Wax Plant
Hoya carnosa · the Porcelain Flower
It grows as a vine draped over tree bark in the rainforests of East and Southeast Asia, an epiphyte that drinks like a desert plant. It has been a houseplant for over 200 years, it is safe for pets, and it blooms with clusters so glossy they look like porcelain.
Family
Apocynaceae
Origin
East and SE Asia
In the wild
Vine on bark
Indoors
0.6–1.2 m
Growth
Slow
With pets
Safe
Where it's from
East and Southeast Asia
A canopy epiphyte
Twines over tree trunks and rocks across China, Taiwan, Japan and south to Malaysia.
Drinks like a cactus
It runs CAM photosynthesis, opening its pores at night to save water like a desert succulent.
Outdoors: zones 10–12
Frost-free tropics only. A houseplant everywhere colder.
The porcelain flower
The wax plant blooms indoors, which most foliage plants never do. It produces tight ball-like umbels of star-shaped flowers, waxy and glossy enough to be called porcelain, each with a contrasting red or pink centre. They are fragrant, often stronger after dark, and secrete sticky nectar, which is why it is also called the honey plant.
Scented after dark
The sweet scent strengthens at night to pull in moth pollinators.
Never cut the spur
Flowers form on the same woody spur year after year. Remove it and you lose next year's blooms.
Blooms when bright
It needs at least a half-day of strong light to flower. Too little light, no flowers.
How to keep it
LightBright, indirect to part sun
Bright indirect keeps the foliage; a half-day of strong light makes it bloom. Avoid harsh midday glare.
WaterLet it dry between
Its semi-succulent leaves forgive a missed watering far better than soggy roots. Root rot is the top killer.
HumidityModerate to highTolerates average air. A pebble tray helps but is not required.
Temperature16–27°CKeep above about 10°C. No frost, no cold drafts.
SoilLoose, chunky mixIt wants air around its roots. Add orchid bark, perlite or pumice. Heavy soil rots it.
FeedingLightly in summerA dilute balanced feed in the growing season. A bloom feed can help flowering.
DifficultyEasyLow maintenance and long-lived. A classic forgiving passalong plant.
With petsSafeNon-toxic to cats and dogs per ASPCA. One of the few pet-safe flowering vines.
PropagationStem cuttingsA node with a leaf or two roots easily in water or a chunky mix. A single leaf rarely makes a plant.
RepottingEvery 2–3 yearsIt flowers better slightly pot-bound, so do not over-pot.
What the data says
What it costs
A common commodity heritage plant, with a modest collector layer in its variegated forms.
$10–25
Variegated Krimson Queen and Krimson Princess and well-grown Hindu Rope baskets run higher. The genuine collector money lives in rarer Hoya species, not in carnosa.
IUCN · Not assessed
In the wild
One of the most secure houseplants on Earth, while some of its wild cousins are not.
Hoya carnosa has not been assessed and is abundant after 200 years in cultivation. But several narrow-endemic Hoya species in the same Asian forests are assessed as Vulnerable or Endangered, pressured by forest clearing and wild collection. The plant on your shelf is safe; some of its relatives are not.
When it sulks
No flowersToo little light, too young, over-potted, or the bloom spur was cut off.
Mushy, yellowing stemsOverwatering and heavy soil leading to root rot. The top killer.
Wrinkled, shrivelled leavesUnderwatering or root damage.
Buds drop before openingMoving or rotating the plant while in bud, or sudden temperature swings.
PestsMealybugs in the leaf axils, plus scale and spider mites. Sooty mould can follow the nectar.
Varieties & company
The varieties
Plain greenCompacta (Hindu Rope)Krimson QueenKrimson PrincessExotica
Pairs with · keep apart from
Spider PlantPeperomiaChristmas CactusFernsCalathea
A new plant, every week.
The Data Drop from Sheets Works. New field guides like this one, in your inbox.
