Dutchman’s pipe

Dutchman’s pipe: how do you recognise it?

Habit

Woody, twining climber (it winds around supports), 6–8 m tall and up to 4 m wide; loses its leaves in autumn.

Leaves

Large, heart-shaped, 10–30 cm, soft green and overlapping like tiles; yellow in autumn.

Flowers

Curved, pipe-shaped flowers of 3–4 cm, yellow-green with a brown-purple mouth, hidden under the foliage. May to July.

Support

Twines around wires, ropes and slats; the stems become thick and heavy and need a sturdy support.

Roots

Vigorous root system that appreciates a deep, humus-rich planting site.

Flowering: May–July · Plants: March–April and October · Pruning: February–March

Why grow it?

• Huge heart-shaped leaves give a lush, jungle-green screen in half shade or sun.
• Grows fast to about 8 m tall: ideal for a pergola, arbour or high wall.
• Fully hardy to about −25 °C and happy in ordinary garden soil.
• Curious pipe-shaped flowers: a talking point in the garden.
• The dense wall of leaves gives privacy and shade in summer.

Dutchman’s pipe: where does it grow best?

• Half shade to shade is fine; also in sun if the soil stays moist.
• Humus-rich, moisture-retentive soil: sand, loam or clay, from acid to chalky; normal to moist.
• Sheltered from strong wind, which tears the large leaves.
• Give it a sturdy support: a pergola, tensioned wires or a strong trellis 3–4 m wide.
• Plant at least 50 cm from a wall or fence.

Light

Sun, partial shade and shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal or wet

Size

8 m tall, 4 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Hosta: Large leaves at the base, in the same half shade.
• Ferns: Fresh, green underplanting for the shade beneath the climber.
• Japanese anemone: Flowers in late summer beneath the rising wall of leaves.
• Lady’s mantle: A soft, yellow flowering edge at the front.

Dutchman’s pipe: when and how to plant it?

Plant in March–April and October.

1. Plant in March–April or in October, when the soil is not frozen or waterlogged.
2. Dig a hole twice as wide as the root ball and mix in compost.
3. Set the plant at the same depth as in the pot, 30–40 cm from the wall, and lead the stems towards the support.
4. Tie the stems loosely to wires or slats until they twine around the support themselves.
5. Water generously straight away, even if it is raining.
6. Spread a 5 cm layer of leaf mould mulch round the base.

Care

Water

In the first year weekly in dry weather, afterwards only in long dry spells; then give a good soaking at the base.

Feeding

In March compost or organic fertiliser round the base.

Mulching

A layer of leaf mould keeps the base cool and moist.

Support

Check every year that the support is sturdy: the plant becomes heavy.

Training

Guide young shoots to the support at first; after that it twines by itself.

Tip: Want to see the strange pipe-shaped flowers? Gently lift the foliage in May–June: they are hidden in there. Provide a sturdy support from the start, it avoids problems later.

Dutchman’s pipe: when to prune it?

Pruning months: February–March.

When: In February–March, before new shoots start. It tolerates hard pruning.

How:

• Cut out dead, thin and damaged stems.
• Shorten overlong or rampant shoots to the desired shape.
• To rejuvenate it, cut a few old stems back to about 1 m above the ground; it will shoot again.
• Thin it out so that light and air reach between the leaves.

Caution: Wear gloves: all parts are poisonous. Do not leave prunings lying where children or animals can reach them.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Semi-ripe cuttings

July–August: 15 cm cuttings with 2–3 nodes in sandy compost under plastic, warm and bright. Rooting is slow.

Layering

March–April: lay a long stem in the soil and peg it down; separate and replant after a year.

Dutchman’s pipe: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy, to about −25 °C: no protection needed even in hard Belgian winters.
• It loses its leaves in autumn and shoots again in April. The fallen leaves make useful mulch.
• Young plants get a thick layer of mulch round the base in their first winters.
• A late night frost in April can scorch young shoots: cover them with fleece if a cold night is forecast.

Diseases and pests

• No flowers: Young plants only flower after a few years and the flowers are hidden under the foliage. Patience and a spot in half shade or sun help.
• Slugs: Young shoots are eaten in April. Collect slugs in the evening or set traps.
• Aphids and spider mites: On young shoots in dry, hot weather. Spray off with water and water at the base.
• Scorched or torn leaves: Caused by strong wind or drought in a sunny spot. Provide shelter and even watering.

Through the year

• January: Rest. Check the support and ties.
• February: Prune before growth starts.
• March: Finish pruning. Give compost. Plant.
• April: Plant. Mulch. Watch for slugs and late frost.
• May: Flowering starts, under the foliage. Guide the shoots.
• June: Flowering. Water in dry weather.
• July: Flowering. Take semi-ripe cuttings.
• August: Cuttings. Water in dry weather.
• September: The foliage begins to change colour.
• October: Plant. Yellow autumn colour. Leave fallen leaves as mulch.
• November: Leaf fall. Check the support.
• December: Rest.

Edible and useful

Not edible. All parts of Dutchman’s pipe are poisonous: they contain aristolochic acids, which permanently damage the kidneys and can cause cancer, even in small amounts taken in over a long time. Related species were once used as medicinal herbs, and herbal remedies containing aristolochia have caused serious kidney disease; they are therefore banned. Never make teas, herbal remedies or anything else to swallow from it, and do not eat any of it. Keep children and pets away from the plant and its pipe-shaped flowers, and wear gloves when pruning. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• The flowers are tiny prisons: a fly is attracted, slides into the tube and is held by hairs until the flower has been pollinated and lets it go.
• In North America the plant feeds the caterpillars of a swallowtail butterfly (Battus philenor).
• The name comes from the shape of the flower, which looks like an old-fashioned, curved pipe.