Eutrema japonicum
Wasabi
Common names: Japanese horseradish
At a glance
- Light
- Partial shade
- Spacing
- 30 cm, rows 40 cm
- Lifespan
- Perennial
- Sowing
- Mar–Apr
- Harvest
- Oct–Dec
- Hardiness
- Cold damage below −5 °C
- Water need
- High
Photo: Qwert1234 · CC BY-SA 3.0 · Source
This description was machine-translated.
Description
Wasabi (Eutrema japonicum) is a perennial herb native to the cool stream beds of Japanese mountain forests. It thrives in consistently cool, shaded, and permanently moist conditions, preferring gently running water around the roots. The plant is cultivated mainly for its sharp rhizome, which is harvested after two to three years of growth and freshly grated for use. Successful cultivation in a garden or balcony container requires a shaded, wind‑protected location, such as under trees or on the north side of a greenhouse. Direct sunlight and drying soil are detrimental, but the reward is a rhizome that rivals commercial wasabi powder in flavor and aroma.
Care instructions
Keep the soil evenly moist to wet throughout the year, using a peat‑rich, humus‑laden substrate with good drainage to prevent root rot. Choose a semi‑shaded to shaded spot; direct noon sun scorches the leaves. Mulch to retain soil moisture and keep roots cool. Fertilize sparingly with mature compost in spring and summer; additional feeding is usually unnecessary. Protect young plants in the first winter with a leaf mulch; mature rhizomes tolerate light frost down to about, 5 °C without issue.
The care notes were machine-translated from German.
Garden year
SowingMar–Apr
HarvestOct–Dec
Germination
- Soil temperature
- from 8 °C, ideally 15 °C
- Days to sprout
- 21 to 60 days
- Light
- Needs light to sprout
- Sowing depth
- Press in, don't cover
- How to start
- Start indoors, then plant out
Soil & site
Soil pH
Soil type
moist, humus-rich, well-drained, nutrient-rich
Wasabi likes to be permanently moist, but never waterlogged. A humus-rich, loose soil with good drainage imitates the stream banks of its Japanese homeland. Loosen and enrich poor or compacted soil beforehand with mature compost.
Wasabi belongs botanically to the brassicas, so the same break from growing applies here as for cabbage crops.
Feeding
Medium feeder
Months
Apr–Jul
From April to July, feed every few weeks with well-matured compost or diluted plant liquid feed. Wasabi rewards a steady, gentle supply of nutrients more than strong one-off feeds. From August, reduce feeding so the plant can grow calmly into the winter half of the year.
Overwintering
Wasabi is hardy and easily survives mild frosts outdoors, as long as the root area stays protected from frost. A mulch layer of leaves or straw keeps the soil evenly moist and protects the roots on cold nights. In container cultivation the plant overwinters best cool and sheltered, for example in a cold greenhouse.
Propagation
Methods
- From seed
- Division
- Offsets
The most reliable way to propagate wasabi is by dividing established clumps, ideally in spring as it starts to shoot. Side shoots and offsets at the base of the mother plant keep growing well on their own after being separated. Sowing is possible, but much slower, and germination needs cool, evenly moist conditions over several weeks. For quick harvest success, divisions are the more dependable choice.
Companion planting
Good neighbors
legume family (Fabaceae)
particularly well establishedLeguminous plants collect nitrogen in the soil, from which Brassicaceae benefit as heavy feeders.
For example PeaBush beanPole beanBroad beanSnow peaWrinkled pea and 36 more species in the catalogue
Source: classic companion planting (DACH-Gartenpraxis)
carrot family (Apiaceae)
You can pair celery and dill with all Brassicaceae because they repel the cabbage whitefly with their scent, a proven companion.
For example CarrotCeleriacDillParsleyFlorence fennelCoriander and 21 more species in the catalogue
Source: Bio-Gärtnerei Mixed-culture Practice
mint family (Lamiaceae)
You will notice that the intense scent of basil, thyme, and others confuses the cabbage whitefly and keeps it away from the cabbage family.
For example LavenderThymeBasilRosemarySageHyssop and 43 more species in the catalogue
Source: bio-gardening intercropping practice
nasturtium family (Tropaeolaceae)
Nasturtium serves as a trap plant for you. Aphids and cabbage whiteflies prefer it over the brassicaceae next to it.
For example NasturtiumMashua
Source: Trap plant practice in organic horticulture
Companion planting is partly traditional gardening lore. Where the reason is known, it is given.
Some of these explanations were machine-translated.
For your garden
Grow Wasabi yourself
Gartenkern tells you when frost is coming, when to sow and when to harvest, for your location.
Free, no time limit
Notes from real gardens
What other gardeners have written down about this variety, anonymous and voluntary.
No notes shared yet. Will you be the first to write one down?