Cold hardiness & minimum temperature

Is Good Luck Plant (Oxalis deppei)cold hardy? Hardiness zone & min temp

Also called Iron Cross Oxalis, Lucky Clover, Four-leaf Sorrel.

More about good luck plant

About Good Luck Plant

Oxalis deppei · also called Iron Cross Oxalis, Lucky Clover · flowering

Good Luck Plant is a Mexican bulbous Oxalis with distinctive four-leaflet leaves marked with a purple-brown iron cross pattern, and clusters of funnel-shaped rosy-pink flowers in summer. Popular as a novelty houseplant and gift plant. Contains soluble oxalates — mildly toxic to pets. Edible leaves are used in salads in small quantities by humans in Mexico.

Cold limit: USDA 6-10 (with winter mulch in colder zones) · RHS H4 (15-25°C)

What good luck plant's hardiness rating actually means

Yes — good luck plant is genuinely cold hardy. Rated RHS H4 and USDA 6-10 (with winter mulch in colder zones), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 6-10 (with winter mulch in colder zones) — 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 −10 to −5 °C. Good Luck Plant is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for good luck plant as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 good luck plant go outside or overwinter — and where?

Plant it out within USDA 6-10 (with winter mulch in colder zones) 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 good luck plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Good Luck Plant hardiness — frequently asked questions

Is good luck plant cold hardy?

Yes — good luck plant is genuinely cold hardy. Rated RHS H4 and USDA 6-10 (with winter mulch in colder zones), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Good Luck Plant is hardy across USDA 6-10 (with winter mulch in colder zones); 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 good luck plant can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Good Luck Plant is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is good luck plant?

Good Luck Plant is rated USDA 6-10 (with winter mulch in colder zones) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can good luck plant survive winter outside?

Plant it out within USDA 6-10 (with winter mulch in colder zones) 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 good luck plant below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.