Dutchman's pipe

Sun

Full sun to partial shade; afternoon shade is helpful in hot summers.

Water

Keep the soil consistently moist but not waterlogged, especially while establishing and during hot, dry weather.

Soil

Fertile, humus-rich, well-drained soil; tolerates clay if drainage is adequate.

Height

20-30 ft (6-9 m)

Spread

10-20 ft (3-6 m)

Flowers

Late spring to early summer; small, curved, yellow-green flowers with a purple-brown opening, largely concealed by leaves.

Foliage

Large, overlapping, heart-shaped green leaves form a dense screen; autumn colour is usually modest yellow.

Growth

Fast once established.

Care needed

Medium

• Pollinators
• Cold hardy
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   2 ft (0.6 m)

2. After 1 year

   3 ft (1.1 m)

3. After 2 years

   5 ft (1.5 m)

4. After 3 years

   6 ft (1.8 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

the US and Canada

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Install a strong pergola, trellis or wire framework before planting; mature stems become heavy.
• Water deeply during dry spells, particularly in the first two growing seasons.
• Apply a 2-3 in (5-8 cm) organic mulch each spring, keeping it clear of the stems.
• Top-dress with compost in spring; avoid heavy feeding that encourages excessive growth.
• Guide young stems onto supports and remove unwanted suckers or stems that root where they touch the ground.

Pruning. Prune in late winter or early spring, removing dead or tangled stems and shortening growth that has outgrown its support. Renovate an overgrown plant by cutting back some of the oldest stems near the base; hard pruning may reduce flowering that year.

Late winter

Prune while leafless and inspect the support and wall fixings.

Spring

Plant when the soil is workable, water thoroughly and mulch the root area.

Late spring

Guide new shoots onto their support before they tangle with nearby plants.

Summer

Water during dry spells and trim shoots that obstruct paths, windows or gutters.

Early autumn

Remove unwanted suckers and rooted trailing stems before they establish.

Late autumn

Clear fallen leaves from paths and check exposed roots have mulch before winter.

• Train over a substantial pergola to provide dense summer shade and admit winter light.
• Cover a sturdy fence or freestanding screen to create seasonal privacy.
• Grow on wires set away from a wall, leaving space for airflow and maintenance.
• Use as a bold leafy backdrop to ferns, hostas and other shade-tolerant planting.

Garden styles it suits: Woodland, Traditional, Victorian, Secret garden, Green on green and Wildlife garden.

Plant it with: Hosta, Lady fern, Astilbe, Solomon's seal, Siberian bugloss and Wild geranium.

Wildlife: A larval food plant for the pipevine swallowtail in North America. Small flies pollinate the unusual flowers. Do not assume it is a suitable host for butterflies outside its native region; seek local advice before planting for Australian birdwing butterflies.

• Leaf scorch or wilting in dry soil: water deeply and mulch; provide afternoon shade in hot locations.
• Spider mites in hot, dry conditions: rinse leaf undersides regularly and avoid letting the roots dry out.
• Excessive growth and tangled stems: prune annually and remove unwanted suckers before they spread.
• Pipevine swallowtail caterpillars can strip leaves in North America: tolerate feeding where possible and avoid spraying this host plant.

All parts should be treated as poisonous to people, cats, dogs and horses if eaten. Aristolochia contains aristolochic acids, which can cause severe, potentially irreversible kidney damage and are carcinogenic. Never use it as food or herbal medicine; seek urgent medical or veterinary advice after ingestion.

• Woolly Dutchman's pipe (Aristolochia tomentosa)

  Has conspicuously hairy young shoots and woolly leaf undersides; Dutchman's pipe has largely hairless mature leaves.

• Elegant Dutchman's pipe (Aristolochia elegans)

  A frost-tender climber with much larger, conspicuous, purple-and-white patterned flowers, rather than small flowers hidden beneath the leaves.

• Southern catalpa (Catalpa bignonioides)

  Has similarly large, heart-shaped leaves but grows as a self-supporting tree, with showy white flower clusters and long, bean-like seed capsules.

Dutchman's pipe refers to the curved flowers resembling old-fashioned smoking pipes, while macrophylla means large-leaved.

Propagation. Layer a low-growing stem in spring and separate it after it has rooted well. Softwood cuttings taken in early summer can also root; seed usually needs a period of cold, moist stratification.

Accepted botanical name

Aristolochia macrophylla

In the US and Canada

Native in the lower 48 states. Introduced in Canada.

Native range

Georgia, Kentucky, Maryland, New York, North Carolina, Ontario, Pennsylvania, Romania, South Carolina, Tennessee, Vermont and Virginia.

Measured

Soil pH 7 to 7.5. Average height 1000 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.