Contrary to the name ‘Douglas-fir’, Pseudotsuga menziesii is a pine tree. It also happens to be one of the tallest trees in North America, with one giant at a recorded 329 feet tall. The cones appear unique, with many bracts covering up “mice tails”, as the wind-dispersed section of the seeds are called. Pseudotsuga menziesii was the first scientific name I ever remembered. I showed a cone to one of my first botany mentors, which I found particularly strange due to its structure. I have always had a fascination with these, as their common name implies it to be a fir, its scientific name a hemlock, its foliage a spruce, yet it is considered a pine.
Pseudotsuga menziesii (Douglas-fir, Red-fir, Oregon-pine, Douglas-spruce, Coast Douglas-fir (var. ‘menziesii’) [occasionally Pseudtsuga brevifolia]
Hardiness Zones: 4-6
Height: The douglas-fir grows 12.2-24.2 meters (40-80 feet) in cultivation, but one tree was recorded at 100.2 meters (329 feet), making it North America’s second tallest tree species. Trees may have once possibly topped 122 meters (400 feet) tall.
Diameter: 3.6-6.1 meters (12-20 feet) in cultivation at maturity, occasionally spreads further with older trees
Growth Rate: moderate to fast
Age: Commonly exceeds 500 years in proper care, sometimes lasts longer than a milennium.
Root System: Roots do not lift up nearby ground.
Subspecies: ‘menziesii’, ‘glauca’ (blue foliage, ‘Anguina’, ‘Brevifolia’ (shorter needles), ‘Compact’ (more conical growth), ‘Fastigiata’ (more pyramidal growth), ‘Fretsii’ (dense, short leaves and grows as a bush), ‘Nana’ (dwarf), ‘Pendula’ (drooping branches close to the ground), ‘Revoluta’ (curly leaves), ‘Stairii’ (variegated needles)
Tolerates: In a proper growing environment, P. menziesii has very few insect or disease problems. Strong winds are of little concern to Douglas-firs.
Problems (major): Droughts are especially dangerous to younger trees as the soil must remain at least moderately moist.
Problems (minor): Scale and bark beetles can harm trees under stress. Aphids may attack young trees. Root rot can affect trees with poor drainage.
Poisonous: presumably no
Soil requirements: Sandy, loamy, and clay soils are fine. No specific pH is required.
Air Requirements: not sufficiently researched
Watering requirement:medium or wet
Sun requirement: full sun
Needles: yellowish-green in ‘menziesii’, blue (Picea pungens blue) in ‘glauca’
Cones (male): pollination runs from March to May usually
Cones (female): up to 10 centimeters (4.5 inches) (seed begin ripening until around November)
Seeds require stratification: yes
Monoecious or Dioecious: monoecious (Male and female cones grow on seperate trees.)
These can grow at an elevation of of 5500 feet (var ‘glauca’ has been reported to grow at 9500 feet). The cones have unique bracts (small trident-shaped structures) that make their unique-looking cones easily identifiable. The oldest douglas-fir is estimated to be 1300-1400 years old.
These trees are narrow and pryamidal-shaped with branches hanging to the ground. Older trees are more cylindrical and only have needles on the upper third of the tree. The douglas-fir is also the state tree of Oregon.
Especially in the Pacific northwestern region of the United States, this is one of the most valuable timber trees in North America. Douglas-firs grow well as shade trees and sometimes as ornamentals.
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.