<em>Petasites</em>: planting, cultivation, maintenance

Description and botany

Le Petasite est une plante vivace rhizomateuse de la famille des Asteracées, comme la marguerite et l’aster. Il pousse naturellement sur les rives des cours d’eau, dans les fossés humides, les sous-bois, et jusqu’à 1 500 m d’altitude environ du Nord de l’Europe, en particulier en France, mais aussi d’Asie, d’Afrique du Nord et d’Amérique du Nord.

The Petasite is a rhizomatous perennial plant of family Asteraceae, related to oxeye daisy and aster. It grows naturally on riverbanks, in damp ditches and woodland understorey, and up to around 1,500 m altitude in northern Europe, particularly France, but also in Asia, North Africa and North America.

Le genre comprend une quinzaine d’espèces dont certaines comme le Petasites hybridus (syn.Petasites officinalis), sont si communes qu’il n’est pas rare de les rencontrer en bordures de fossés ou près de lieux humides ou dans les zones montagneuses de notre pays qu’elles colonisent allègrement.

The genus includes about fifteen species, some of which, such as Petasites hybridus (syn. Petasites officinalis), are so common that they are frequently found at ditch edges, near wet places or in mountainous zones where they readily colonise.

Chez les petasites, on distingue les espèces à petites feuilles comme le Petasites fragrans qui est parfumé, les espèces à grandes feuilles comme le Petasites albus ou pétasite blanc et les espèces géantes telles que les Pétasites japonais géants (Petasites japonicus var. Giganteus) et le Petasites hybridus, également appelé Grand pétasite ou encore pétasite hybride. Ce dernier, qui est également est une plante médicinale reconnue et est également affublé d’un bon nombre de surnoms comme “Chapelière”, “Grand pas d’âne”, “Chapeau du diable”, “Herbe à teigneux”, “Herbe-à-la-peste”, ou encore “Rhubarbe des marais”.

Among petasites, there are small-leaved species such as Petasites fragrans, noted for its scent, large-leaved species such as Petasites albus or white petasite, and giant species like giant Japanese petasites (Petasites japonicus var. giganteus) and Petasites hybridus, also known as Great petasite or hybrid petasite. The latter is also a recognised medicinal plant and carries many folk names such as “Hatter”, “Great Donkey’s Step”, “Devil’s Hat”, “Scabby-herb”, “Plague-herb” or “marsh rhubarb”.

On rencontre le Pétasite également parfois sous le nom anglais de “butterbur”, car ses feuilles immenses servaient autrefois à envelopper les mottes de beurre.

Petasite is also sometimes known by English name “butterbur”, as its huge leaves were once used to wrap pats of butter.

De croissance rapide, tous les petasites forment des touffes fortement tapissantes. Selon les espèces, la hauteur des plantes varie de 0,30 cm à 0,50 m de hauteur pour les couvre-sols jusqu’ à 1,50 m de haut pour les immenses spécimens de Pétasites. Mais, même chez les moins hauts des pétasites, l’envergure peut atteindre facilement plus d’1 m à maturité. Cette vivace se propage facilement, s’étalant souvent bien au-delà des limites imparties grâce à ses épais rhizomes traçants, pouvant devenir envahissante si on ne contrôle pas un peu son expansion.

Fast-growing, all petasites form dense, spreading clumps. Depending on species, plant height ranges from 0.30–0.50 m for groundcover types up to 1.50 m for the gigantic petasites. Even the shorter types can easily reach more than 1 m spread at maturity. This perennial spreads readily, often extending well beyond intended limits via thick running rhizomes, and can become invasive unless its spread is controlled.

Petasite hybridus – botanical illustration

Le pétasite est surtout intéressant pour ses grandes feuilles luxuriantes, car sa floraison est peu spectaculaire. Elle paraît la plupart du temps, avant le feuillage en fin d’hiver. De mars à mai, selon le climat, parfois plus tôt, les  hampes florales bien dressées souvent de couleur pourpre, émergent au ras du sol avant les nouvelles feuilles basales.  Elles se déploient en grappes terminales ovoïdes composées de petits capitules larges de 1 cm à 2 cm de diamètre. Chaque capitule rassemble de nombreuses fleurs tubulées terminées par 5 dents et des fleurons périphériques ligulés, prolongés un long pétale. Le Pétasite est une plante dioïque, c’est à dire qu’il existe des pieds femelles ou mâles qui se différencient par la forme de ces fleurons, plus ou moins allongés. Ces capitules sont entourés par des bractées vert clair ou pourpres selon les espèces.

