Cold hardiness & minimum temperature

Is Bulbous Buttercup (Ranunculus bulbosus)cold hardy? Hardiness zone & min temp

Also called Bulbous Buttercup, Bulbous Crowfoot, St Anthony's Turnip.

More about bulbous buttercup

About Bulbous Buttercup

Ranunculus bulbosus · also called Bulbous Buttercup, Bulbous Crowfoot · flowering

Ranunculus bulbosus is a compact, early-flowering perennial native to dry, calcareous grassland across Europe and parts of western Asia, distinguished from other buttercups by its swollen, corm-like stem base (the 'bulb') and reflexed sepals beneath the glossy yellow flowers. It flowers earlier than the meadow buttercup (typically April to June) and then dies back in summer, making it the ideal buttercup for drier, well-drained soils where the other species would struggle. The bulbous base stores energy through the summer drought, and the plant re-emerges from autumn onwards. All parts are toxic to cats, dogs, and horses.

Cold limit: USDA 4-8 · RHS H6 (-25 °C to 25 °C)

What bulbous buttercup's hardiness rating actually means

Yes — bulbous buttercup is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 4-8 — 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 −20 to −15 °C. Bulbous Buttercup is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for bulbous buttercup as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 bulbous buttercup go outside or overwinter — and where?

Plant it out within USDA 4-8 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 bulbous buttercup can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Bulbous Buttercup hardiness — frequently asked questions

Is bulbous buttercup cold hardy?

Yes — bulbous buttercup is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Bulbous Buttercup is hardy across USDA 4-8; 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 bulbous buttercup can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Bulbous Buttercup is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is bulbous buttercup?

Bulbous Buttercup is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can bulbous buttercup survive winter outside?

Plant it out within USDA 4-8 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 bulbous buttercup below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.