Petasites japonicus - Sweet Coltsfoot

Family:	Compositae
Habit:	Perennial
Height:	0.6
Width:	1.5
Synonyms:	Nardosmia japonica.
Range:	E. Asia - China, Japan, Korea. Naturalized in Britain.

Petasites japonicus (Sweet Coltsfoot) is a Perennial which grows to a height of 0.6m and a width of 1.5m . It has a fast growth rate. It has a hardness rating of 5.
Sweet Coltsfoot will flower in August. the seeds ripen from September
The flowers from this plant are dioecious (each plant is either male or female, thus both genders need to be present to seed) and they are pollinated by Insects

Soil Information

Sweet Coltsfoot will grow in light (sandy),medium (loamy),hard (clay) soil. It is not necessary for the soil to be well drained.
The soil prefers the following PH / acid levels :
- pH of less than 6, Acidic soils
- pH between 6 and 8, Neutral soils
- pH greater than 8, Basic soils
Sweet Coltsfoot prefers soils

Ideal Planting Locations

Sweet Coltsfoot can grow in full, semi shaded areas and areas with no shade.

Moist woods and thickets[58].

Planting places suited to this plant described below.

• Grows within a woodland garden
• Grows on a sunny edge
• Works within dappled Shade
• Grows in a shady edge
• Is suited to a deeply shaded location
• Can spread to cover ground and will out compete weeds
• Suits a meadow
• A bog garden plant

Cultivation Details

Succeeds in ordinary garden soil[1], but prefers a deep fertile humus-rich soil that is permanently moist but not stagnant, succeeding in shade, semi-shade or full sun[200]. Requires a moist shady position[187]. Plants can be grown in quite coarse grass, which can be cut annually in the autumn[233]. A very invasive plant, too rampant for anything other than the wild garden[187, 200]. Its roots are very difficult to eradicate[200]. The sub-species P. japonicus giganteus has huge leaves up to 1.5 metres across on stems 2 metres tall[187]. It has a poorer flavour than the species type[206]. Sometimes cultivated in E. Asia as a food plant[1, 58]. Dioecious, male and female plants must be grown if seed is required.

Edible Uses*

* See disclaimer
Edible Rating: 3/5
Leaf stalks - cooked and used like rhubarb[1, 2, 46, 116]. The stems can be up to 1.2 metres long[104]. They can be boiled and seasoned, pickled and used in winter soups or preserved in miso[183]. They can be boiled, dipped in cold water then peeled and baked - they have a pleasant fragrant taste[206]. Flower buds cooked or used as a flavouring[1, 22, 46, 61, 105]. A slightly bitter yet agreeable flavour[116, 206], they are much prized in Japan[183]. They can be eaten whilst still green with miso or boiled down in soy sauce[183]. The young flowering stems can be eaten cooked[206].

• Flowers -
• Stem - this often intergrades into leaves.

Medicinal Uses*

* See disclaimer
Medicinal Rating: 2/5
The plant (though the exact part of the plant used is not specified) is antiasthmatic, antispasmodic, expectorant and poultice[147]. 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[147].

• Antiasthmatic - Treats asthma.
• Antispasmodic - Relaxes muscular spasms and cramps, calming nervous irritation.
• Expectorant - Clears phlegm from the chest by inducing coughing.
• Poultice - A moist, usually warm or hot, mass of plant material applied to the skin in the treatment of burns etc.

Propagation

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.

Known Hazards

None known

Other Uses

The leaves of the sub-species P. japonicus giganteus are used as umbrellas by Japanese children[187]. The leaf stalks can be used as walking sticks[206]. Plants can be grown as ground cover in damp shady places[206]. They are too invasive for most gardens and should only be used where they have plenty of room[208].

• Ground cover - Usually low growing plants that can be grown with other plants, especially shrubs and trees, to prevent the growth of weeds.
• Miscellany - A rag-bag of items that are difficult to categorise.

Cultivars

no recorded cultivars

References

Flora of Japan. (English translation)
Ohwi. G.
Author: Ohwi. G.
Rating:
Publisher : The standard work. Brilliant, but not for the casual reader.
Date of Publication : 1965

The New RHS Dictionary of Gardening. 1992.
Huxley. A.
Author: Huxley. A.
Rating:
Publisher : Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
Date of Publication : 1992

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