Petasite is chiefly valued for its large, lush leaves rather than for spectacular flowering. Flowering usually appears before the foliage in late winter. From March to May, depending on climate and sometimes earlier, erect flower stalks, often purplish, emerge at ground level before the new basal leaves. They open into ovoid terminal clusters made up of small heads 1–2 cm diameter. Each head bears numerous tubular flowers ended by five teeth and peripheral ligulate florets extended into a long petal. Petasite is a dioecious plant, with distinct male and female plants, differing by shape of these florets, which may be more or less elongated. The heads are surrounded by pale green or purplish bracts depending on species.

Ces inflorescences globuleuses et trapues, portées par des tiges feuillées  sont hautes de 10 à 25 cm, parfois véritablement colossales chez les pétasites géants.

These compact, globular inflorescences borne on leafy stems are 10–25 cm high, sometimes truly colossal in giant petasites.

Rosées, pourprées (Petasites hybridus), blanches (Petasites albus) ou blanc jaunâtre, elles sont odorantes et diffusent un délicieux parfum sucré de vanille. Riches en nectar, elles attirent au cœur de l’hiver les insectes pollinisateurs affamés.

Rosy, purplish (Petasites hybridus), white (Petasites albus) or creamy white, the flowers are fragrant and give off a delightful sweet vanilla scent. Rich in nectar, they attract hungry pollinating insects in the depth of winter.

La floraison est suivie par l’apparition d’une végétation vigoureuse et spectaculaire. Le feuillage est le principal attrait de cette majestueuse plante couvre-sol. Caduc, ce feuillage disparaît en hiver et ne réapparaît qu’assez tardivement au printemps bien après les capitules. En avril, à partir du puissant rhizome souterrain, des rosettes de feuilles basales portées par un long pétiole commencent à émerger. La plante produit alors une touffe ample de feuilles plus ou moins grandes selon les espèces et variétés. Ces feuilles spectaculaires grandissent au fil des semaines pour devenir gigantesques en début d’été.

Flowering is followed by emergence of vigorous and spectacular foliage. The foliage is the main attraction of this majestic groundcover. Deciduous, the leaves die back in winter and reappear rather late in spring, well after the flower heads. In April, from the powerful underground rhizome, rosettes of basal leaves borne on long petioles begin to emerge. The plant then forms a generous clump of leaves, size varying with species and cultivar. These dramatic leaves expand over weeks to become gigantic by early summer.

Les feuilles du Pétasite se caractérisent par leur forme, réniforme (en forme de rein) à cordiforme (en forme de cœur) atteignant 6 cm pour le Petasites fragrans jusqu’à 1 mètre de diamètre pour les espèces géantes comme le Petasites japonicus var. giganteus et le Petasites hybridus, qui sont eux les véritables “chapeliers” ! Car, le Petasite doit son nom à ses feuilles au limbe arrondi, “petasos” désignant en grec le chapeau rond à larges bords que portaient les pâtres grecs.

Petasite leaves are notable for shape, from reniform (kidney-shaped) to cordate (heart-shaped), reaching 6 cm for Petasites fragrans up to 1 metre across in giant species such as Petasites japonicus var. giganteus and Petasites hybridus, the true “hatters”! Indeed, Petasite owes its name to rounded leaves — Greek “petasos” referred to a round hat with a broad brim worn by Greek shepherds.

Elles présentent des bords plus ou moins régulièrement dentés et un revers pubescent et parfois un dessus également laineux et vert grisâtre. Souple et duveteux, ce feuillage revêt de belles nuances de verts allant du vert mat au vert foncé satiné. Certaines formes exhibent un somptueux feuillage irrégulièrement panaché de jaune d’or à l’instar du Petasites hybridus ‘Variegatus’.

