Komatsuna (Brassica rapa var. perviridis)
1 sources cited · Verified
The short answer
- Plant
- Mid March to late August
- Site
- 5+ hours of sun, soil pH 5.6–7.5
- Biggest risk
- Downy mildew
In the UK, komatsunas go in the ground mid March to late August.
Komatsunas (Brassica rapa var. perviridis) — annual or biennial grown as an annual.
Timing is the decision that matters most in the UK: there are 4 separate regional sowing windows, ranging from mid March in Southern England to mid March in Scotland.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Regional Planting Calendar
| Region | Sow |
|---|---|
| Southern England | mid March to late August |
| Midlands | mid March to late August |
| Northern England | mid March to late August |
| Scotland | mid March to late August |
Southern England - detail & sources
MorningChores gives a spring-through-late-summer sowing window rather than UK-specific dates; this window is applied across all four sub-regions rather than inventing a north/south gradient the source does not support.
Midlands - detail & sources
MorningChores gives a spring-through-late-summer sowing window rather than UK-specific dates; this window is applied across all four sub-regions rather than inventing a north/south gradient the source does not support.
Northern England - detail & sources
MorningChores gives a spring-through-late-summer sowing window rather than UK-specific dates; this window is applied across all four sub-regions rather than inventing a north/south gradient the source does not support.
Scotland - detail & sources
MorningChores gives a spring-through-late-summer sowing window rather than UK-specific dates; this window is applied across all four sub-regions rather than inventing a north/south gradient the source does not support.
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).
Diseases
Pests
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
When should I sow komatsunas in the UK?
In Southern England, from mid March. In Scotland, wait until mid March. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.
When do I sow komatsunas?
Sow mid March to late August.
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
Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.
Get the UK Garden Planner →Instant PDF download · Written for UK 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.