Cold hardiness & minimum temperature

Is White Rain Lily (Zephyranthes candida)cold hardy? Hardiness zone & min temp

Also called White rain lily, Peruvian swamp lily, Autumn zephyr lily, Fairy lily.

More about white rain lily

About White Rain Lily

Zephyranthes candida · also called White rain lily, Peruvian swamp lily · flowering

Zephyranthes candida is a small bulbous perennial from Argentina and Uruguay, producing a succession of elegant white, crocus-like flowers with golden stamens from late summer through autumn, typically triggered to bloom by rainfall after a dry spell. It naturalises freely in moist, well-drained soil in warm climates and is well suited to growing in containers in cooler regions. Consistent moisture combined with periodic dry spells that mimic its natural rainfall rhythm produces the most prolific flowering. Zephyranthes candida contains Amaryllidaceae alkaloids including lycorine and should be treated as mildly toxic to cats and dogs.

Cold limit: USDA 7-10 · RHS H3 (-5°C to 35°C)

Watch for — Bulb rot in cold, waterlogged winter soil: In USDA zone 7 or UK gardens in cold winters, bulbs left in wet, frozen soil will rot; lift and store in barely moist vermiculite at 5–10°C over winter, or grow in containers that can be brought under cover.

What white rain lily's hardiness rating actually means

White Rain Lily is half-hardy (RHS H3). 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 H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 7-10 — 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 −5 to 1 °C — a light, short frost only. White Rain Lily shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for white rain lily as it gets too cold:

Down to roughly about −5 to 1 °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 white rain lily go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 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 white rain lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline white rain lily

White 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.

White Rain Lily hardiness — frequently asked questions

Is white rain lily cold hardy?

White Rain Lily is half-hardy (RHS H3). 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 7-10 (and sheltered UK gardens) white 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 white rain lily can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. White Rain Lily shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is white rain lily?

White Rain Lily is rated USDA 7-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can white rain lily survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 7-10 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 white 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.