Leaves have more or less regular dentate margins with a pubescent underside and sometimes a woolly, grey-green upper surface. Soft and downy, the foliage shows attractive shades from . Some forms display splendid irregular variegation of golden yellow as in Petasites hybridus ‘Variegatus’.

En fin d’été, le feuillage des grands pétasites devient si ample qu’il se développe souvent au point d’étouffer toutes les autres plantes alentours, leur laissant rarement une chance de survie.

By late summer, foliage of large petasites can become so abundant that it often overwhelms neighbouring plants, rarely leaving them a chance to survive.

Doté d’une belle rusticité au moins jusqu’à-25°C, le Pétasite s’installe un peu partout dans notre pays, sauf peut-être en climat méditerranéen, trop sec en été. S’il tolère un peu tous les types de terre calcaire, neutre ou acide (à l’exception des terrains caillouteux), sa préférence va vers une terre de sous-bois riche, constamment fraîche ou même très humide.

With good hardiness down to at least −25°C, Petasite establishes readily across the country, except perhaps in Mediterranean climates that are too dry in summer. While it tolerates calcareous, neutral or acidic soils (except stony ground), it prefers a rich woodland-type soil that remains constantly cool or very damp.

Development of an inflorescence of Petasite hybridus

C’est une plante d’ombre ou de mi-ombre et de fraîcheur, idéale pour donner une allure sauvage dans un jardin d’ombre, près des points d’eau ou en bordure de sous-bois humides où elle forme des buissons de verdure à elle seule parfois de plus d’1m de haut. Il est parfait également en couvre-sol en bordure, milieu ou en fond de massif semi-ombrés auxquels il apporte une luxuriance dépaysante.

It is a plant for shade or partial shade and cool conditions, ideal for creating a wild look in a shade garden, near water features or at edges of damp woodland where it can form bushes of greenery alone sometimes over 1 m high. It is also excellent as groundcover at fronts, centres or backs of semi-shaded borders, adding an exotic lushness.

Le Pétasite possède des propriétés médicinales reconnues depuis des siècles. À partir de ses feuilles ou des rhizomes, on tire un extrait exempt des substances toxiques que renferme la plante naturellement.  Il est utilisé pour soulager les migraines et réduire les symptômes des rhinites allergiques. Au XVIIe siècle, il était prescrit contre la toux, l’asthme et pour soigner les plaies et les brûlures.

The Petasite has medicinal properties recognised for centuries. Extracts free from naturally occurring toxic compounds are obtained from leaves or rhizomes. These extracts are used to relieve migraines and reduce symptoms of allergic rhinitis. In the 17th century it was prescribed for coughs, asthma and to treat wounds and burns.

Au Japon, les longs pétioles du Petasites japonicus se consomment comme des légumes.

In Japan, long petioles of Petasites japonicus are eaten as vegetables.

Main species and varieties

Genus comprises around fifteen species that differ mainly in the size of their leaves, ranging from 6 cm to 1 m in diameter, and in the colour of their flowers.

Most popular

Petasites hybridus

Meet Giant pétasite! Its fragrant flowering is followed by the emergence of very large heart-shaped leaves measuring 50 cm to 1 metre in diameter. It brings a lush touch to a very damp woodland understorey or to large, slightly neglected areas of a garden that it can colonise with ease.

• Flowering time April, May
• Height at maturity 50 cm

See the product sheet

Our favourites

Petasites albus

Also called white pétasite and, like all pétasites, capable of spreading up to 1.5 m across at ripeness. Particularly useful for bringing a touch of exoticism and light to damp, unrewarding areas of a large garden.

• Flowering time April to June
• Height at maturity 40 cm

See the product sheet

Planting

Where to plant petasite?

Hardy to -25°C, petasite will establish itself throughout France, except perhaps in Mediterranean regions, which are too hot and dry in summer, because it prefers shaded locations and cool, moist soils that retain water well. It will tolerate summer heat provided soil remains moist and cool in depth during summer, because petasite does not like drought.

It thrives in shade or partial shade, sheltered from burning sun, under the foliage of deciduous trees that will give it the coolness it needs.

