Douglas fir
Pseudotsuga menziesii
also called fir, doug fir
Keeps its shape only while the central leader is left alone, and it needs more moisture than a pine would.
- Type
- Tree · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Sunlight
- Full sun to partial shade, with open, airy positions best of all.
- Watering
- Keep the soil consistently moist — it is less drought-tolerant than a pine.
- Feeding
- Feed in spring only on poor soil; established trees rarely want it.
- Frost tolerant
- Yes
- Pruning
- Prune as little as possible, and never touch the central leader.
- Overwintering
- Extremely cold-hardy — nothing needs doing for winter.
- Apr–May Bud Break
- May–Oct Spring Growth
- Oct–Dec Growing
- Jan–Apr Growing
- Plant spacing
- 16 ft 5 in
- In-row spacing
- 16 ft 5 in
- Between rows
- 20 ft 6 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, shallow and far-reaching
- Working depth
- 12–24 in
- Can reach
- 4 ft down where the soil allows
- Spread
- 33–49 ft across, about 2–3× the width of the plant
Almost all of a tree’s roots are in the top two feet of soil, where the air is, and they run out well past the branch tips. The deep taproot most people picture belongs to the seedling; the tree grows out of it and spends the rest of its life spreading sideways instead.
The habit is Douglas fir’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Adelgids & woolly aphids Adelgid (a woolly aphid-like pest) — white waxy tufts on needles and young shoots
- Bark beetles Bark beetle working under the bark of stressed or dying trees
- Honey fungus Honey fungus on trees that are stressed or badly drained
- Phytophthora root and foot rot Phytophthora root rot where soils stay waterlogged
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Garden birds PasseriformesHunts Bark beetles
Both things are true: birds strip your currants and a brood of blue tits takes several thousand caterpillars out of one fruit tree in a fortnight. Net what you must and welcome them everywhere else — a nest box near the apples is worth more than a spray.
- Green lacewing Chrysoperla carneaHunts Adelgids & woolly aphids
Its bristly larvae — "aphid lions" — impale aphids, mealybugs, thrips, and mite colonies, eating hundreds a week. Adults feed on nectar and pollen from small open flowers and overwinter in hollow stems left standing.
- Ladybird (lady beetle) CoccinellidaeHunts Adelgids & woolly aphids
The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working.
Trees, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com