Cold hardiness & minimum temperature

Is Roth's Air Plant (Tillandsia rothii)cold hardy? Hardiness zone & min temp

Also called Roth's Air Plant.

More about roth's air plant

About Roth's Air Plant

Tillandsia rothii · also called Roth's Air Plant · tropical

Tillandsia rothii is a large, striking epiphytic air plant native to the west coast of Mexico (Jalisco and Colima states), where it grows in dry tropical forest at low elevations. Its gracefully recurving, lime-green to silver leaves form a full, arching rosette reminiscent of T. xerographica, and at bloom time the entire plant flushes deep crimson, producing a compound inflorescence in shades of cherry, moss green, and chartreuse. Providing bright light is essential to trigger this spectacular colour change. It is listed as non-toxic to cats and dogs by the ASPCA.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (10–30°C)

Watch for — Basal rot: Water pooling in the wide rosette centre, especially in cooler winter conditions, causes the inner leaves to blacken; tilt the plant after each watering to drain and position in a room with good ventilation.

What roth's air plant's hardiness rating actually means

Roth's Air Plant 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 (indoor in most climates) — 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). Roth's Air Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for roth's air plant 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 roth's air plant 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 roth's air plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Roth's Air Plant hardiness — frequently asked questions

Is roth's air plant cold hardy?

Roth's Air Plant 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. Roth's Air Plant can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature roth's air plant can survive?

What hardiness zone is roth's air plant?

Roth's Air Plant is rated USDA 10-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can roth's air plant 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 roth's air plant 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.