant Basics
Growth Rate Slow
General Type Tree, Shrub
Growth Period Spring, Summer
Growth Duration Perennial
Lifespan Long
Plant Nativity Native to U.S.
Commercial Availability Contracting Only
Physical Characteristics
Bloom Period Mid Spring
Displays Fall Colors Yes
Shape/Growth Form Single Stem
Drought Tolerance High
Shade Tolerance Intolerant
Height When Mature 80
Vegetative Spread None
Flower Color Yellow
Flower Conspicuousness No
Fruit/Seed Abundance Medium
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Slow
Gardening Characteristics
Propagations (Ways to Grow) Bare Root, Container, Seed
Moisture Requirements Low
Cold Stratification Required No
Minimum Temperature -33
Soil Depth for Roots 42
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Resprout Ability Yes
Responds to Coppicing Yes
Growth Requirements
pH Range 5–7.5 pH
Precipitation Range 10–10 inches/yr
Planting Density 300–800 indiv./acre
Soil Textures Coarse, Fine, Medium
Soil Depth for Roots 42
Minimum Frost-Free Days 75 day(s)
Salinity Tolerance None
CaCO3 Tolerance None
Sustainability & Use
Leaf Retention No
Palatability Medium
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database, plants.usda.gov.
National Plant Data Center, Baton Rouge, LA 70874-4490 USA