Wax Plant Poetic: Why the Hoya Is One Part Houseplant, One Part Hanging Heirloom

Photos by Ryan Benoit

Here’s the thing about our houseplants: We mostly keep them outside. We don’t have a lot of room indoors, so we’ll hang certain flora — ones you might associate with offices and brightly lit bathrooms — from the north-facing eave outside our one-story home. It also helps that temperatures here don’t get that far below 50 in the winter.

One of these plants is our Hoya carnosa, commonly known as hoya, porcelain flower or wax plant. Known for its curving vines stacked with waxy leaves (hence the name), this species of hoya is native to Southeast Asia and Australia. When it flowers it sends out star-shaped blooms in startling spherical and hemispherical clusters, flowers that look and feel like they’ve been sculpted from marzipan.

Hoya carnosa

Wax plants make great houseplants. Make sure to find a location with bright indirect light. Above, Ryan’s mother Denise shows off her Hoya carnosa’s latest blooms.

Hoya carnosa

Hoya carnosa

Check out these buds. Flowers will flare from the same spurs over and over again, so it’s important not to cut the spurs after the blooms fade.

Hoya carnosa

We witnessed all the flowers on this “flare” fully open in the course of a day.

Hoya carnosa

On closer examination, the flowers are quite textured and multi-layered. Above the fuzzy star-shaped petals are slick, star-shaped coronas.

Despite their fleshy look, the flowers are actually covered in tiny hairs. (Just like…humans?) Across the Hoya genus, each umbellate flower cluster emerges from a single spur — that is, a peduncle that grows from the axil of the leaves and stem. The spurs bear repeat blooms, and should not be removed. The buds are oddly flat-topped, like textured candies, and each flower typically includes not just one star figure but two: the petals and the corona, which together give these miniature blossoms an intense depth and dimensionality. Many hoya blossoms are outrageously fragrant; ours only smelled mildly of chocolate.

We have the ‘Krinkle 8’ cultivar, so named for its dimpled foliage. We picked it up about a month ago, when it was still in bloom, but Ryan has known about the magic of the hoya for a while; his parents have been growing them for decades, including a variegated one that was acquired at a “plant party” in the 1973. (“A van would pull up and bring in dozens of plants for a group of friends at the house, sort of like a Tupperware or Avon party,” said Ryan’s mom Denise.) The longevity theme reemerged when we posted a shot to Instagram. “My grandmother had the same plant her whole life,” one commenter, NYCBone, said.

Hoya carnosa 'Krinkle 8'

We brought home a Hoya carnosa ‘Krinkle 8.’

Hoya carnosa 'Krinkle 8'

‘Krinkle 8’ refers to the eight dimples on each leaf.

Hoya carnosa 'Krinkle 8'

The leaf and stem structure of this cultivar make for a beautiful hanging plant.

The plants of Hoya genus (named after English botanist Thomas Hoy) are evergreen perennials, and often grow as epiphytes, like tillandsias and epiphyllums, meaning they rely on trees and moss poles and terrestrial features like rocks for structural support. Because they’ve evolved to thrive in these tight spots, these plants actually prefer to be root-bound. Another thing in common with cactus orchids!

Care tips for your hoya:

– Hardiness varies by species. If growing outdoors, some varieties of hoya are hardy in USDA Zones 8 through 11; others (like our H. carnosa) will only abide zones 10 through 11.

– Many people grow hoyas as houseplants. If indoors, cooler temps are A-OK during the winter but make sure they don’t drop below 50. The plants enjoy the warm temperatures of the spring and summer growing season.

– Humidity in your hoya habitat should be at least 40 percent. This can be achieved through regular misting with a spray bottle.

– Put it in a spot with bright indirect light, like a north-facing window.

– Evenly moist, well-drained soil is preferred. Plant Care Today specifically recommends “African violet soil with some added perlite.”

– Again, do not remove spurs after the blooms have faded. That’s where the next round of flowers will blossom. Allow faded flowers to fall off naturally.

– Apply a balanced fertilizer only during active growing season, i.e. spring and summer.

– Pot-bound plants will flower more vigorously.

– Keep soil moist in spring and summer, but allow it to dry in the winter — water just enough so the leaves won’t shrivel.

– Hoyas are most commonly propagated by cuttings. Vermont Hoyas shares its technique here.

– In general, don’t helicopter-garden this baby. It favors a bit of benign neglect. And definitely don’t move the plant while it’s blooming.

Hoya carnosa 'Krinkle 8'

Keep the plant root-bound for years, eventually stepping up pot size by 1 to 2 inches. Make sure to always plant in lose and well-draining soil.

Hoya carnosa 'Krinkle 8'

A spent spur. A flower will grow again out of this same spur next season. Do not cut away these old dormant spurs.

Hoya carnosa 'Krinkle 8'

We placed our hoya outside beneath an eave, our Zone 10B outdoor home for a houseplant. If growing indoors, hanging next to a north-facing window should ensure adequate light.

Hoya carnosa 'Krinkle 8'

Hoyas are epiphytic vines native to Southeast Asia and Australia.

Hoya carnosa 'Krinkle 8'

Hoya carnosa

We almost forgot to mention that we have a second Hoya carnosa! It’s rooted in a pot at the base of our guava tree and vertical shade garden.

Hoya carnosa

Unlike the ‘Krinkle 8,’ its leaves are flat and splotchy.

Hoya carnosa

Hoyas are climbers. This one is working its way up the guava tree.

Hoya carnosa

We’ve yet to see a flower over the past year since we’ve had it. This might be due to our transplanting it into a pot that’s too big.

If you’re ISO a hoya to call your own, they aren’t terribly hard to find. The Plant Attraction and EBay are two online sources. Another thing we do when we’re looking for a local supplier is to search for the name of the desired plant on Yelp — an approach that has yielded all sorts of discoveries.

Wax on.

—TH