Undemanding regarding soil type, provided it is cool, moist or even waterlogged, it nevertheless prefers soil rich in organic matter, light, in which it will develop with remarkable vigour. It will also grow very well in heavy, clay soil.

Before planting, remember that petasite can be invasive because once established, it will spread without concern for its neighbours… It is perfect for covering large areas. If you want to control its spread, plant it in drier soil in partial shade where sun predominates over shade; it will be much less vigorous and less likely to overflow, while still maintaining a good presence!

It is the ideal plant for a water garden and a shade garden, for woodland understorey or a wet meadow. It is perfect for colonising ground in a cool understorey, margins of a moist bank, a pond edge or a lake. It is useful to limit adventive species in the most unpromising, very wet corners or marshy areas of a large garden. In smaller spaces, its tendency to spread must be contained because it will nibble into surrounding ground, ignoring boundaries.

When to plant petasite?

Planting petasite can be carried out in spring (March to May) or in autumn (September to November).

How to plant petasite?

As you will have understood, petasite has a vigorous nature that can become invasive! Space out plantings well: at maturity, a single plant will easily reach a spread of 1 m. Do not be fooled by its small size on receipt of your bucket! Allow 3 plants per m² and water until established and throughout the first year: it needs a lot of water to settle.

• Dig a hole 2 to 3 times wider than the rootball
• Fork soil deeply
• Add a good shovelful of well-rotted compost or manure
• Fill in and firm down
• Water generously
• Mulch around base to preserve moisture during summer

If you wish to limit expansion of its running rootstocks you can also try containing it in a closed basket. Discover our detailed explanations in this step-by-step: contain an invasive plant.

Care and maintenance

Le Petasite is not a delicate plant, it requires almost no maintenance and is free from diseases.

Ensure soil remains moist: it creates large, exotic-style displays until frosts, but must be watered often and deeply as it must never be short of water. Mulch in May to reduce watering and evaporation.

Petasite often exceeds gardeners’ expectations, so to prevent it becoming invasive, each spring after flowering, make a spade cut around the clump to remove wandering rootstocks that would spread too far.

Every two years in spring, spread a few shovelfuls of compost over the stump if desired.

Propagation

Butterbur has a natural propensity to spread quickly. However, to obtain new young plants we recommend division in spring or in autumn, after flowering, or propagation of rootstocks.

Division

• Using a spade, lift part of the stump
• With a spade stroke, take pieces of rootstock that have at least two leafy shoots
• Replant these pieces immediately into cool, moist soil enriched with compost
• Water generously to keep the soil moist

Taking butterbur cuttings

Simply cut fragments of rootstock about 10 cm long with 1 or 2 buds and push them into moist soil so that they root quickly.

Pairing butterburs with other plants in the garden

With its oversized leaves and flowers in soft hues, Petasite is an indispensable perennial in shade gardens and at the water’s edge. Whether over 1 m tall or groundcover, it fits into all shaded settings as a large drift under trees or in a cool rockery. Although it unquestionably holds its own, it lends itself to luxuriant combinations with other perennials of wet banks or shade-loving perennials.

An example of a planting combination: Matteuccia struthiopteris, Astilbe japonica ‘Deutschland’, Euphorbia palustris and Petasite hybridus

At the edge of a pond, pair it with Gunnera, Rodgersias or Darmera, goat’s beard, marsh euphorbias and the graceful astilbes, meadowsweet, lysimachias, knotweeds…

On the edge of a cool, damp understorey, in a “jungle” spirit, it will form luxuriant plant masses surrounded by its shade companions such as hostas and ferns.

In a wild garden at the edge or centre of a shaded bed, it will be an attractive partner for Solomon’s seals, Veronicastrum virginicum, ligularias and silver candles.

It will also be very attractive alongside Asian primroses or the hardy begonia grandis evansiana.

As its foliage reappears quite late in spring, pair it with spring bulbs such as snowflakes, chionodoxa, crocus, hyacinths or iris reticula, Galanthus which will occupy the space in late winter before Petasite leaves attain the characteristic size that defines them!