Cold hardiness & minimum temperature

Is The Rocket Ligularia (Ligularia × hessei 'The Rocket')cold hardy? Hardiness zone & min temp

Also called The Rocket ligularia, tall spiked ligularia.

More about the rocket ligularia

About The Rocket Ligularia

Ligularia × hessei 'The Rocket' · also called The Rocket ligularia, tall spiked ligularia · flowering

'The Rocket' is a clump-forming bog perennial grown for its dramatic black stems carrying tall, narrow spires of lemon-yellow flowers in mid to late summer above large triangular, toothed leaves. It demands constantly moist, rich soil and shade from hot afternoon sun, wilting badly the moment its roots dry. A reliable damp-border and pondside specimen.

Cold limit: USDA 4-8 (hardy garden perennial) · RHS H7 (-1 to 24°C)

What the rocket ligularia's hardiness rating actually means

Yes — the rocket ligularia is genuinely cold hardy. Rated RHS H7 and USDA 4-8 (hardy garden perennial), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4-8 (hardy garden perennial) — 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 below about −20 °C. The Rocket Ligularia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for the rocket ligularia as it gets too cold:

It tolerates winter lows to about −20 °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 the rocket ligularia go outside or overwinter — and where?

Plant it out within USDA 4-8 (hardy garden perennial) 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 the rocket ligularia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

The Rocket Ligularia hardiness — frequently asked questions

Is the rocket ligularia cold hardy?

Yes — the rocket ligularia is genuinely cold hardy. Rated RHS H7 and USDA 4-8 (hardy garden perennial), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. The Rocket Ligularia is hardy across USDA 4-8 (hardy garden perennial); 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 the rocket ligularia can survive?

Minimum survivable temperature is roughly below about −20 °C. The Rocket Ligularia is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is the rocket ligularia?

The Rocket Ligularia is rated USDA 4-8 (hardy garden perennial) and RHS H7 — Hardy in the severest European continental winters.

Can the rocket ligularia survive winter outside?

Plant it out within USDA 4-8 (hardy garden perennial) 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 the rocket ligularia below its minimum temperature?

It tolerates winter lows to about −20 °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.