Wasabia japonica - Japanese Horseradish

Family:	Cruciferae
Habit:	Perennial
Height:	0.3
Width:	0.2
Synonyms:	Eutrema wasabi.
Range:	E. Asia - Japan.

Wasabia japonica (Japanese Horseradish) is a Perennial which grows to a height of 0.3m and a width of 0.2m . It has a hardness rating of 8.
Japanese Horseradish will flower in October to November. The flowers from this plant are hermaphrodite (has both male and female organs) and they are pollinated by

Soil Information

Japanese Horseradish 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
Japanese Horseradish prefers soils

Ideal Planting Locations

Japanese Horseradish can grow in semi or areas with no shade.

Wet places and by streams, in lowland and mountain areas[58]. Usually found near the coast[200].

Planting places suited to this plant described below.

• Is a pond plant
• A bog garden plant

Cultivation Details

Prefers a position in wet soil or shallow water. The best quality roots are produced from plants growing in semi-shade in clear running spring water at a temperature between 11 - 14°c[200]. This species is cultivated in eastern Asia for its edible root which is used in much the same way as horseradish[58], it takes 3 - 5 years to produce marketable roots[116]. The roots are finger-thick and up to 18cm long[206].

Edible Uses*

* See disclaimer
Edible Rating: 2/5
Root - a horseradish substitute[2, 46, 58, 61, 105]. The fleshy rhizomes are finely grated and prepared into an attractive fresh green paste which is much used as a condiment in Japan[183]. It is considered to have a distinct flavour and pungency that is superior to horseradish, Armoracia rusticana[183]. The pungency rapidly deteriorates once the root has been cut[200]. Roots of plants 15 - 24 months old are best[238]. Leaves, flowers and petioles - cooked[105, 179, 200]. The leaves, flowers, leafstalks and freshly sliced rhizome are soaked in salt water and then mixed with saki lees to make a popular Japanese pickle called 'wasabi-zuke'[183]. The following analysis is said to belong to the leaves but it looks more like a root analysis[K]. The leaves contain about 6.1% protein, 0.2% fat, 22.3% carbohydrate, 1.3% ash[179].

• Condiment - the various plants that are used as flavourings, either as herbs, spices or condiments.
• Leaves -
• Root - includes bulbs, corms, tubers, rhizomes etc.

Medicinal Uses*

* See disclaimer
Medicinal Rating: 1/5
The root is a pungent warming herb that stimulates the digestion[238]. It is used internally as an antidote to fish poison[238]. (This probably refers to food poisoning caused by eating fish[K]).

• Digestive - Aids digestion.

Propagation

Seed - sow spring in a greenhouse and keep the seed permanently moist[238]. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the greenhouse for their first year. Stand the pots in shallow water to ensure the plants do not dry out. Plant them out in late spring or early summer. Division in spring as the plant comes into growth. Very easy, the larger divisions can be planted out direct into their permanent positions. We have found that it is best to pot up smaller divisions and grow them on in light shade in a greenhouse or cold frame until they are growing away well. Plant them out in the summer or the following spring.

Known Hazards

None known

Other Uses

None known

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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