Cold hardiness & minimum temperature

Is Ly's Wax Plant (Hoya lyi)cold hardy? Hardiness zone & min temp

Also called Ly's wax plant, Ly's hoya.

More about ly's wax plant

About Ly's Wax Plant

Hoya lyi · also called Ly's wax plant, Ly's hoya · tropical

Hoya lyi is a lithophytic scrambling subshrub native to southern China (Guizhou, Sichuan, Yunnan), Laos, and Vietnam, where it grows tightly against limestone rocks in deep shade — making it one of the most cold-tolerant and shade-tolerant hoyas in cultivation. Its daytime-opening, sweetly fragrant flowers range from pure white to pale pink with pink or purple centres, and the most important care note is that it can tolerate brief light frosts, making it suitable for cool conservatories in the UK. The ASPCA lists the Hoya genus as non-toxic to cats and dogs.

Cold limit: USDA 9-12 · RHS H2 (5–28°C)

Watch for — Failure to flower without cool rest: Like many cool-growing hoyas, H. lyi benefits from a cooler, drier winter rest (around 10–15°C) to trigger flowering the following spring.

What ly's wax plant's hardiness rating actually means

Ly's Wax 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 9-12 — 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. Ly's Wax Plant shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for ly's wax 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 ly's wax plant go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-12 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 ly's wax 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 ly's wax plant

Ly's Wax 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.

Ly's Wax Plant hardiness — frequently asked questions

Is ly's wax plant cold hardy?

Ly's Wax 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 9-12 (and sheltered UK gardens) ly's wax 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 ly's wax plant can survive?

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

What hardiness zone is ly's wax plant?

Ly's Wax Plant is rated USDA 9-12 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can ly's wax plant survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-12 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 ly's wax 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.