Many people choose the Douglas fir as their Christmas tree each year. The name is a bit misleading, as this does not belong to the fir genus (Abies). The Douglas fir is one of the tallest conifers. Oregon chose this as its state tree.
The Douglas fir is not a true fir tree. The genus name (Pseudotsuga) suggests that this is similar to hemlock trees. Pseudo- means false, and Tsuga is the genus for hemlocks. The species is menziesii.
This tree is one of many conifers included in the Pinaceae family. Others are cedars, the deciduous conifers (Glyptostrobus, Larix, Metasequoia, Pseudolarix, and Taxodium), fir trees, pine trees, and spruce trees.
Besides Douglas fir, other possible names include Doug-fir, false spruce, red fir, Oregon pine, Douglas pine, yellow fir, and Douglas spruce. Pseudotsuga menziesii var. menziesii is the coast Douglas fir. Pseudotsuga menziesii var. glauca may be called either the interior Douglas fir or the Rocky Mountain Douglas fir.
Preferred USDA Hardiness Zones
If you live in zones 4 to 6, this could be the evergreen tree for you.
Size and Shape
This tall conifer can reach heights of anywhere from 40 feet to over 300 feet tall, but there are smaller varieties available for the home landscape. As it grows, the Douglas fir forms into a pyramidal shape.
The Douglas fir must have full sun wherever you plant it.
Foliage, Flowers, and Fruit
The Douglas fir is monoecious and both male and female strobili are produced on the tree. The red-brown cones are long and have distinct bracts that come out between the scales.
The ideal soil for this tree is an acidic loam that drains. You can work on making your soil more acidic.
Don't plant this evergreen in an area where there is drought.
Maintenance and Pruning
Douglas fir is best left alone as far as pruning goes unless it needs to be trimmed for damaged, diseased, or dead branches.
Pests and Diseases
There are quite a few pests and diseases that may potentially affect your Douglas fir, but you usually shouldn't have major problems. They include:
- Black pine leaf scale (Nuculaspis californica)
- Black vine weevil (Otiorhynchus sulcatus)
- Conifer twig weevil (Pissodes spp.)
- Cooley spruce gall adelgid (Adelges cooleyi)
- Douglas-fir bark beetle (Dendroctonus pseudotsugae)
- Douglas-fir bud mite (Trisetacus pseudotsugae)
- Douglas-fir cone gall midge (Contarinia oregonensis)
- Douglas-fir cone moth (Barbara colfaxìana)
- Douglas-fir dwarf mistletoe (Arceuthobium do)
- Douglas-fir pitch moth (Synanthedon novaroensis)
- Douglas-fir seed chalcid (Megastigmus spermotrophus)
- Douglas-fir tussock moth (Orgyia pseudotsugata)
- Douglas-fir twig weevil (Cylindrocopturus furnissi)
- Elongate hemlock scale (Fiorinia externa)
- Fall webworm (Hyphantria cunea)
- Fir coneworm (Dioryctria abietìvorella)
- Giant conifer aphid (Cinara spp.)
- Monterey pine aphid (Essigella californica)
- Pine needle scale (Chionaspis pinifoliae)
- Silver-spotted tiger moth (Halsidota argentata)
- Spruce aphid (Elatobium abietina)
- Spruce gall adelgid (Adelges abietis and Adelges cooleyi)
- Spruce spider mite (Oligonychus ununguis)
- Western pine spittlebug (Aphrophora fulva)
- Western spruce budworm (Choristoneura fumiferana)
- Heart rot fungi
- Laminated root rot (Phellinus weirii)
- Needlecast (Rhabdocline pseudotsugae)
- Red ring rot (Phellinus pini)
- Shoestring root rot (Armillaria mellea)