Cold hardiness & minimum temperature

Is Impatiens (Impatiens walleriana)cold hardy? Hardiness zone & min temp

Also called busy lizzie, patience plant.

About Impatiens

Impatiens walleriana · also called busy lizzie, patience plant · flowering

Impatiens are tender perennials grown as annuals for masses of flat pastel flowers in shade. New Guinea types are more sun-tolerant. Downy mildew has hit some areas; choose resistant cultivars. Pet-safe.

Impatiens walleriana (busy Lizzy) is a tender East African species grown as a shade annual (perennial only in USDA 10–11), uniquely able to produce bright color in deep shade where few flowers perform.

Highly susceptible to impatiens downy mildew (Plasmopara obducens — white fuzzy growth on leaf undersides, leaf drop, collapse); choose resistant series such as Beacon or Imara XDR where the pathogen is established.

Cold limit: USDA 10-11 (annual elsewhere) · RHS H1c (15-24°C)

Sources: ipm.missouri.edu, extension.umd.edu, umass.edu

What impatiens's hardiness rating actually means

Impatiens is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-11 (annual elsewhere) — 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 5 °C (and never frost). Impatiens has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for impatiens as it gets too cold:

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can impatiens go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 impatiens can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Impatiens hardiness — frequently asked questions

Is impatiens cold hardy?

Impatiens is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Impatiens can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (annual elsewhere)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature impatiens can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Impatiens has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is impatiens?

Impatiens is rated USDA 10-11 (annual elsewhere) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can impatiens survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to impatiens below its minimum temperature?

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.