Downy birch

Downy birch: how do you recognise it?

Habit

Tree of 10–20 m with a light crown about 7 m wide; the twigs angle upwards and don’t hang down as in silver birch.

Twigs

Finely hairy when young, without the white warts of silver birch.

Leaves

Alternate, oval, 3–5 cm, with a shorter tip than in silver birch; singly or irregularly toothed, hairy underneath (when young).

Bark

White to greyish-white, without the black, deeply fissured diamonds at the base.

Flowers

Catkins in April–May, with the leaves: long, hanging male catkins and smaller female ones.

Fruit

Catkins that break up into winged nutlets.

Difference from silver birch

Silver birch has hanging, hairless twigs with warts, a diamond-shaped leaf and black, deeply fissured diamonds at the base of the trunk.

Flowering: April–May · Harvest and fruit: March–May · Pruning: July–October

Identify by feature: Winged seeds · White trunk

Looks like it, but isn’t

• Silver birch Betula pendula: hanging, hairless twigs with warts and a diamond-shaped leaf. Difference from silver birch

Why grow it?

• A native tree for wet, acid soil, where many other trees struggle.
• White trunks and a light crown: graceful in every season, winter included.
• Grows fast: within a few years you have a proper tree.
• Good for wildlife: many insects live on birches, and siskins and redpolls eat the seeds in winter.
• Little work: it needs hardly any pruning.

Downy birch: where does it grow best?

• Full sun: as a true light-demanding tree it cannot stand the shade of other trees.
• Acid, moist to wet soil such as peat, wet sand or a ditch bank; it copes with waterlogging better than silver birch.
• Its roots are shallow and dense: right under the crown a border or lawn will struggle.
• Allow for 10–20 m in height and a crown of about 7 m: suitable for a medium to large garden, a wet corner or a copse.

Light

Full sun

Legal basis

Acid soil

Moisture

Moist to wet

Size

20 m tall, 7 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Alder: Another native tree of wet ground: together a small wet woodland along a ditch or pond.
• Bog-myrtle: A low, aromatic shrub of wet, acid heath, lovely at the edge of a group of birches.
• Cross-leaved heath: Flowers pink in summer on wet, acid soil, in the sun at the edge of the birches.
• Alder buckthorn: A native shrub for wet, acid soil, with flowers for bees and berries for birds; food plant of the brimstone butterfly.

Good and bad companions

Goes well with

• Tolerate the shade under this tree: oregon grape, rhododendron, oleaster, japanese skimmia, garden privet, camellia, laurustinus, box-leaved honeysuckle

Downy birch: when and how to plant it?

1. Plant from November to March when the ground isn’t frozen; container plants can go in later, but not during a dry spell.
2. Choose a young plant (forestry transplant or small tree): birches establish far better young than as large trees.
3. Never let the fine roots of bare-root plants dry out: keep them in a bucket of water until planting.
4. Don’t add lime to the planting hole: it wants acid soil.
5. Water after planting and during dry spells in the first year.

Care

Watering

In dry spells during the first year; after that only in very dry summers, in a spot that isn’t naturally wet.

Feeding

Not needed: it grows on poor soil.

Self-sown seedlings

It seeds itself freely, even in gutters and borders: pull up unwanted seedlings while they are small.

Fallen leaves

Leave the fallen leaves under the tree: they break down quickly and feed the soil life.

Tip: Want a birch on wet ground? Choose the downy birch rather than the silver birch: it copes better with wet feet. Plant three young birches close together for a lovely cluster of white trunks.

Downy birch: when to prune it?

Pruning months: July–October.

When: In summer or early autumn.

How:

• Needs little pruning: only remove dead or awkward branches.
• Cut a branch just outside the branch collar, without leaving a stub; take large branches off in two stages so the bark doesn’t tear.
• Never top a birch: the crown becomes ugly and the tree goes into decline.

Caution: Don’t prune from late winter until the leaves open: the wounds then lose a lot of sap.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

Pick ripe catkins in August–September and scatter the seeds in spring on a tray of moist, acid compost. Don’t cover them: they need light to germinate.

