Smoke-tree

Smoke-tree: how do you recognise it?

Habit

Broad, rounded shrub or small tree of 3–5 m, often multi-stemmed.

Leaf

Alternate, 4–8 cm, round to oval, untoothed and hairless, on a long stalk; green or dark purple, with fiery autumn colour.

Bark

Greyish-brown; crushed twigs smell resinous.

Flower

Tiny, yellowish-green flowers in large, loose clusters in June–July.

Smoke and fruit

The stalks of the sterile flowers grow into long, pink to grey hairs: the ‘smoke’, from July to September. Among them sit a few small drupes.

Difference from ninebark

Ninebark has lobed, toothed leaves and domed white flower heads.

Difference from cherry plum ‘Nigra’

Cherry plum ‘Nigra’ is a small tree with toothed, purple leaves and pink blossom in March.

Flowering: June–July · Pruning: March

Looks like it, but isn’t

• Ninebark Physocarpus opulifolius: lobed, toothed leaves and domed white flower heads. Difference from ninebark
• Cherry plum (Prunus cerasifera ‘Nigra’): a small tree with toothed, purple leaves and pink blossom in March.

Why grow it?

• Colourful foliage from spring to autumn, especially in the purple forms.
• Striking ‘smoke’ in summer that lasts for weeks.
• One of the finest autumn colours in the garden: orange, red and purple.
• Tough on dry, poor soil, where many other shrubs struggle.

Smoke-tree: where does it grow best?

• Full sun: there the leaves colour best and it forms the most plumes. In shade, purple forms turn greenish.
• Any free-draining soil, including chalky, sandy or stony ground; on poor, dry soil the autumn colour is brightest.
• Avoid soil that stays wet in winter: it declines there.
• Allow 3–4 m width; lovely as a specimen in a lawn or at the back of a sunny border.

Light

Full sun

Legal basis

Any garden soil

Moisture

Dry

Size

4 m tall, 4 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• English lavender: Both love full sun and dry soil; lavender fills the base with scent and bees.
• Broom: Yellow flowers in May next to the dark purple leaves, on the same poor, dry soil.
• Butterfly bush: Flowers in summer, just as the plumes appear, and also likes a sunny, dry spot.
• Ornamental grasses: Their airy flower heads echo the plumes, and yellow or silvery grass stands out well against purple leaves.

Good and bad companions

Best kept away from

• Do not plant under the dense crown of these trees: norway spruce, european silver fir, nordmann fir, douglas fir, yew, horse chestnut, norway maple, sycamore

Smoke-tree: when and how to plant it?

1. Plant from a pot in autumn or spring, not in frost or drought.
2. Loosen the soil well; manure or lots of compost is not needed: on rich soil it grows more lushly and colours less.
3. Plant at the same depth as in the pot and firm the soil well.
4. Water in dry spells during the first year; after that it looks after itself.

Care

Watering

In dry spells during the first year; rarely needed after that, as it copes well with drought.

Feeding

Not needed; too much feeding gives long shoots and duller autumn colour.

Shape

Let it grow freely: that way it keeps its natural, broad shape and produces the most plumes.

Dead branches

Cut out suddenly wilted or dead branches well into healthy wood (see verticillium wilt under problems).

Tip: Purple forms such as ‘Royal Purple’ colour darkest in full sun; the yellow-leaved ‘Golden Spirit’ lights up a sunny border and turns orange in autumn. Pick a few plumes in August: they dry beautifully for a dried arrangement.

Smoke-tree: when to prune it?

Pruning months: March.

When: End of winter (March).

How:

• For the plumes, let it grow freely: only remove dead, damaged or crossing branches.
• If you mainly want large, richly coloured leaves, cut the branches back to 2–3 buds every spring: you get large leaves, but no plumes.
• Reduce an oversized shrub gradually: every year, saw a few of the oldest branches off at the base.

Caution: Hard pruning costs you that summer’s plumes, as the flower clusters form on last year’s wood. So choose between plumes and large leaves.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Layering

In spring, bend a low branch down to the ground, nick the underside lightly and cover it with soil; after a year you can sever it and replant it.

Softwood cuttings

In June–July, take soft cuttings of 10 cm and root them under plastic; they do not always take.

Smoke-tree: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• In winter it stands bare, with greyish-brown branches; wait until March to prune.

Diseases and pests

• Verticillium wilt: In summer whole branches suddenly wilt, and the wood beneath shows discoloured streaks. Cut them back well into healthy wood and disinfect your secateurs; do not plant another smoke-tree or a maple in the same spot.
• Powdery mildew: White coating on the leaves in late summer, especially on purple forms in a stuffy corner. Usually harmless; give it an airy, sunny spot.
• No plumes: A young shrub flowers little at first; hard pruning or overly rich soil also reduces flowering. Let it grow freely and do not feed it.

Through the year

• March: Prune: remove dead wood, or cut back hard for large leaves; planting.
• April: Leaves unfurl, deep red in the purple forms.
• June: Flowering: small yellowish-green clusters, visited by bees.
• July: The plumes appear.
• August: Plumes at their best; water young plants in dry spells.
• October: Fiery autumn colour in orange, red and purple.
• November: Plant pot-grown shrubs.

What can you use it for?

Garden and landscape

Specimen shrub for a sunny, dry spot; the purple forms give colour from spring to autumn.

For wildlife

Bees visit the small flowers.

Did you know?

• Its wood once yielded a yellow dye for wool, leather and silk.
• It belongs to the same family as the pistachio, the cashew and the mango.
• The ‘smoke’ is not made of flowers, but of the lengthened stalks of sterile flowers.