Cold hardiness & minimum temperature

Is Inch Plant (Tradescantia fluminensis)cold hardy? Hardiness zone & min temp

Also called Inch plant, Small-leaf spiderwort, Wandering trad, Wandering Willie, River spiderwort, White-flowered spiderwort.

More about inch plant

About Inch Plant

Tradescantia fluminensis · also called Inch plant, Small-leaf spiderwort · houseplant

The inch plant (Tradescantia fluminensis) is a fast-growing trailing houseplant with small fleshy leaves, prized for cascading stems in pots and hanging baskets. Give it bright indirect light, water when the top half of the soil dries, and pinch to keep it bushy. The ASPCA lists it as toxic to cats, dogs and horses (dermatitis), so it is mildly toxic.

Cold limit: USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) (16-27C)

What inch plant's hardiness rating actually means

Inch Plant is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) — 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 1 to 5 °C — tolerates cold but no real frost. Inch Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for inch plant as it gets too cold:

Down to roughly about 1 to 5 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can inch plant go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 inch plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline inch plant

Inch Plant is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Inch Plant hardiness — frequently asked questions

Is inch plant cold hardy?

Inch Plant is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) (and sheltered UK gardens) inch plant can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature inch plant can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Inch Plant shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is inch plant?

Inch Plant is rated USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can inch plant survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (grown as a houseplant in cooler zones; frost-tender) or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect inch plant from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.