Cold hardiness & minimum temperature

Is Forest Lily Amaryllis (Hippeastrum aulicum)cold hardy? Hardiness zone & min temp

Also called Court Amaryllis, Forest Hippeastrum, Red Forest Amaryllis.

More about forest lily amaryllis

About Forest Lily Amaryllis

Hippeastrum aulicum · also called Court Amaryllis, Forest Hippeastrum · flowering

Hippeastrum aulicum is a forest-dwelling Brazilian species producing deep crimson-red flowers with a greenish throat in winter or early spring. One of the species central to early amaryllis hybridisation. Grows in dappled forest light and tolerates lower light than most Hippeastrum. Toxic to pets due to lycorine and alkaloids throughout the plant.

Cold limit: USDA 9–11 (outdoor); indoor in temperate climates · RHS H2 (15–27°C (dormancy at 12–15°C))

What forest lily amaryllis's hardiness rating actually means

Forest Lily Amaryllis 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 (outdoor); indoor in temperate climates — 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. Forest Lily Amaryllis shrugs off cold nights but a real, sustained freeze will kill it.

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

It can live outside year-round only in the mildest, most sheltered part of USDA 9–11 (outdoor); indoor in temperate climates 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 forest lily amaryllis 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 forest lily amaryllis

Forest Lily Amaryllis 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.

Forest Lily Amaryllis hardiness — frequently asked questions

Is forest lily amaryllis cold hardy?

Forest Lily Amaryllis 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 (outdoor); indoor in temperate climates (and sheltered UK gardens) forest lily amaryllis can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature forest lily amaryllis can survive?

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

What hardiness zone is forest lily amaryllis?

Forest Lily Amaryllis is rated USDA 9–11 (outdoor); indoor in temperate climates and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can forest lily amaryllis survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9–11 (outdoor); indoor in temperate climates 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 forest lily amaryllis 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.