Siberian fir

How to recognise it

Habit

Narrow, spire-like cone with short, thin branches; up to 30 m in the wild, rarely more than 10–15 m in Belgium.

Needles

Soft and flexible, 2–4 cm long, narrow, with a blunt or slightly notched tip; fresh green with two whitish bands underneath. When crushed they smell fresh and resinous.

Flowering

In April–May: small male cones under the shoots and small upright female cones at the top of the crown.

Cones

Upright, cylindrical, 5–9 cm, bluish to purple when young, brown when ripe, with hidden bracts. They break up on the tree in autumn.

Bark

Smooth and grey with many resin blisters; it stays smooth for a long time, even on older trees.

Look-alikes

Balsam fir from North America looks very similar: also a narrow crown, resin blisters and small cones. Without a label they are hard to tell apart. European silver fir is broader, with stiffer needles and larger cones.

Flowering: April–May · Pruning: February–March

Why grow it?

• One of the hardiest trees in the world: frosts of −40 °C and below do not harm it.
• Narrow, spire-like shape: for a fir it takes up little room.
• Soft, fragrant needles that do not prick.
• Evergreen shelter for birds such as goldcrests and tits.
• A fascinating collector’s tree: a piece of Siberian taiga in a park or large garden.
• Seeds from the disintegrating cones feed squirrels and seed-eating birds.

Siberian fir: where does it grow best?

• In the wild in the cold taiga and in mountain forests, on moist, cool soil, often in valleys and along rivers, with long, harsh winters and short summers.
• In the garden: sun to partial shade, in a cool spot; not against a warm south-facing wall.
• Moisture-retentive, humus-rich and preferably slightly acid soil; it cannot stand drought or heat.
• Choose a spot that warms up late in spring, such as a north-facing slope, but not a frost pocket where cold air lingers.
• It stays narrow: allow 4–5 m width.

Goes well with

• Silver birch: Grows with the fir in the taiga; its white trunks and light foliage add contrast.
• Rowan: A small tree of cool forests, with flowers for insects and berries for birds.
• Bilberry: A low shrub for acid, moist soil at the edge of the crown, with berries for people and birds.
• Scots pine: Another conifer of the taiga, completing the light, open look of a northern forest.

Siberian fir: when and how to plant it?

1. Buy a young tree in a container or rootballed from a tree nursery; it is not available everywhere, so ask a specialist grower of collector’s trees.
2. Plant in October–November or in March, before it comes into growth.
3. Dig a generous hole and mix in leaf mould; set the tree at the same depth as it was in the pot.
4. Firm the soil well, water generously straight away and mulch with leaf mould or needle litter.
5. Stake a larger tree for the first few years with an angled stake on the windward side.
6. Never dig up young trees in the wild: buy them from a nursery.

Care

Watering

It likes cool, moist roots: water generously and regularly in dry summers, even after the first years.

Mulching

A thick layer of leaf mould or needle litter keeps the roots cool and moist.

Feeding

Not needed. Leave its own needle litter in place.

Late frost

Cover young trees with fleece if a night frost is forecast after bud break.

Leader

Always keep the straight leading shoot. If it forms two leaders, cut out the weaker one.

Tip: Plant it in the coolest spot in your garden and keep the soil moist with a thick mulch: the later it comes into growth in spring and the less it dries out, the healthier it stays.

Pruning and mowing

Pruning months: February–March.

When: Rarely needed. Do small corrections in February–March, before bud break.

How:

• Cut out dead, broken and frost-killed twigs back to healthy wood.
• Keep a single leader: cut out a second, competing top.
• Leave the lower branches as long as possible; only remove them once they are completely bare and dead.

Caution: Firs do not regrow from bare wood: never cut into the top or prune the tree into shape.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Pick the cones in September before they break up. Keep the seed cold and moist for 4–6 weeks and sow in a tray in March–April; keep the seedlings in light shade for the first years.

Grafting

Rarely grafted; for the amateur, sowing is the usual way.

Siberian fir: how does it get through the winter?

Hardy to −40 °C.

• Extremely hardy: in its homeland it survives winters of −40 °C and below.
• The danger lies in mild winters: after a warm spell it comes into growth too early, and a night frost then turns the young shoots brown.
• Evergreen: the narrow crown offers shelter to small birds.
• Thanks to its spire-like shape, snow slides easily off the branches.

Diseases and pests

• Late frost: In Belgium it often comes into growth very early in spring. A night frost then turns the young shoots brown and kills them. Choose a cool spot and cover young trees with fleece.
• Drought and heat: Brown needles and weak growth in dry summers. Water, mulch, and do not plant it in a hot spot.
• Woolly adelgids: White, woolly tufts on needles and shoots. Usually harmless; hose young trees down with a strong jet of water.
• Short life: In our climate it often lives less long and looks less fine than in its homeland. For a reliable fir, choose a species better suited to our climate.

Through the year

• February: Prune if needed. Have fleece ready for bud break.
• March: Plant. The buds are swelling: watch out for night frost.
• April: Bud break and start of flowering. Cover young trees on frosty nights.
• May: Flowering. Cut off frosted shoots.
• June: Water in dry spells.
• July: Water and top up the mulch in dry summers.
• August: The cones are full-sized.
• September: Pick cones for seed.
• October: Plant. The cones break up on the tree.
• November: Plant. Mulch.

Did you know?

• Sibirica means ‘from Siberia’, but its natural range reaches west into European Russia, west of the Urals.
• If you find a whole cone under a fir, a squirrel has usually bitten it off the branch: otherwise firs let their cones fall apart on the tree.
• In Russia a fragrant essential oil is distilled from the needles and twigs and used in soap and perfume.