Cold hardiness & minimum temperature

Is Guernsey Lily (Nerine sarniensis)cold hardy? Hardiness zone & min temp

Also called Scarlet Guernsey Lily, Cape Colony Lily, Jersey Lily.

More about guernsey lily

About Guernsey Lily

Nerine sarniensis · also called Scarlet Guernsey Lily, Cape Colony Lily · flowering

Nerine sarniensis is a South African bulb famed for its dazzling scarlet, salmon, or pink iridescent flowers — each petal catches light like spun glass. Produces flowers in early autumn before leaves appear. Less hardy than N. bowdenii and best grown under glass in the UK. Toxic to pets due to Amaryllidaceae alkaloids concentrated in the bulb.

Cold limit: USDA 8–11 (frost-free minimum) · RHS H2 (5–28°C (requires frost-free minimum of 5°C))

Watch for — Frost damage: Tender in most of the UK — temperatures below freezing will damage or kill the bulbs. Keep in a frost-free greenhouse or conservatory from October to April.

What guernsey lily's hardiness rating actually means

Guernsey 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 (frost-free minimum) — 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. Guernsey Lily shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for guernsey 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 guernsey lily go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8–11 (frost-free minimum) 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 guernsey 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 guernsey lily

Guernsey 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.

Guernsey Lily hardiness — frequently asked questions

Is guernsey lily cold hardy?

Guernsey 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 (frost-free minimum) (and sheltered UK gardens) guernsey 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 guernsey lily can survive?

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

What hardiness zone is guernsey lily?

Guernsey Lily is rated USDA 8–11 (frost-free minimum) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can guernsey lily survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8–11 (frost-free minimum) 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 guernsey 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.