Doug Fir Pseudotsuga menziesii

Douglas-fir is a large conifer, evergreen tree in the Pinaceae (pine) family that grows 40 to 80 feet tall when cultivated but as tall as 300 feet in the wild. It is one of the largest trees in the world, and one of the most important timber species in the United States. Young trees have a narrow and spired pyramidal shape with lower branches drooping and upper branches ascending. As the tree matures, it becomes cylindrical, loses its lower branches and resulting in branching only at the top third of the tree. This tree has unique forked cone bracts that is distinctly different from many other conifers. The cones are about 3 to 4 inches long and pendulous. The needles are flat, spirally arranged, dark green and up to 1.25 inches long with white banding on the undersides. They are fragrant when bruised or crushed. 

It is native to Southwestern British Columbia to West Central California. The Douglas-fir is the State tree of Oregon. It grows best in northern or northwestern climates of the United States. The species is found in coastal areas in elevations up to 5500 feet, foothills, lower mountains, cool mesas, and in some subalpine areas.. It is intolerant to the heat and high humidity of the Piedmont and Coastal Plains of North Carolina. The trees are grown with success in the mountains of North Carolina and sold as Christmas trees.

The genus name, Pseudotsuga, is compounded from two words: the Greek word pseudo, meaning false or untrue, and the Japanese tsuga, meaning hemlock which references to the fact that it is often confused with hemlock trees. The epithet, menziesii, is in honor of Archibald Menzies, a naval surgeon and botanist from Scotland. The common name, Douglas Fir, honors David Douglas who was a Scottish botanist. He introduced this tree and many other plants to Great Britain for cultivation.

Plant it in full sun, acidic to neutral, moist, well-drained, organically rich soil.  Keep it well watered since it is intolerant to drought. It is easy to transplant when it is small. The Douglas-fir is intolerant to heat, humidity, and warm temperatures at night.

There are two distinctly different geographic varieties of the Douglas-fir. Coast Douglas-fir (Pseudotsuga menziesii var. menziesii) is a large tree with dark yellow-green needles and large cones that is found on the Pacific coast. The Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) is a medium-sized tree with shorter bluish-green needles and small cones. Dwarf cultivars are available commercially.

The Douglas-fir is a valuable timber producer and forest tree. This large tree provides winter interest with its attractive needles but is best left to natural woodland habitats. Growing to a towering height of 40 to 300 feet tall, it is not suitable for most home landscapes.

Seasons of Interest:

Foliage: Year-round             Fruits:  Late Summer

Quick ID Hints:

• large conifer, evergreen, pyramidal when young, columnar with age and loses lower branches
• bark on young twigs is smooth and gray, older bark reddish-brown, thick, and develops ridges and deep furrows
• stems are straight, slender, reddish-brown with the long pointed, reddish-brown buds
• needles are fragrant, flat, spirally arranged, up to 1.25 inches long, dark green to yellow-green or bluish-green with 2 wide stomatal bands on the undersides
• male flowers are oblong, red to yellow and the female is reddish with long bracts.
• cones are woody to semi-woody, light brown when mature, 3 to 4 inches long with rounded scales, 3-lobed bracts with small appendages on each bract that resembles 3 pointed tongues

Insects, Diseases, and Other Plant Problems: Weevils, bark beetles, spider mites, aphids, galls, and Douglas-fir beetle are potential insect pests. Shoestring rot, root rot, Heart rot, and needle cast are occasional disease problems.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.