Douglas Fir

two douglas fir trees
Douglas Fir Trees - Photo by Bill Cook, Michigan State University, Bugwood.org

The Douglas fir is native to the western mountain states. It has been planted widely in Iowa for ornamental and windbreak use.

Hardiness: Zones 5 through 6

Growth Rate: Moderate

Mature Shape: Pyramidal mature shape

Height: 40-60 feet

Width: 15-25 feet 

Flowering Dates: March - June

Seed Dispersal Dates: September - March

Seed Bearing Age: 7-10 years

Seed Bearing Frequency: Every 2-11 years

Seed Stratification: Prechill 21 days at 34°F to 40°F

The tree has dense and compact foliage, holds its branches well to the ground. It grows 40 to 60 feet high. The needles are soft, flattened, slightly pointed, 1 to 1-1/2 inches long and grow around the branch to give it a full, rounded appearance. They are grooved on the upper surface, and have a white band on each side of a prominent midrib beneath. 

The twigs are fine and the buds are long, pointed, dark orange-red in color and shiny.  They are sometimes termed "cigar-shaped."
  
The cones of the Douglas fir are distinct, 1-1/2 to 4 inches long.  Protruding from beneath the thin rounded scales is a conspicuous, three-pointed bract.

On older trees the reddish brown bark is broken into oblong, longitudinal plates and may be 10 to 12 inches thick.  On young and smaller trees, the bark is thin, ashy gray and may have resin blisters.

douglas fir twig with needles
Douglas Fir Twig - Photo by Paul Wray, Iowa State University 

brown douglas fir cone
Douglas Fir Fruit - Photo by Paul Wray, Iowa State University

young green douglas fir fruit or cone
Young Douglas Fir Fruit - Photo by Paul Wray, Iowa State University