Hybrid black poplar

Hybrid black poplar: how do you recognise it?

Habit

Tree of 25–35 m with a straight trunk and an open, fairly broad crown about 15 m across.

Leaves

Alternate, triangular to diamond-shaped, 7–10 cm, with a straight base and finely toothed edge. The leaf stalk is flattened sideways.

Bark

Grey, deeply furrowed lengthways.

Flowers

Red male catkins in March.

Fruit

Fluffy seeds in May on female trees.

Difference from black poplar

Black poplar is the rare native parent, with a trunk covered in large burrs.

Flowering: March–April · Harvest and fruit: January–March · Pruning: July–August and November–February

Looks like it, but isn’t

• Black poplar (Populus nigra): a rare native parent; trunk with large burrs.

Why grow it?

• Very fast-growing: a tall windbreak within a few years.
• Rows of poplars along roads and fields are typical of our landscape.
• The leaves rustle in the slightest breeze.
• Copes with wet, heavy soil, where many other trees struggle.

Hybrid black poplar: where does it grow best?

• Full sun.
• Moist, rich soil, such as clay or loam along streams; it tolerates wet feet.
• Allow for 25–35 m in height and a crown of about 15 m: only for a large property, a meadow or a windbreak along a field, not for a garden.
• Keep well away from houses, drains and sewers – at least as far as the tree will grow tall: older trees drop branches and the roots seek out water.

Light

Full sun

Legal basis

Any garden soil

Moisture

Moist to wet

Size

30 m tall, 15 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Alder: A native tree for the same wet soil: together a shelterbelt that stays standing after the poplars are felled.
• Hawthorn: A thorny native shrub that makes the windbreak dense at the bottom.
• Hazel: Fills the understorey of a shelterbelt and provides nuts for squirrels and mice.

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

Hybrid black poplar: when and how to plant it?

1. Plant from November to March when the ground isn’t frozen.
2. Plant young trees or rooted cuttings; in a windbreak, space them about 6–8 m apart.
3. If you don’t want fluff, choose a male clone such as ‘Robusta’.
4. On a windy site, secure a young tree to a stake and water it during dry spells in the first year.

Care

Watering

Only in dry spells during the first year.

Crown lifting

On young trees, remove the side branches gradually for a straight, branch-free trunk.

Checking

Have old trees along roads, paths and buildings checked regularly for dead wood and cracks.

Feeding

Not needed: on rich soil it grows fast enough already.

Tip: Want a quick windbreak on a large property? Alternate hybrid black poplars with native shrubs and trees such as hawthorn, hazel and alder: the screen becomes dense at the bottom and stays standing when the poplars are later felled. If you are looking for a native poplar, choose the black poplar or the aspen.

Hybrid black poplar: when to prune it?

Pruning months: July–August and November–February.

When: Dead, diseased and broken branches can be removed at any time of year. Formative pruning or crown lifting in winter or summer.

How:

• On young trees, remove side branches gradually for a straight trunk; take off only a few branches at a time and keep at least the top half of the tree as crown.
• Cut branches off just outside the branch collar, without leaving a stub.
• Have old trees along roads checked regularly.

Caution: Topping a poplar (sawing off the crown) does not make an oversized tree safer: the new shoots are weakly attached and break off easily later.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

Hardwood cuttings 20–30 cm long from one-year-old shoots, taken in winter and pushed into the ground, root readily. That way the clone is preserved.

Hybrid black poplar: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• After a winter storm, check whether any broken or split branches are hanging in the crown.

Diseases and pests

• Poplar rust: Orange spore pustules on the underside of the leaves from late summer; the leaves drop early. A healthy tree survives it.
• Branch failure: The wood is brittle: old trees drop branches in storms, but sometimes also on still summer days. Have them checked.
• Large poplar longhorn: The larvae of a large longhorn beetle bore tunnels in the trunk of young trees; you see sawdust at the base. The trunk is weakened and can snap.
• Roots in pipes: The roots get into leaking sewers and drains. Prevent it by keeping enough distance.

Through the year

• January: Pruning and crown lifting in winter.
• February: Pruning; planting season when there is no frost.
• March: Red catkins; still planting season; taking cuttings.
• April: Leaves emerge.
• May: Fluff from female trees.
• July: Summer pruning: lift the crown and remove dead branches.
• August: Crown lifting; look for rust on the leaves.
• October: Yellow autumn colour.
• November: Planting season; pruning can start again.
• December: Pruning and crown lifting.

What can you use it for?

Wood

Light wood for clogs, matches, fruit crates and plywood.

Garden and landscape

Fast-growing windbreak tree, planted in rows along roads and fields.

Caution: Older trees drop branches, and the roots seek out water: don’t plant too close to houses or drains.

Edible and useful

Resin (January–March)

The sticky, balsam-scented winter buds, from January to March, shortly before they open. Gather them from branches brought down by a storm or removed when pruning; do not strip branches bare. The resin in the buds makes a fragrant oil and salve for dry, rough skin.

Storing

Fresh buds can be frozen or put straight into oil. The oil and salve keep for about a year in a cool, dark place.

Caution: Not for eating: use the buds externally only. If you are allergic to propolis, balsam of Peru or aspirin, do not use the salve; always test it first on a small patch of skin and do not apply it to open wounds. The resin is sticky: use old jars and cloths. Only gather branches on your own land or with permission.

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

Recipes

• Poplar-bud salve (Skin and body care · ± 120 ml · 1 hr + 2–4 weeks infusing)
• Poplar bud oil (Skin and body care · ± 250 ml · 15 min + 4–6 weeks steeping)
• Wood wax with poplar resin (Other · ± 130 ml (2 jars of 70 ml) · 20 min + 2 hrs setting)

Good for wildlife

Caterpillars

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

Did you know?

• Fast-growing hybrid, planted on a massive scale for wood for clogs, matches and fruit crates.
• The Dutch name ‘Canada poplar’ is misleading: the cross arose in Europe, between a North American poplar and our black poplar.
• Poplars grown for timber are often felled after only about 20–25 years.
• Despite its name it does not come from Canada: it is a cross between the native black poplar and the North American Populus deltoides that arose spontaneously in Europe in the 18th century.
• Poplars are propagated from cuttings, so every tree of one cultivar, such as ‘Robusta’, is a genetically identical clone. Male clones, which produce no fluff, were often preferred.