Black poplar

Black poplar: how do you recognise it?

Habit

Tree of 20–30 m with a broad, irregular crown about 15 m across; the Lombardy poplar is a narrow column.

Leaves

Alternate, 5–10 cm, triangular to diamond-shaped with a long pointed tip, finely scalloped; no glands at the leaf base and no hairs along the edge. Leaf stalk flattened sideways.

Bark

Dark grey-brown and deeply furrowed, with large burrs and many epicormic shoots.

Flowers

Dark red male catkins in March–April, before the leaves; male and female catkins on separate trees.

Fruit

Female trees release masses of fluffy seeds in May–June.

Difference from hybrid black poplar

Hybrid black poplar has a straight trunk without burrs and a leaf with fine hairs along the edge.

Difference from Lombardy poplar

Lombardy poplar (Populus nigra ‘Italica’) is a narrow columnar form of black poplar, with steeply rising branches.

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

Looks like it, but isn’t

• Hybrid black poplar Populus × canadensis: straight trunk without burrs and a leaf with fine hairs along the edge. Difference from hybrid black poplar
• Lombardy poplar (Populus nigra ‘Italica’): a narrow columnar form of black poplar, with steeply rising branches.

Why grow it?

• A native tree that has become rare: if you have room by a stream or river, you help it by planting one.
• Old, gnarled trees are teeming with life: insects, woodpeckers and hole-nesting birds.
• Grows fast and tolerates flooding.
• The columnar Lombardy poplar is a classic avenue and windbreak tree.
• Bees collect resin from its sticky buds to make propolis.

Black poplar: where does it grow best?

• Full sun.
• Moist to wet soil, ideally by a stream or river or in a wet meadow; any soil type, and it tolerates flooding.
• Allow for 20–30 m in height and a crown of about 15 m: not for an ordinary garden, but for a meadow, a riverbank, a park or a large farmyard.
• Keep it well away from houses, sewers and drains: the roots seek out water.

Light

Full sun

Legal basis

Any garden soil

Moisture

Moist to wet

Size

25 m tall, 15 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• White willow: Together the trees of the riverbank: poplar and pollard willow.
• Alder: Holds the bank together with its roots and fixes nitrogen.
• Guelder rose: A native shrub of wet soil with white flower heads and red berries, for the woodland edge.

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

Black poplar: when and how to plant it?

1. Plant from November to March when the ground isn’t frozen.
2. If you want the wild species, ask for planting stock of native origin; the Lombardy poplar is a single male clone.
3. Poplars also grow from a set: a fresh branch pushed half a metre deep into moist soil in winter.
4. Choose a male tree if you don’t want fluff: female trees shed it in May–June.
5. Protect young trees in a meadow from livestock.

Care

Watering

Never needed on wet soil; young trees on drier soil in dry spells during the first year.

Feeding

Not needed.

Epicormic shoots

The trunk produces many shoots; leave them, or cut them off in winter or summer.

Inspection

Have old trees along roads and paths checked regularly for falling branches.

Tip: Do you have a wet meadow or a stream bank? Plant a male black poplar of native origin there: you help a rare native tree and won’t be bothered by fluff.

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 in winter or summer.

How:

• Little pruning needed. Give a young tree a single leader and remove crossing branches.
• Have old trees along roads and paths checked regularly for falling branches.
• Saw off heavy branches in two stages: first a little further out, then close to the trunk, so that the bark doesn’t tear.

Caution: Hard pruning triggers lots of epicormic shoots on the trunk.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings and sets

Poplars root easily: in winter, push fresh twigs of 20–30 cm or longer sets into moist soil.

Black poplar: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy, and it copes well with winter flooding.
• In winter you can recognise it by its dark, burred trunk full of shoots and its pointed, sticky buds.

Diseases and pests

• Poplar rust: Orange spore pustules on the underside of the leaves in late summer; the leaves drop early. A healthy tree hardly suffers.
• Poplar leaf beetle: A red beetle and its larvae feed on the leaves in summer. Unsightly, but rarely harmful.
• Borers in the trunk: Larvae of the hornet moth and the large poplar longhorn beetle bore tunnels in the wood; sawdust at the base of the trunk gives them away. A healthy old tree usually lives with them.
• Falling branches: Old poplars sometimes drop heavy branches, especially in storms. Have trees along paths and roads checked.

Through the year

• January: Prune if needed; sets and cuttings.
• February: Pruning; planting season when there is no frost.
• March: Dark red catkins; last month for planting.
• May: Fluff from female trees.
• July: Summer pruning: remove epicormic shoots and unwanted branches.
• August: Summer pruning still possible; water young trees in dry spells.
• November: Planting season; pruning can start again.
• December: Pruning; cut sets for new trees.

What can you use it for?

For wildlife

A typical tree of riverbanks and floodplains; old, gnarled trees are teeming with life.

Garden and landscape

The columnar Lombardy poplar is a classic avenue and windbreak tree.

Wood

Light, soft wood for crates, plywood and matches.

Caution: The roots seek out water: do not plant it close to houses, sewers or drains.

Did you know?

• The Lombardy poplar, the narrow column lining roads and canals, is a male clone of black poplar that has been propagated from cuttings since the 18th century.
• Hybrid black poplar is a cross between black poplar and a North American poplar.
• Its light, soft wood was used for crates, plywood and matches.