Komatsuna (Brassica rapa var. perviridis)
1 sources cited · Verified
The short answer
- Site
- 5+ hours of sun, soil pH 5.6–7.5
- Biggest risk
- Downy mildew
Komatsunas (Brassica rapa var. perviridis) — annual or biennial grown as an annual.
This crop carries an unusually heavy problem load: 2 diseases, 4 pests and 0 nutrient issues are documented for it, so most of the effort in growing it well goes into prevention.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Diseases
Pests
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 5.6 - 7.5 |
| Sunlight | 5-5 hours direct sun |
| Soil texture | fertile, loamy (MorningChores) |
| Drainage | well-drained |
| Lifecycle | annual or biennial grown as an annual |
| Edible parts | leaves |
At a Glance
Soil & Growing Conditions
Water: moisture-retentive, well-draining (MorningChores)
Soil pH range
Span reflects genuine variation between the cited authorities, not a single agreed figure.
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing | 0 | Sow 1/4-1/2in deep, 6in apart with 18-24in between rows, spring through late summer; successive sowings every two weeks (MorningChores). |
| Thinning | 3 | Thin to 4in apart for baby leaves, or 8in for mature plants (Seedy Farm). |
| Leaf growth | 4 | Nitrogen-rich fertiliser at planting, liquid feed 15-20 days after germination; full sun with afternoon shade in harsh climates (MorningChores). |
| Harvest | 8 | Matures in 30-40 days; cut leaving at least 2in of stem for regrowth, usually good for at least two cuttings (MorningChores, Seedy Farm). |
Harvest & Storage
When to pick: Matures in 30-40 days; harvest leaves at any stage. Cut with shears or a sharp knife leaving at least 2 inches of stem so the plant regenerates -- usually at least two cuttings are possible. Pluck any flowers to maintain productivity (MorningChores, Seedy Farm).
Komatsuna, Leaf to Table
References
-
Optimal temperature range 45-80F; bolts in heat but can't handle a hard frost either -- some cold-tolerant hybrids tolerate below 10F. Full sun, with afternoon shade in harsh climates. Soil pH 5.6-7.5, moisture-retentive, fertile, loamy, well-draining; nitrogen-rich fertiliser at planting, liquid feed 15-20 days after germination. Sow 1/4-1/2in deep, spaced 6in apart with 18-24in between rows; sow spring to late summer (year-round for some hybrids), every two weeks for a constant supply. Matures in 30-40 days; harvest leaves at any stage, the plant regenerates for continuous picking; pluck flowers to maintain productivity. PESTS: flea beetles, cabbage loopers, aphids. DISEASES: leaf spot, downy mildew (grey fluff on leaves, treat with organic fungicide and improve spacing for airflow), black leg.
1 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.
Frequently Asked Questions
What soil pH do komatsunas need?
A pH of about 5.6–7.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect komatsunas?
Our data links 2 diseases and 4 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
Almost everything on this page resolves to your own frost dates rather than the calendar — the last spring frost moves by roughly two months between zone 3 and zone 10. The USA Garden Planner works from your zone so the timing is already decided before the season starts.
Get the USA Garden Planner →Instant PDF download · Written for US growing conditions
Last verified 2026-08-29
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.