Cold hardiness & minimum temperature

Is Navelwort (Umbilicus rupestris)cold hardy? Hardiness zone & min temp

Also called Navelwort, Wall Pennywort, Pennywort, Venus's Navel-wort.

More about navelwort

About Navelwort

Umbilicus rupestris · also called Navelwort, Wall Pennywort · houseplant

Umbilicus rupestris is a fleshy, coin-leaved succulent wildflower native to west European stone walls, cliffs, and hedgebanks from the British Isles to the Mediterranean. Its distinctive navel-like depression in the centre of each round leaf gives it its name. A winter-growing, summer-dormant species, it needs cool, moist winters and dry summer rest.

Cold limit: USDA 7–10 · RHS H5 (-5°C to 20°C)

Watch for — Premature dormancy from heat: Temperatures above 22°C trigger early dormancy. In heated indoor environments the active season may be shorter than expected. Keep the plant in the coolest available spot during spring to extend its growing season.

What navelwort's hardiness rating actually means

Yes — navelwort is genuinely cold hardy. Rated RHS H5 and USDA 7–10, 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 7–10 — 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. Navelwort is built for winter — once established it takes hard frost and snow in its stride.

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

Plant it out within USDA 7–10 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 navelwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Navelwort hardiness — frequently asked questions

Is navelwort cold hardy?

Yes — navelwort is genuinely cold hardy. Rated RHS H5 and USDA 7–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Navelwort is hardy across USDA 7–10; 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 navelwort can survive?

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

What hardiness zone is navelwort?

Navelwort is rated USDA 7–10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can navelwort survive winter outside?

Plant it out within USDA 7–10 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 navelwort 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.