Cold hardiness & minimum temperature

Is Pygmy Tongue Plant (Glottiphyllum pygmaeum)cold hardy? Hardiness zone & min temp

Also called Pygmy Tongue Leaf, Dwarf Tongue Plant.

More about pygmy tongue plant

About Pygmy Tongue Plant

Glottiphyllum pygmaeum · also called Pygmy Tongue Leaf, Dwarf Tongue Plant · houseplant

Glottiphyllum pygmaeum is a miniature South African succulent with very short, densely packed, fleshy green leaves and bright yellow autumn flowers. One of the smallest in the genus, it is ideal for windowsill collections. It requires maximum sun and almost no water in winter. Not ASPCA-confirmed non-toxic; treat cautiously around pets.

Cold limit: USDA 10-11 · RHS H2 (10-30°C)

Watch for — No autumn flowers: Requires a warm, bright summer and then a cooler, drier winter to stimulate flowering.

What pygmy tongue plant's hardiness rating actually means

Pygmy Tongue 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 10-11 — 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. Pygmy Tongue Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for pygmy tongue 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 pygmy tongue plant go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-11 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 pygmy tongue 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 pygmy tongue plant

Pygmy Tongue 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.

Pygmy Tongue Plant hardiness — frequently asked questions

Is pygmy tongue plant cold hardy?

Pygmy Tongue 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 10-11 (and sheltered UK gardens) pygmy tongue 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 pygmy tongue plant can survive?

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

What hardiness zone is pygmy tongue plant?

Pygmy Tongue Plant is rated USDA 10-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can pygmy tongue plant survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 10-11 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 pygmy tongue 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.