Cold hardiness & minimum temperature

Is Hosta (Hosta spp.)cold hardy? Hardiness zone & min temp

Also called Plantain lily, Funkia, Hosta lily.

More about hosta

About Hosta

Hosta spp. · also called Plantain lily, Funkia · flowering

Hosta (plantain lily) is a hardy shade-loving foliage perennial grown in borders and pots, with lily-like flowers on tall scapes in summer. It is mildly toxic to pets: the ASPCA lists Hosta as toxic to cats, dogs and horses because saponins cause vomiting, diarrhoea and depression. Keep nibbling pets away from plantings.

Cold limit: USDA USDA zones 3-9 · RHS H7 (fully hardy in the UK) (10-24°C)

Watch for — Crown and root rot: Cold, waterlogged or poorly drained soil — particularly over winter — causes the dormant crown to rot, with shoots yellowing and collapsing at the base.

What hosta's hardiness rating actually means

Yes — hosta is genuinely cold hardy. Rated RHS H7 and USDA USDA zones 3-9, 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 USDA zones 3-9 — 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. Hosta is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for hosta 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 hosta go outside or overwinter — and where?

Plant it out within USDA USDA zones 3-9 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 hosta can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Hosta hardiness — frequently asked questions

Is hosta cold hardy?

Yes — hosta is genuinely cold hardy. Rated RHS H7 and USDA USDA zones 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Hosta is hardy across USDA USDA zones 3-9; 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 hosta can survive?

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

What hardiness zone is hosta?

Hosta is rated USDA USDA zones 3-9 and RHS H7 — Hardy in the severest European continental winters.

Can hosta survive winter outside?

Plant it out within USDA USDA zones 3-9 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 hosta 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.