How to Grow Douglas Fir
Pseudotsuga menziesii
Douglas fir is a fast-growing evergreen conifer from western North America, with soft, flat needles that smell of citrus when crushed and hanging cones with three-pointed bracts. It becomes a very big tree and can pass 20 m within a few decades, so plant it only where it has room as a specimen or in a shelter belt. Give it full sun or light shade and deep, moist but well-drained, acid to neutral soil; it dislikes chalk, shallow soil, waterlogging and very windy sites. Water young trees in dry spells for the first few years. It needs almost no pruning, and the central leader should never be cut.
In your Leaftide garden 
- Height
- 2500 cm
- Spread
- 800 cm
- Light
- Full sun to part shade
- Water
- Moderate
- Feed
- Feed only on poor soils in spring
- Prune
- Minimal pruning only
Yearly Lifecycle
Care Essentials
Established Douglas firs rarely need feeding. On poor or sandy soils, apply a slow-release balanced fertiliser in early spring for the first few years. Avoid feeding in late summer or autumn, which pushes soft growth that frost can damage. Yellowing on chalky soil is lime-induced chlorosis, not hunger, and feeding will not fix it.
Watch For
- Cooley adelgid (Adelges cooleyi): white woolly tufts on new needles in spring
- Swiss needle cast: older needles yellow and drop, tiny black dots under the needles
- Honey fungus on poorly drained or stressed trees
- Phytophthora root rot in waterlogged soils
Care Requirements
Light
Full sun to light shade; open but sheltered sites are best.
Douglas fir grows fastest and densest in full sun. Young trees tolerate light shade. Shelter from the strongest winds helps, because trees on shallow or wet soil can be blown over.
Watering
Moist but well-drained soil; water young trees in dry spells.
Water deeply in dry spells for the first two to three years after planting. Established trees on deep soil cope with summer dry spells, but suffer on shallow, sandy or chalky sites in long droughts.
Fertilizing
Feed only on poor soils in spring; established trees rarely need it.
On poor or sandy soils, apply a slow-release balanced fertiliser in early spring. Avoid feeding in late summer or autumn, which encourages soft growth that frost can damage.
Pruning
Minimal pruning only; never cut the central leader.
Remove dead, damaged or crossing branches in late winter. Douglas fir does not regrow from bare wood, so never cut back beyond the green needles. On mature trees the lowest branches can be removed gradually to raise the crown.
Overwintering
Fully hardy; no winter protection needed.
Douglas fir is hardy throughout the UK and most of Europe. Late spring frosts can scorch the new shoots of young trees in frost pockets, but they recover; avoid planting in hollows where cold air collects.
Growing Tips
Never cut the central leader
The central leader is the single upright shoot at the top of the tree. Removing it permanently spoils the natural conical shape, and the tree will not regrow from bare wood to hide the damage.
Mulch young trees every spring
Keep a ring of composted bark or wood chip around the base of young trees each spring. Douglas fir establishes best in evenly moist soil, and mulch holds that moisture through dry spells.
Give it deep, acid to neutral soil
Douglas fir does poorly on chalk and shallow soil, where the needles yellow (lime-induced chlorosis) and the tree is more easily blown over. Deep, moist, well-drained loam or sandy loam suits it best.
How to tell it from a true fir
Douglas fir has pointed brown buds and hanging cones with three-pointed bracts sticking out between the scales. True firs (Abies) have rounded, often resinous buds and upright cones that break up on the branch.
Pests & Diseases
Pest Cooley Adelgid
Identification: White woolly tufts on the undersides of new needles in spring; affected needles yellow, mottle and kink, and heavy attacks make young trees look thin and scorched.
- Spray horticultural oil or insecticidal soap in early spring, as the overwintering adelgids start feeding.
- Do not plant Douglas fir right next to spruces (Sitka, Engelmann, Colorado blue): the adelgid needs spruce to form its galls and complete its full cycle.
- Established trees shrug off light attacks; water and mulch stressed young trees rather than spraying.
- Systemic acetamiprid-based insecticide for young or valuable trees, following the label.
Pest Bark Beetle
Identification: Small exit holes (1–3 mm) in the bark; resin bleeding at entry points; galleries under loosened bark; dieback in the crown.
- Remove and destroy badly affected branches, or the whole tree if it is dying.
- Keep trees vigorous with watering and mulch in dry spells; healthy trees fight off most attacks.
- No effective chemical treatment once beetles are under the bark; keeping the tree healthy is the only reliable defence.
Disease Swiss Needle Cast Nothophaeocryptopus gaeumannii
Symptoms: Older needles turn yellow-brown and drop early, leaving only the youngest needles and a thin, yellowish crown; rows of tiny black dots (fruiting bodies) on the undersides of the needles, either side of the midrib.
Treatment: No fungicide is practical for garden trees. Keep the tree vigorous with mulch and watering in drought, and clear fallen needles from under small trees.
Prevention: Plant in an open, airy spot with good drainage and do not crowd trees together. In mild, damp areas expect some needle loss.
Disease Honey Fungus Armillaria mellea
Symptoms: White fungal sheets under the bark at the base; black bootlace-like strands in the soil; honey-coloured toadstools at the base in autumn; crown dieback that gets worse over time.
Treatment: No cure once established. Remove the infected tree with as much of the root system as possible, and do not replant susceptible species in the same spot.
Prevention: Avoid poorly drained or compacted soil, keep trees vigorous, and remove old stumps, which act as infection reservoirs.
Disease Phytophthora Root Rot Phytophthora cinnamomi / P. cambivora
Symptoms: Needles yellow and brown from the base of the crown upward; resin bleeding at the root collar; roots brown and rotten instead of white and firm.
Treatment: No chemical cure is available to gardeners. Improve drainage straight away and remove badly affected trees.
Prevention: Plant only in well-drained soil, avoid waterlogging, and keep mulch away from the trunk.