Cold hardiness & minimum temperature

Is 'Red Russian' Kale (Brassica napus var. pabularia 'Red Russian')cold hardy? Hardiness zone & min temp

Also called Red Russian kale, Ragged Jack kale.

More about 'red russian' kale

About 'Red Russian' Kale

Brassica napus var. pabularia 'Red Russian' · also called Red Russian kale, Ragged Jack kale · edible

Red Russian is a tender, frilled, flat-leaved kale with grey-green oak-shaped leaves and purple-red stems and veins that intensify in cold. Botanically a Brassica napus type, it is milder and more delicate than curly kale, excellent as both baby leaf and mature greens. Very cold-hardy and quick to crop, it tolerates poorer soils than most brassicas.

Cold limit: USDA 3-9 (very cold-hardy; survives hard frosts and light snow) · RHS H5 (7-24°C)

Watch for — Bolting: Spring-sown plants checked by cold or heat may run to flower, ending leaf production. Keep moisture even and sow main crops in summer for autumn and winter picking.

What 'red russian' kale's hardiness rating actually means

Yes — 'red russian' kale is genuinely cold hardy. Rated RHS H5 and USDA 3-9 (very cold-hardy; survives hard frosts and light snow), 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 3-9 (very cold-hardy; survives hard frosts and light snow) — 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. 'Red Russian' Kale is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for 'red russian' kale 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 'red russian' kale go outside or overwinter — and where?

Plant it out within USDA 3-9 (very cold-hardy; survives hard frosts and light snow) 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 'red russian' kale can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

'Red Russian' Kale hardiness — frequently asked questions

Is 'red russian' kale cold hardy?

Yes — 'red russian' kale is genuinely cold hardy. Rated RHS H5 and USDA 3-9 (very cold-hardy; survives hard frosts and light snow), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. 'Red Russian' Kale is hardy across USDA 3-9 (very cold-hardy; survives hard frosts and light snow); 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 'red russian' kale can survive?

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

What hardiness zone is 'red russian' kale?

'Red Russian' Kale is rated USDA 3-9 (very cold-hardy; survives hard frosts and light snow) and RHS H5 — Hardy in most of the UK and in cold winters.

Can 'red russian' kale survive winter outside?

Plant it out within USDA 3-9 (very cold-hardy; survives hard frosts and light snow) 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 'red russian' kale 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.