Cold hardiness & minimum temperature

Is Pilea pumila (Pilea pumila)cold hardy? Hardiness zone & min temp

Also called clearweed, coolwort, richweed.

More about pilea pumila

About Pilea pumila

Pilea pumila · also called clearweed, coolwort · houseplant

Pilea pumila, or clearweed, is a soft annual native to North America and Asia, named for its translucent, almost see-through green stems and toothed, nettle-shaped leaves that sting nobody. A shade-loving woodland herb more often found wild than potted, it suits cool, moist, semi-shaded spots and self-seeds readily. It is harmless and pet-safe.

Cold limit: USDA 3-8 (hardy annual; self-seeds outdoors) · RHS H5 (13-24°C)

What pilea pumila's hardiness rating actually means

Yes — pilea pumila is genuinely cold hardy. Rated RHS H5 and USDA 3-8 (hardy annual; self-seeds outdoors), 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 3-8 (hardy annual; self-seeds outdoors) — 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. Pilea pumila is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for pilea pumila 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 pilea pumila go outside or overwinter — and where?

Plant it out within USDA 3-8 (hardy annual; self-seeds outdoors) 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 pilea pumila can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Pilea pumila hardiness — frequently asked questions

Is pilea pumila cold hardy?

Yes — pilea pumila is genuinely cold hardy. Rated RHS H5 and USDA 3-8 (hardy annual; self-seeds outdoors), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Pilea pumila is hardy across USDA 3-8 (hardy annual; self-seeds outdoors); 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 pilea pumila can survive?

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

What hardiness zone is pilea pumila?

Pilea pumila is rated USDA 3-8 (hardy annual; self-seeds outdoors) and RHS H5 — Hardy in most of the UK and in cold winters.

Can pilea pumila survive winter outside?

Plant it out within USDA 3-8 (hardy annual; self-seeds outdoors) 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 pilea pumila 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.