Siberian larch

How to recognise it

Habit

Large conifer of 20–40 m, with a straight trunk and a narrowly conical crown that becomes broader and more open with age. In Belgium it usually stays smaller.

Needles

Soft, 2–4.5 cm, light to fresh green; in tufts of 20–50 on short side shoots, single and spirally arranged on new long shoots. Golden yellow in autumn, after which they fall.

Flowering

In March–April, as the needles open: yellow male cones under the shoots and upright, pink to red female cones.

Cones

Egg-shaped, 2.5–4 cm, upright on the branches. The scales are densely and softly hairy on the outside and have a smooth, slightly incurved edge. Ripe in the first autumn, but they stay on the tree for years.

Twigs and bark

Young twigs pale yellow to straw-coloured; the bark of older trees is thick, red-brown to grey-brown and deeply furrowed.

Look-alikes

European larch has cones with smooth or only slightly hairy scales. Japanese larch has blue-green needles, red-brown twigs and cones whose scales curl outwards at the tip, like a little rose. Certainty is not always possible: larches also hybridise with each other.

Flowering: March–April · Pruning: December–January

Why grow it?

• A conifer with seasons: fresh green in spring, golden yellow in autumn and bare in winter.
• The light crown lets plenty of light through, so a rich layer of plants can grow beneath the tree.
• The seeds in the cones are food for siskins, redpolls and crossbills.
• Extremely hardy: one of the most cold-tolerant trees in the world.
• An interesting tree for a collection, to compare with European and Japanese larch.

Siberian larch: where does it grow best?

• In the wild in the taiga of north-eastern European Russia and western Siberia, as far as the Altai and Mongolia: open forest, riverbanks and slopes, in a continental climate with long, severe winters and short, warm summers.
• In the garden: full sun; larches do not tolerate shade.
• Well-drained, not too fertile soil, from sand to loam; not wet soil.
• Choose an open spot that warms up late in spring, such as a north-facing slope, but not a frost pocket where late frosts linger.
• Allow 8–10 m of space: this is a tree for a large garden, a park or a woodland edge.

Goes well with

• Silver birch: Another light-loving pioneer of northern forests; its white trunks look lovely with the golden autumn colour.
• Scots pine: An evergreen neighbour from the same northern forests that makes up for the larch’s bare winter look.
• Rowan: A small tree with berries for birds that does well beside the light larch crown.
• Bilberry: Low underplanting for acid, sandy soil under the light crown, with berries for birds.

Siberian larch: when and how to plant it?

1. Buy a young tree of 60–120 cm, bare-root or in a container, from a forestry nursery.
2. Plant bare-root stock in November–December, or later in winter in mild weather, while the tree is bare: it comes into leaf very early in spring.
3. Dig a planting hole twice as wide as the roots, loosen the bottom and set the tree at the same depth as before.
4. Firm the soil well, water straight away with 10–20 litres and mulch around the base.
5. Put in a short, angled stake on the windward side; larches grow fast in their first years.
6. Never dig up young trees in woodland: buy them from a nursery.

Care

Watering

For the first two summers, a good can of water every week in dry spells. After that it manages on its own.

Feeding

Not needed. Leave the needle litter under the tree.

Light

Give it space all round and do not plant it under or right next to other trees: in shade its branches die off.

Late frost

If a young tree comes into leaf early after a mild winter, cover it with fleece on frosty nights.

Underplanting

Woodland plants and grasses grow well under the light crown; there is nothing you need to do.

Tip: For an ordinary Belgian garden or woodland edge, choose European or hybrid larch instead: they grow much better in our mild climate. Siberian larch is mainly one for a collection, in an open spot that warms up late in spring.

Pruning and mowing

Pruning months: December–January.

When: Rarely needed. Prune in December–January, when the tree is bare and not yet in leaf.

How:

• Remove dead, broken and diseased branches, especially those with cankers.
• Keep a single leader: if there are two, cut out the weaker one.
• You can gradually remove the lowest branches, a few each year, flush with the trunk.

Caution: Do not prune in spring: in Belgium Siberian larch comes into leaf as early as February–March, and the wounds then bleed resin. Never cut off the leader.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Pick the cones in autumn and let them open in a warm place. Keep the seeds cold and moist in the fridge for a few weeks and sow them outdoors in a tray or seedbed in March–April. Many seeds are empty: sow generously.

Grafting

Special trees are grafted onto a rootstock of another larch; that is a job for a nursery.

Siberian larch: how does it get through the winter?

Hardy to −45 °C.

• Deciduous: the needles turn golden yellow in October and fall; the tree stays bare all winter, with the cones still on the branches.
• One of the hardiest trees in the world: frost is never a problem for it.
• Its weak point in Belgium is the mild winter: during a warm spell in February or March it comes into leaf, and a night frost afterwards damages the young needles.
• In winter, siskins and crossbills pick the seeds out of the cones.

Diseases and pests

• Frosted shoots: Brown, limp young needles and shoots after a late frost. The tree usually regrows; avoid planting in a frost pocket in future.
• Larch canker: Sunken, resin-weeping wounds on trunk and branches, caused by the fungus Lachnellula willkommii. Cut out affected branches and plant in an open, airy spot; trees weakened by a mild, damp climate are more susceptible.
• Larch casebearer: Tiny caterpillars of a casebearer moth hollow out the needles in spring, so the tree looks brown. It usually recovers on its own; tits eat the caterpillars.
• Larch adelgid: White, woolly tufts on needles and shoots. Usually harmless; hose young trees down with a strong jet of water.

Through the year

• January: Prune if needed. Plant bare-root stock in mild weather.
• February: In mild weather it may already come into leaf. Cover young trees with fleece on frosty nights.
• March: Needles open and flowering: yellow male and pink female cones.
• April: Flowering. Sow seed in a tray.
• May: Fresh green needles. Cut off frosted shoots.
• July: Water young trees in dry spells.
• September: The cones ripen. Pick cones for seed.
• October: Golden yellow autumn colour.
• November: Needles fall. Plant bare-root stock.
• December: Prune if needed. Siskins and crossbills in the cones.

Did you know?

• Larches are the only conifers in our region that drop all their needles in autumn. That way they lose no water through their needles during the long, frozen winter.
• In Russia, larch forests cover an enormous area: larches are among the most widespread trees there.
• Larch timber from Russia is often sold in Belgium as ‘Siberian larch’ for cladding and decking: it is heavy, resinous and naturally fairly durable.