Cold hardiness & minimum temperature

Is Lesser Spearwort (Ranunculus flammula)cold hardy? Hardiness zone & min temp

Also called Lesser Spearwort, Creeping Spearwort.

More about lesser spearwort

About Lesser Spearwort

Ranunculus flammula · also called Lesser Spearwort, Creeping Spearwort · flowering

Lesser Spearwort is a slender, creeping native European aquatic perennial found along pond margins, ditches, and bog edges. It produces small, glossy yellow buttercup flowers from late spring through summer. A good wildflower pond plant that is far less vigorous than its larger relative, Greater Spearwort. Toxic to pets and livestock if ingested.

Cold limit: USDA 4–9 · RHS H7 (-20–26°C)

What lesser spearwort's hardiness rating actually means

Yes — lesser spearwort is genuinely cold hardy. Rated RHS H7 and USDA 4–9, 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 4–9 — 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. Lesser Spearwort is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for lesser spearwort 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 lesser spearwort go outside or overwinter — and where?

Plant it out within USDA 4–9 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 lesser spearwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Lesser Spearwort hardiness — frequently asked questions

Is lesser spearwort cold hardy?

Yes — lesser spearwort is genuinely cold hardy. Rated RHS H7 and USDA 4–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Lesser Spearwort is hardy across USDA 4–9; 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 lesser spearwort can survive?

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

What hardiness zone is lesser spearwort?

Lesser Spearwort is rated USDA 4–9 and RHS H7 — Hardy in the severest European continental winters.

Can lesser spearwort survive winter outside?

Plant it out within USDA 4–9 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 lesser spearwort 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.