Abies concolor, the white fir, concolor fir, or Colorado fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Sierra Nevada and southern Rocky Mountains, and into the isolated mountain ranges of southern Arizona, New Mexico, and Northern Mexico and may occasionally reach 350 years of age.
It can be found from 6000 ft. to 11,000 ft. in elevation in the Rocky Mountains in Colorado and New Mexico to the Coast Range in California and Oregon. Near the Pacific Coast it can occur as low as 2300 ft. elevation. In the average home landscape the tree will reach 30-50 feet tall and 15-25 feet wide when mature.
White fir was first collected by Augustus Fendler on his expedition to the Santa Fe area of New Mexico in 1846–1847. Fendler’s patron George Engelmann, a St. Louis area physician and botanist, then described the plant. This tree was first collected in California by William Lobb on his expedition to California of 1849–1853, after it was overlooked by David Douglas in his 1825–1827 expedition to the Pacific coast region.
The tree grows in an almost perfect pyramidal Christmas tree shape when young (and it is grown commercially as a Christmas tree), with horizontally tiered branches. At maturity the tree develops a dome-like crown. The short, flat, soft needles are silvery blue-green both above and below, although the undersides may have a whitish bloom. The needles have a slight citrus smell when broken. The smooth gray bark develops attractive deep, irregular furrows and irregular, flattened scales on mature trees. The oblong cones are held upright, and vary in color from yellow-green to purple. They mature in one season and generally disintegrate after the seeds are shed, falling off the tree in September and October.
Best grown in rich, medium moisture, slightly acidic, sandy/gravelly, well-drained soils in full sun to part shade. Best in full sun. Established trees tolerate some soil dryness, but best performance usually comes with moist soils. Trees generally grow poorly in heavy clay soils. This tree thrives in areas with long winters followed by cool summer climates, and it usually does not grow well in the heat and humidity south of USDA Zone 7. It is, however, considered to be the best of the firs for tolerating the growing conditions of the Midwest.
White fir is a general, all-purpose, construction-grade wood used extensively for solid construction framing and plywood. A significant portion of the Christmas trees used in California are young white fir. These trees are harvested from natural stands, from regeneration areas where the trees are cultured for as long as 11 years before harvest, and from areas used specifically for Christmas tree production.
Characteristics
- Appearance: Douglas fir can grow to impressive heights, often reaching 70-90 meters (230-295 feet) in ideal conditions. The bark is thick, corky, and deeply furrowed, especially on older trees. The leaves are flat, needle-like, and green to blue-green, arranged spirally on the branches.
- Cones: The tree produces distinctive, pendent cones that are 5-10 cm (2-4 inches) long, with bracts that protrude between the scales, giving them a unique three-pronged appearance.
- Wood: Douglas fir wood is highly valued for its strength and durability. It is used in construction, including for beams, plywood, and flooring, as well as for paper and pulp products.
- Growth Rate: The tree is known for its rapid growth, making it a popular choice for timber plantations. It can grow 24-60 cm (10-24 inches) per year under favorable conditions.
- Longevity: Douglas firs are long-lived trees, with some specimens living for several hundred years. They are capable of living over 1,000 years in their native habitats.
Cultivation
- Soil: Douglas fir prefers well-drained, loamy soils but can adapt to a range of soil types, including sandy and clay soils. It thrives best in slightly acidic to neutral soils.
- Light: This tree species prefers full sun to partial shade. It requires adequate sunlight for optimal growth, especially in its early stages.
- Watering: Regular watering is important, especially during the first few years of growth. Mature trees are more drought-tolerant but still benefit from occasional deep watering during dry periods.
- Climate: Douglas fir grows well in temperate climates with moderate rainfall. It is hardy in USDA zones 4-6, with some varieties tolerating even colder conditions.
- Planting: Plant Douglas fir in a location where it has ample space to grow. It is commonly used in reforestation, windbreaks, and as an ornamental tree in large landscapes.
- Maintenance: Minimal pruning is required, primarily to remove dead or damaged branches. It is generally resistant to pests and diseases, although it can be susceptible to root rot and certain insect infestations.