Cold hardiness & minimum temperature

Is Moss-Leaf Wax Plant (Hoya hypnophylla)cold hardy? Hardiness zone & min temp

Also called Moss-leaf wax plant, Moss-leaf hoya.

More about moss-leaf wax plant

About Moss-Leaf Wax Plant

Hoya hypnophylla · also called Moss-leaf wax plant, Moss-leaf hoya · tropical

Hoya hypnophylla is a distinctive, collector-grade epiphytic wax plant from Southeast Asia, named for its unusual, somewhat moss-textured or softly hairy leaves (hypno referencing the moss genus Hypnum). It produces clusters of fragrant, star-shaped wax flowers and thrives with the standard Hoya regime of bright indirect light, an airy bark-based medium, and restrained watering. Because the textured foliage can trap moisture, it is especially important to avoid overhead watering and ensure good airflow. The ASPCA lists the Hoya genus as non-toxic to cats and dogs.

Cold limit: USDA 11-12 (indoor in most climates) · RHS H1b (18–28 °C)

What moss-leaf wax plant's hardiness rating actually means

Moss-Leaf Wax Plant is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 11-12 (indoor in most 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 10 °C (sustained cold below this is damaging). Moss-Leaf Wax Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for moss-leaf wax plant as it gets too cold:

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can moss-leaf wax plant go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 moss-leaf wax plant can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Moss-Leaf Wax Plant hardiness — frequently asked questions

Is moss-leaf wax plant cold hardy?

Moss-Leaf Wax Plant is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Moss-Leaf Wax Plant can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature moss-leaf wax plant can survive?

What hardiness zone is moss-leaf wax plant?

Moss-Leaf Wax Plant is rated USDA 11-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can moss-leaf wax plant survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to moss-leaf wax plant below its minimum temperature?

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.