Self-sown seedlings

You often find seedlings around a downy birch; dig them up while young, with as much root as possible, and move them in winter.

Downy birch: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy: the downy birch grows far into the far north.
• In winter the white trunks and the witches’ brooms in the bare crown stand out best.

Diseases and pests

• Witches’ brooms: Dense nests of fine twigs in the crown, caused by a fungus. Very common and harmless on downy birch; cut them out in summer if they bother you.
• Birch rust: Small orange pustules on the leaves in late summer, after which the leaves drop early. Harmless to a healthy tree; it is mainly young trees that suffer.
• Birch polypore: A white, rounded bracket fungus on the trunk of weakened or dead birches; the wood is then rotting. Have an affected tree near a path or house checked.
• Aphids: Aphids produce sticky honeydew that drips onto cars and patios. Birds and ladybirds usually deal with them.

Through the year

• March: Last month for planting bare-root trees; the sap is rising: don’t prune.
• April: The catkins flower and the leaves open; the pollen causes hay fever.
• July: Pruning season starts: remove dead and awkward branches.
• August: Pick ripe catkins for seed; pruning is possible.
• September: Pruning still possible; watch for birch rust on the leaves.
• October: Last month for pruning; the leaves turn yellow.
• November: Planting season starts.
• December: Plant in mild weather; the witches’ brooms are easy to see in the bare crown.

What can you use it for?

Also used for

As for silver birch: sap, bark for lighting fires, and firewood.

For wildlife

Characteristic of wet heath and bogs.

Caution: This pollen causes hay fever too.

Edible and useful

Sap (March–April)

The sap rises from early March to mid-April, in the weeks before the leaves break. It is clear, faintly sweet and refreshing: drink it fresh, ferment it or, with a lot of patience, boil it down to syrup (allow about 100 litres of sap for 1 litre of syrup).

Leaves (April–May)

Young leaves in April and May, while they are still slightly sticky and fragrant: for tea, or finely shredded in a salad.

Storing

Fresh birch sap spoils quickly: refrigerate it at once and drink it within 2 to 3 days, or freeze it in portions. Dried leaves keep for a year in a closed jar.

Fermenting

Birch kvass, sap fermented for a few days with a little sugar and a few raisins, is an old spring drink in Eastern Europe.

Caution: Only tap your own tree, or one you have explicit permission for, never in woods or parks. Choose a healthy tree with a trunk at least 25 cm across, drill a single small hole and tap for no longer than 1 to 2 weeks. Then close the hole with a wooden peg or grafting wax so that no more sap runs out and no disease gets in. Only drink sap that is clear and smells fresh. Pick leaves well away from busy roads and sprayed fields, and never eat or drink anything you have not identified with certainty.

Eating and using is at your own risk: see the terms of use.

Recipes

• Tapping birch sap (Sap · 1–4 litres a day · 15 min + 1–2 weeks tapping)
• Birch kvass (Fermentation · 2 litres · 15 min + 3–5 days)
• Birch-leaf tea (Tea · 1 cup · 10 min)
• Birch sap and lemon granita (Dish · serves 4 · 15 min + 3–4 hrs freezing)
• Birch leaf bath sachets (Skin and body care · 4 bath sachets · 30 min + 1 week drying)

Good for wildlife

Caterpillars

Host plant: caterpillars of butterflies or moths eat the leaves.

Birds

Berries, seeds or insects as food, or a place to nest.

Ladybirds

Aphids on the plant are food for ladybirds and their larvae.

Did you know?

• Likes wet, peaty soil; hybrids with silver birch occur.
• The downy birch reaches further north than the silver birch; in Iceland it is the only native tree that forms woodland.
• As with silver birch, you can tap birch sap in March, and the bark burns even when damp: ideal for lighting a fire.
• Fly agarics and brown birch boletes are often found under birches: these fungi live in symbiosis with the tree’s roots, exchanging nutrients with it.
• Downy birch grows further north than most trees: in Lapland a subspecies with crooked trunks forms the treeline, where the tundra begins.