Cold hardiness & minimum temperature

Is Indian Mustard 'Tendergreen' (Brassica juncea 'Tendergreen')cold hardy? Hardiness zone & min temp

Also called Tendergreen mustard spinach, komatsuna-type mustard.

More about indian mustard 'tendergreen'

About Indian Mustard 'Tendergreen'

Brassica juncea 'Tendergreen' · also called Tendergreen mustard spinach, komatsuna-type mustard · edible

'Tendergreen', also called mustard spinach, is a vigorous, smooth-leaved mustard grown for mild, spinach-like greens. Quick to mature in about 40 days, it tolerates heat and cold better than most mustards and resists bolting. Sow in succession for tender salad leaves or cooked greens through spring, autumn, and into mild winters.

Cold limit: USDA Annual; grown in zones 2-11 as a cool-season crop · RHS H5 (tolerates light frost, more heat-tolerant than most mustards) (10-26°C)

What indian mustard 'tendergreen''s hardiness rating actually means

Yes — indian mustard 'tendergreen' is genuinely cold hardy. Rated RHS H5 and USDA Annual; grown in zones 2-11 as a cool-season crop, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA Annual; grown in zones 2-11 as a cool-season crop — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Indian Mustard 'Tendergreen' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for indian mustard 'tendergreen' as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can indian mustard 'tendergreen' go outside or overwinter — and where?

Plant it out within USDA Annual; grown in zones 2-11 as a cool-season crop and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when indian mustard 'tendergreen' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Indian Mustard 'Tendergreen' hardiness — frequently asked questions

Is indian mustard 'tendergreen' cold hardy?

Yes — indian mustard 'tendergreen' is genuinely cold hardy. Rated RHS H5 and USDA Annual; grown in zones 2-11 as a cool-season crop, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Indian Mustard 'Tendergreen' is hardy across USDA Annual; grown in zones 2-11 as a cool-season crop; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature indian mustard 'tendergreen' can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Indian Mustard 'Tendergreen' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is indian mustard 'tendergreen'?

Indian Mustard 'Tendergreen' is rated USDA Annual; grown in zones 2-11 as a cool-season crop and RHS H5 — Hardy in most of the UK and in cold winters.

Can indian mustard 'tendergreen' survive winter outside?

Plant it out within USDA Annual; grown in zones 2-11 as a cool-season crop and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to indian mustard 'tendergreen' below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.