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Petasites hybridus

common butterbur

Asteraceae Europe, western Asia

Attracts Pollinators Deer Resistant

SunFull Sun – Part Shade

WaterHigh

HardinessZones 4–8

Overview

Petasites hybridus, common butterbur, is a large rhizomatous perennial in the daisy family (Asteraceae) that forms dense colonies in wet ground. In early spring, before the leaves appear, thick flowering spikes 8-16 inches (20-40 cm) tall push up bearing crowded heads of pinkish-mauve flowers. The foliage follows and expands to a large size: rounded, heart-based leaves on stout stalks reach 24-48 inches (60-120 cm) tall, with single blades up to 3 feet (90 cm) across. Plants spread by thick, far-creeping rhizomes and build into extensive single-sex stands, since male and female plants grow separately and most colonies are clones of one sex. It grows along riverbanks, ditches, damp meadows, and roadside seeps on moist, fertile soil. The vigorous rhizomes make it dominant and difficult to remove once established, crowding out smaller plants over wide areas. The leaves and rhizomes contain pyrrolizidine alkaloids that are toxic to the liver if eaten. Topgrowth dies down in autumn, leaving bare rhizomes that resprout in spring.

Native Range

Native across Europe and into western and northern Asia, where it grows in wet, fertile ground along rivers, streams, ditches, and damp meadows. It is widespread in lowland country and has naturalized beyond its range, including parts of North America.

Suggested Uses

Grown in large wild and waterside gardens, on pond and stream banks, and in damp ground where its bold foliage suits expansive naturalistic plantings. Used for erosion control and ground cover on wet banks and ditches. Its spreading rhizomes make it unsuited to small gardens or mixed borders.

How to Identify

In early spring, look for stout pinkish flower spikes emerging from bare ground before any leaves, in damp places near water. As these fade, very large rounded leaves on thick stalks unfurl to form a tall, dense bed. The huge rhubarb-like leaves and riverside, colony-forming habit distinguish Petasites hybridus, with its grey-woolly leaf undersides separating it from butterburs with white-felted undersides.

Appearance

Size & Dimensions

Height2' - 4'

Width/Spread3' - 6'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring

Flowering comes very early, in March and April, ahead of the leaves, when few other plants are in bloom. The pinkish-mauve spikes supply nectar and pollen to early bees and other insects. Most British colonies are male, so seed set is uncommon and spread is mainly by rhizome.

Detailed Descriptions

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam clay silt

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Growth is strongest in full sun to partial shade on permanently moist to wet, fertile soil, such as pond and stream margins, ditches, and damp low ground. The thick rhizomes spread widely and quickly, so an isolated, contained, or naturally bounded site keeps the colony from overrunning neighbours. Once established the plant needs no watering on suitably damp ground and no feeding. It dies back in autumn and resprouts from the rhizome in spring. Removal is difficult because any rhizome fragment left behind regrows. The leaves and rhizomes contain pyrrolizidine alkaloids and are toxic if eaten.

Pruning

Cut down the spent flower spikes and old leaves as they collapse in autumn to tidy the planting. Removing flower heads before seed forms limits the small amount of self-seeding. No other pruning is needed.