Hoyas: Great Houseplants

If you’re searching for the perfect houseplant, look no further. I have one word for you: Hoya.

There are more than 200 Hoya species, mostly vining, tropical plants native to southern Asia, Polynesia, and Australia. Some come from subtropical zones (the foothills of the Himalayas, the northern coast of Australia), and these can take temps as cool as 45°F. Most hoyas are epiphytes, so they grow best in a lightweight, coarse growing medium that allows good contact between the plant’s roots and the surrounding air. (You can make your own. Combine two parts soilless mix with one part fine-grained bark mix for a custom blend perfect for most epiphytes.)

The vast majority of hoyas have succulent or semi-succulent leaf tissue, which works out nicely for us indoor growers. Drought-tolerant plants make low-maintenance houseplants. But don’t try to pin me down on general leaf size, color, or texture. It’s just no use. The foliage of some miniature species is half an inch in diameter, while larger vines can bear leaves 15 inches long. Leaves can be solid dark or light green, or they can be green with silver, white, pink, or red variegation. Finally, the leaves can be glossy, fuzzy, heavily veined, or none of the above.

Here’s a constant to cling to: hoya flowers will always have a five-part corona on top of a five-part corolla. Of course, they may still look as different from one another as a dachshund does from a golden retriever. Some species’ flowers are fringed; others, smooth and waxy. Some are a quarter-inch in diameter; others, two inches across. Some are wildly reflexed, others are flat. Regardless, the flowers originate from peduncles, or bloom spurs. Most hoyas rebloom on existing peduncles, so leave them in place after the flowers have dropped. Peduncles grow with each round of bloom, which means those on older plants can be several inches long.

Hoyas belong to the Asclepiadaceae, or milkweed family. Like the seeds of other milkweeds, hoya seeds ripen in pods and float on silk. They aren’t viable for long and pods rarely form indoors, so most hoyas are propagated from cuttings. Dip cuttings in rooting hormone and stick them in a lightweight mix; they’ll root within six weeks. Hoyas grow best in average household temperatures, a soilless mix, and bright indirect light. Many can take direct sun, but their foliage may become bleached. In winter, let your hoyas dry out between waterings and don’t feed them. During the warmer growing season, water them once a week or so and apply a balanced fertilizer every other week. Hoyas should never be allowed to sit in water or persistently damp soil. Remember, these are epiphytic semi-succulents—wet roots can be deadly.

HOYAS TO GROW

Your first hoya will probably be H. carnosa, the classic wax plant. I’ve never been sure if wax describes the smooth, shiny leaf surface or the perfectly formed, dark pink on light pink flowers, but it hardly matters. Give it a bright windowsill, some benign neglect, and you’ll be rewarded with climbing vines and fragrant blooms. That ought to whet your appetite for diverse members of the genus. Then my top 10 list may come in handy.

Hoya caudata raises the age-old question: “Which is more beautiful, the foliage or the flowers?” Its foliage is ovate, to four inches long. The leaf surface is rough, with large blotches of silver. Red undertones appear in high light. Its flowers hang in flat umbels, giving them a distinctive pendant shape. The white blooms have cherry red corollas and prominent stamens.

Hoya serpens has an undeserved reputation for being difficult to bloom. Keep this miniature near a window where nighttime temperatures get into the 50s and it blooms reliably. Pale green flowers, with pink centers and fringed in white, outsize the half-inch, white-flecked dark green leaves.

Some people call H. kerrii the sweetheart hoya because of its four-inch heart-shaped leaves, but this muscular plant deserves a more imposing moniker. King of hearts, perhaps? It grows best on a tipi or tuteur. Train the vines while they are young; as they get older they become inflexible and ooze milky sap if they break. The flowers of H. kerrii are white with burgundy coronas.

Hoya retusa is a weird looking plant. (I like weird.) Its two-inch-long, very narrow leaves end in indented square tips. They appear in pairs along the vining stem, and pink-centered white flowers emerge singly or doubly (that’s right, no umbels!) from leaf nodes. This is a small hoya, well suited to a windowsill.

I’d grow H. vitellina even if it never flowered. Its gently wavy, five-by-three-inch medium green leaves are boldly edged in purple. The variegation becomes more pronounced in higher light. Its gently fragrant flowers are white with pale pink corollas.

You know when H. lacunosa is in bloom the minute you walk through the door—it’s a highly fragrant plant! Its leaves are small, lanceolate, and dark green. The plant trails, but doesn’t put out long questing vines. It makes a nice compact hanging basket in limited growing space. Hoya lacunosa blooms continuously from October through June, with new cream-colored flowers forming on umbels before the old ones have fallen off.

Hoya polyneura gets its nickname, the fish-tail hoya, from its leaves’ unique venation and rhomboidal shape. Closely spaced dark veins mark the three-inch leaves, and a dark green border runs around their margins. Grow it in a hanging basket; its flowers are held on umbels that form beneath the leaves, making the plant best viewed from below. This hoya doesn’t rebloom on old peduncles but forms new umbels at the end of each stem. Flowers are white with luscious ruby red coronas.

Hoya lobbii is both unusual and reliable—just what you’re looking for in a houseplant. Maroon coronas crown dusky pink corollas. Flowers last for up to two weeks—that’s long for hoya blooms. Small specimens have an upright growth habit, but with age the self-branching stems start to trail. This species’s long narrow leaves are less succulent than most hoyas’.

Hoya shepherdii looks spectacular in bloom, owing to its high umbel-to-leaf ratio. Flowers are pale pink with rose coronas and a pleasant scent. Long internodes run between the five-inch-long, half-inch-wide leaves. This is a tough plant. Knocked over while I was on vacation in July (each cat blamed the other), it lay on a windowsill with its roots exposed for a week or so, but it bloomed in September. You can’t keep a good hoya down.

Hoya curtisii has spade-shaped leaves (like the card suit, not the digging tool), a half inch in diameter and strongly flecked with silver and red. This bushy plant forms a thick mat of foliage. The white petals point 180 degrees away from the dark pink coronas. Individual flowers are almost as large as the leaves.

Once you’ve been bit by the hoya bug there’s no going back. Newsletters, international symposia, and support groups are in your future. Perhaps even a tattoo. (No wait—that’s me.) Considering these plants’ low maintenance, fragrant flowers, and gorgeous foliage, go ahead and give in. It’s a happy obsession.