How to Grow Mizunas Canada | Care, Pests & Disease Control

Diseases

Pests

Quick Facts

At a Glance

Soil & Growing Conditions

Water: moist but well-drained; prefers cooler conditions especially in summer (RHS)

Growth Stages

Harvest & Storage

When to pick: Baby greens from 4-6 weeks after germination, once leaves reach 4-6in tall; fuller heads at 6-8 weeks (Harvest to Table). Very cold-hardy, harvestable well into winter under row covers or cold frames.

Mizuna, Field to Blanched Bunch

A distinct Japanese lineage

Mizuna is a genetically distinct lineage of Brassica rapa unique to Japan -- a different subspecies from both Pak Choi and Choi Sum already grown on this site, despite sharing the same parent species.

Deeply serrated, not smooth

The dark green, deeply serrated leaf is what distinguishes mizuna from its close relative mibuna, which has simple spatulate leaves instead.

Slow to bolt, fast to mature

Harvest to Table: unlike many leafy greens, mizuna is slow to bolt in hot weather, while reaching maturity from seed in about 40 days.

Hardy well into winter

RHS rates it H5, hardy throughout most of the UK even in severe winters; Harvest to Table notes it survives unprotected to -6C, and to -12C under row covers or in a cold frame.

Grown as an annual, though technically biennial

Mizuna is biennial by nature but is grown and harvested entirely within its first year as a fast, compact rosette -- flowering, as shown here, marks the end of its useful cropping life.

References

1. Harvest to Table -- Tier 2, used only for sowing succession/germination-temperature detail RHS does not cover, not contradicted by it - How to Plant, Grow, and Harvest Mizuna

   Sow in spring as soon as soil can be worked, about two weeks after the last frost; germinates in soil as cool as 40F (4C), taking 4-7 days at 45-85F (7-29C). Sow every three weeks for succession harvests; grows from seed to maturity in about 40 days. Sow again near end of summer for an autumn/early winter harvest. Harvest begins 3-6 weeks after germination: baby greens at 4-6 weeks once leaves reach 4-6in tall, fuller heads at 6-8 weeks. Extremely cold-hardy, harvestable well into winter under row covers or cold frames; unprotected plants survive light frost to about -6C (21F), row-covered or cold-framed plants to -12C (10F). Grown in USDA zones 3-10. Slow to bolt in hot weather compared to many leafy greens.

2. RHS (Royal Horticultural Society) - Brassica rapa subsp. nipposinica var. laciniata

   Hardiness H5 (hardy throughout most of the UK even in severe winters, -15 to -10C). Full sun or part shade. Soil: chalk, clay, loam or sand; moist but well-drained; alkaline or neutral pH; tolerates both exposed and sheltered sites. Height and spread 0.1-0.5m (20cm rosettes noted in first year). Time to maturity 1 year (biennial, but harvested in first year as a fast-growing compact plant). Grow in firm, fertile soil. Oriental greens are usually very hardy but prefer moist, cooler conditions, especially in summer. Propagate by seed. PESTS: susceptible to flea beetle, small white butterfly caterpillars, cabbage root fly, pigeons, snails, mealy cabbage aphid, though damage isn't usually severe once established. DISEASES: may develop brassica downy mildew, white blister, or club root (particularly in previously-cropped soil) -- named directly for this species, not inferred.

2 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.