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Japanese horseradish Eutrema japonicum

Other Common Name(s):

Previously known as:

  • Alliaria wasabi
  • Cochlearia wasabi
  • Eutrema wasabi
  • utrema japonicum Koidz
  • Wasabia japonica
  • Wasabia wasabi
Phonetic Spelling
juh-PON-ih-kum
Description

Wasabi is an herbaceous perennial, native to Japan and Korea, and is in the same family as cabbage, horseradish, and mustard. Naturally grown along rivers and streams in mountainous areas, it grows well in environments where you would typically find ferns.

The root is a horseradish substitute and the ground rhizome has the pungent spiciness of horseradish and, when finely grated and prepared into an attractive fresh green paste, is a popular condiment in Japan. All parts of the plant are edible, especially the rhizomes, which can take up to three years to mature to a harvest size of 1 inch in diameter.

Plants may be difficult to find in garden centers, and few places are suitable for large-scale wasabi cultivation, which is difficult even in ideal conditions, however, seeds are available online. The best time to plant seeds is late fall to early winter because they need approximately two months of cold temperature before they sprout. Alternatively, seeds can be kept in the refrigerator for two months, and planted outside when the temperature is around 50-55 degrees. Seeds should be soaked in distilled water overnight to soften the outer covering to accelerate germination.

Plant Wasabi in organic, loose, and crumbly soil with good drainage, but good moisture retention. Coarse sand can be added to improve drainage. The best temperature to grow Wasabi is between 46-70 degrees. Sow seeds in heavy shade or under a canopy of trees where it will be cool, moist, and humid. Plant two inches deep, with rows two inches wide, and plant one seed per hole. If planting in a container, thin and transplant to a larger container, at least 10 to 12 inches deep and wide and set the container in a shallow pan of water.  A small amount of slow release 12-12-12 fertilizer is adequate for 3-4 months. Keep plants well-watered, but not standing in water.

Harvest rhizomes by pulling the entire plant out of the ground. The best flavor is derived by grating the cleaned roots within thirty minutes of harvesting, but can be kept refrigerated for a month. Rhizomes can also be dried and ground for a longer shelf life. Wasabi can be propagated from plantlets that grow around the primary plant, or by dividing rhizomes. Wasabi is high in vitamin C, and also contains vitamin A and iron.

Insects, Diseases, and Other Plant Problems:  In some cases, it is susceptible to aphids, alfalfa looper larva, cranefly larva, slugs, leaf spot, root rot, or rhizome rot.  Prune wilted, damaged, or dead leaves to deter pests and diseases.

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#edible plant#perennials#shade garden#herb garden culinary#herbaceous perennials#wet soils tolerant
 
Cultivars / Varieties:
Tags:
#edible plant#perennials#shade garden#herb garden culinary#herbaceous perennials#wet soils tolerant
  • Attributes:
    Genus:
    Eutrema
    Species:
    japonicum
    Family:
    Brassicaceae
    Uses (Ethnobotany):
    Wasabi is studied for medicinal uses, including as an anti-inflammatory, antibacterial, and its potential to reduce osteoporosis, heart disease, and cancer.
    Life Cycle:
    Perennial
    Recommended Propagation Strategy:
    Division
    Seed
    Country Or Region Of Origin:
    South Korea, S Sakhalin to Japan
    Distribution:
    Taiwan, and New Zealand and China. In the United States: Blue Ridge Mountains of North Carolina, rain forest of Oregon Coast, and Tennessee.
    Fire Risk Rating:
    low flammability
    Edibility:
    Wasabi rhizomes are finely grated into a green paste about the consistency of toothpaste, which produces a distinct spicy condiment similar to horseradish and hot mustard. It is served with sushi, salads, poultry, sausage, steamed rice, soups, and a garnish for bread. The leaves, flowers, leafstalks, and sliced rhizomes are used to make a Japanese pickle called wasabi-zuke. Young leaves are used in salads and sandwiches. Note, eating raw leaves can cause diarrhea.
  • Whole Plant Traits:
    Plant Type:
    Herb
    Herbaceous Perennial
    Perennial
    Habit/Form:
    Erect
    Growth Rate:
    Slow
    Maintenance:
    Medium
  • Cultural Conditions:
    Light:
    Dappled Sunlight (Shade through upper canopy all day)
    Deep shade (Less than 2 hours to no direct sunlight)
    Soil Texture:
    Clay
    Loam (Silt)
    Sand
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Good Drainage
    Moist
    Occasional Flooding
    Occasionally Wet
    Available Space To Plant:
    Less than 12 inches
    NC Region:
    Coastal
    Mountains
    Piedmont
    USDA Plant Hardiness Zone:
    7b, 7a, 8b, 8a, 9b, 9a, 10b, 10a
  • Fruit:
    Fruit Type:
    Siliqua
    Fruit Length:
    < 1 inch
    Fruit Width:
    < 1 inch
    Fruit Description:
    The fruit is linear 1/4 to 3/4 inch long and wide, and grooved lengthwise.
  • Flowers:
    Flower Color:
    White
    Flower Inflorescence:
    Raceme
    Flower Value To Gardener:
    Showy
    Flower Bloom Time:
    Spring
    Winter
    Flower Shape:
    Cross
    Flower Petals:
    4-5 petals/rays
    Flower Size:
    < 1 inch
    Flower Description:
    Small clusters of tiny, white, cross shaped flowers (1/4 to 1/10 of an inch) that bloom in late winter to early spring.
  • Leaves:
    Leaf Color:
    Green
    Leaf Value To Gardener:
    Showy
    Leaf Type:
    Simple
    Leaf Arrangement:
    Alternate
    Leaf Shape:
    Cordate
    Ovate
    Leaf Margin:
    Crenate
    Dentate
    Hairs Present:
    No
    Leaf Length:
    3-6 inches
    Leaf Width:
    3-6 inches
    Leaf Description:
    The attractive simple leaves are 3 to 6 inches long and 3 to 7 inches wide, palmately veined, toothed and divided into 3-6 leaflets. Each leaf is borne on long leaf stalks. with small leaflets in between.
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
  • Landscape:
    Landscape Location:
    Pond
    Riparian
    Landscape Theme:
    Asian Garden
    Edible Garden
    Shade Garden
    Water Garden
    Design Feature:
    Mass Planting
    Resistance To Challenges:
    Wet Soil