Mustard Greens (Brassica juncea)
10 sources cited · Verified
The short answer
- Plant
- Early March to mid August
- Ready in
- 25–50 days
- Site
- 6+ hours of sun, soil pH 6–6.5
- Biggest risk
- Brassica downy mildew
In the UK, mustard greens go in the ground early March to mid August, and are ready to harvest 25–50 days after planting.
Mustard greens (Brassica juncea) — annual.
Timing is the decision that matters most in the UK: there are 4 separate regional sowing windows, ranging from early March in Southern England to early March in Scotland.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Regional Planting Calendar
Quick Facts
At a Glance
Soil & Growing Conditions
Growth Stages
Harvest & Storage
Diseases
Pests
Mustard Greens, a Fast-Growing Peppery Brassica
References
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Directly fetched and verified (canonical URL differs from requested URL /biodiversity/slugs -> redirects to /biodiversity/slugs-and-snails). RHS explicitly advises against slug pellets (even organic) due to wildlife harm, and cites RHS's own controlled trial finding no damage reduction from physical barriers (copper tape, bark mulch, eggshell, grit, wool) -- while also noting some other studies have shown copper barriers to repel slugs, a preserved disagreement rather than a silently resolved one. Details Nemaslug (Phasmarhabditis hermaphrodita) biological control including application temperature range and its lack of effect on snails specifically.
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10 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 mustard greens in the UK?
In Southern England, from early March. In Scotland, wait until early 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 mustard greens?
Sow early March to mid August.
How long do mustard greens take to grow?
Typically 25–50 days, depending on cultivar and growing conditions.
What soil pH do mustard greens need?
A pH of about 6–6.5. 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 mustard greens?
Our data links 3 diseases and 5 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 2026-08-30
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.