Cold hardiness & minimum temperature

Is Large-flowered Rain Lily (Zephyranthes grandiflora)cold hardy? Hardiness zone & min temp

Also called Pink Rain Lily, Pink Zephyr Lily, Rosy Rain Lily.

More about large-flowered rain lily

About Large-flowered Rain Lily

Zephyranthes grandiflora · also called Pink Rain Lily, Pink Zephyr Lily · flowering

Large-flowered Rain Lily is a Mexican and Central American bulbous perennial bearing large, bright rose-pink funnel-shaped flowers on short stems after rainfall or irrigation in summer and early autumn. It is one of the most spectacular rain lilies for containers and warm gardens. Toxic to pets — contains Amaryllidaceae alkaloids; keep pets away from all parts.

Cold limit: USDA 8-11 · RHS H2 (10-32°C)

Watch for — Bulb rot: Overwatering between bloom cycles or continuously wet winter soil causes rot. Ensure good drainage and withhold water in winter.

What large-flowered rain lily's hardiness rating actually means

Large-flowered Rain Lily 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 8-11 — 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. Large-flowered Rain Lily shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for large-flowered rain lily 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 large-flowered rain lily go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 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 large-flowered rain lily 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 large-flowered rain lily

Large-flowered Rain Lily 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.

Large-flowered Rain Lily hardiness — frequently asked questions

Is large-flowered rain lily cold hardy?

Large-flowered Rain Lily 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 8-11 (and sheltered UK gardens) large-flowered rain lily can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature large-flowered rain lily can survive?

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

What hardiness zone is large-flowered rain lily?

Large-flowered Rain Lily is rated USDA 8-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can large-flowered rain lily survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-11 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 large-flowered rain lily 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.