Cold hardiness & minimum temperature

Is Cettos Achimenes (Achimenes cettoana)cold hardy? Hardiness zone & min temp

Also called Cettos Achimenes.

More about cettos achimenes

About Cettos Achimenes

Achimenes cettoana · also called Cettos Achimenes · houseplant

Achimenes cettoana is among the most compact species in the genus, producing small lilac-to-mauve funnel-shaped flowers on short stems throughout summer and into autumn. Originating from Mexico, it suits small pots and windowsill culture. Like all Achimenes, it grows from scaly rhizomes and demands a dry winter rest before resuming growth in spring.

Cold limit: USDA 10–12 · RHS H1b (18–24°C active growth; 13–16°C winter storage)

Watch for — Failure to re-sprout in spring: Rhizomes kept too cold (below 10°C) or too wet during dormancy may rot or fail to break dormancy. Store in barely damp (not wet) perlite at 13–16°C and check for firmness before planting.

What cettos achimenes's hardiness rating actually means

Cettos Achimenes 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 H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 10–12 — 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 °C (sustained cold below this is damaging). Cettos Achimenes has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for cettos achimenes as it gets too cold:

Below about about 10 °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 cettos achimenes go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °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 cettos achimenes can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Cettos Achimenes hardiness — frequently asked questions

Is cettos achimenes cold hardy?

Cettos Achimenes 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. Cettos Achimenes can only live outside year-round in genuinely frost-free climates (roughly USDA 10–12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature cettos achimenes can survive?

What hardiness zone is cettos achimenes?

Cettos Achimenes is rated USDA 10–12 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can cettos achimenes survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °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 cettos achimenes below its minimum temperature?

Below about about 10 °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.