Sweet Coltsfoot, Japanese sweet coltsfoot, Butterbur
Petasites japonicus
Family: Asteraceae or Compositae
What it is like
Bloom Color: White. Main Bloom Time: Early spring, Late winter. Form: Spreading or horizontal, Upright or erect.
Petasites japonicus is a PERENNIAL growing to 0.6 m (2ft) by 1.5 m (5ft in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower in February, and the seeds ripen in March. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). and is pollinated by Insects. The plant is not self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in full shade (deep woodland) semi-shade (light woodland) or no shade. It prefers moist or wet soil.
Height (m): 0.6
Where it is found
Moist woods and thickets.
E. Asia - China, Japan, Korea. Naturalized in Britain.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 3
Leaf stalks - cooked and used like rhubarb. The stems can be up to 1.2 metres long. They can be boiled and seasoned, pickled and used in winter soups or preserved in miso. They can be boiled, dipped in cold water then peeled and baked - they have a pleasant fragrant taste. Flower buds cooked or used as a flavouring. A slightly bitter yet agreeable flavour, they are much prized in Japan. They can be eaten whilst still green with miso or boiled down in soy sauce. The young flowering stems can be eaten cooked.
Stem: this often intergrades into leaves.
Medicine
Rating: 2
The plant (though the exact part of the plant used is not specified) is antiasthmatic, antispasmodic, expectorant and poultice. A decoction is used in the treatment of chronic coughing and pulmonary 'deficiency', laboured or difficult breathing and asthma, constant sputum formation and pulmonary tuberculosis.
Antiasthmatic: Treats asthma.
Antispasmodic: Relaxes muscular spasms and cramps, calming nervous irritation.
Expectorant: Clears phlegm from the chest by inducing coughing.
Miscellany: Various medicinal actions that need more clarification.
Poultice: A moist, usually warm or hot, mass of plant material applied to the skin in the treatment of burns etc.
Other
Rating: 1
The leaves of the sub-species P. japonicus giganteus are used as umbrellas by Japanese children. The leaf stalks can be used as walking sticks. Plants can be grown as ground cover in damp shady places. They are too invasive for most gardens and should only be used where they have plenty of room.
Miscellany: A rag-bag of items that are difficult to categorise.
Food Forest: Plants for Edible Forest Gardens and Food Forests.
Ground cover: Ground Cover
How it is grown
Landscape Uses:Container, Ground cover, Massing, Woodland garden. Succeeds in ordinary garden soil, but prefers a deep fertile humus-rich soil that is permanently moist but not stagnant, succeeding in shade, semi-shade or full sun. Requires a moist shady position. Plants can be grown in quite coarse grass, which can be cut annually in the autumn. A very invasive plant, too rampant for anything other than the wild garden. Its roots are very difficult to eradicate. The sub-species P. japonicus giganteus has huge leaves up to 1.5 metres across on stems 2 metres tall. It has a poorer flavour than the species type. Sometimes cultivated in E. Asia as a food plant. Dioecious, male and female plants must be grown if seed is required. Special Features:Attractive foliage, Not North American native, Invasive, Wetlands plant, Flower characteristics are unknown. Petasites japonicus giganteus (Petasites japonicus subsp. giganteus F.Schmidt ex Kitam) is a larger version of Petasites japonicus commonly know as giant fuki. It can grow in similar hardiness zones to fuki but can grow in wetter conditions and tolerate more sun. It can grow to 5 ft (1.5m). The plant is heat tolerant in zones 9 through 5. (Plant Hardiness Zones show how well plants withstand cold winter temperatures. Plant Heat Zones show when plants would start suffering from the heat. The Plant Heat Zone map is based on the number of "heat days" experienced in a given area where the temperature climbs to over 86 degrees F (30°C). At this temperature, many plants begin to suffer physiological damage. Heat Zones range from 1 (no heat days) to 12 (210 or more heat days). For example Heat Zone. 11-1 indicates that the plant is heat tolerant in zones 11 through 1.) For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is a runner spreading indefinitely by rhizomes or stolons. The root pattern is rhizomatous with underground stems sending roots and shoots along their length.
Propagating it: Seed - we have no information on this species but suggest sowing the seed in a cold frame as soon as it is ripe or in early spring. Only just cover the seed and do not allow the compost to dry out. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. Division succeeds at almost any time of the year. Very easy, larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Shady Edge; not Deep Shade; Ground Cover; Meadow; Bog Garden;
Habit: Perennial
Hardiness: 5-9
Growth: Fast
Soil: Light (sandy), medium, heavy (clay)
Shade: Full shade, semi-shade, no shade
Moisture: Moist, wet
Things to keep in mind
Its other names
Local names
Synonyms
Nardosmia japonica.