Hoyas (Wax Plants)

How to choose a hoya

Hoya carnosa is the old favourite and the easiest place to start. The Pink Hoya carnosa has plain deep green leaves, while Hoya carnosa Krimson Queen has leaves edged in cream and pink, so it earns its place even when it is not in flower. Variegated hoyas grow more slowly and need a little more light than green ones.

The Silver Pink Hoya is a form of Hoya pubicalyx, a vigorous species with long, narrow leaves that suits a tall support or a large basket. The Red Hoya is Hoya coronaria, a tropical species with thick, felted leaves that wants steady warmth, and the Pink Hoya globulosa comes from cooler mountain forest and dislikes long hot, dry spells.

Where hoyas grow

Indoors, give a hoya the brightest spot you have out of direct midday sun: near an east facing window, or a metre back from a northern one. Too little light is the usual reason a healthy plant never flowers. Outdoors, hoyas grow all year on a covered patio or under a tree in tropical and subtropical gardens. In warm temperate areas keep them under cover and out of cold wind, and bring them inside wherever frost occurs, because frost kills them.

They sit well beside other indoor plants and indoor flowering plants, and outdoors in warm districts they can be grown with other climbers on a shaded trellis.

Planting and spacing

Hoyas have small root systems and flower more freely when slightly pot bound, so move up only one pot size at a time, in spring or early summer. Use a coarse, open mix: a quality potting mix opened up with orchid bark and perlite drains fast and lets air reach the roots. Give a climber a hoop, a small trellis or a wire to twine around, or let the stems trail from a hanging basket. One plant per pot is enough.

Care basics

Let the mix dry out between waterings, then water thoroughly and let the pot drain. The fleshy leaves store water, and far more hoyas are lost to wet feet than to drought. Water less in winter, when growth slows. Feed lightly from spring to autumn with a liquid fertiliser at half strength.

Never cut off the old flower spurs. A hoya flowers again from the same short spur year after year, so removing it removes next season's flowers. The long leafless tendrils a plant sends out are also normal: they are looking for something to climb, and leaves follow. Hoyas have a milky sap that can irritate skin, so wear gloves when you prune or take cuttings and wash your hands afterwards.

Common questions

Why is my hoya not flowering?

Usually it needs more light, or it is still young. Many hoyas take two or three years to settle before they flower. Keep the plant in bright indirect light, leave it a little pot bound and never remove the old flower spurs.

How often should I water a hoya?

Only when the mix has dried out. In a warm room over summer that may be weekly; in winter it can be every two or three weeks.

Can hoyas grow outside in Australia?

Yes, in a sheltered, frost free position with bright shade. They grow outdoors all year in the tropics and subtropics, and under cover in warm temperate areas. In cold districts treat them as indoor plants.

Do hoyas need a trellis?

Not always. The twining kinds will climb a hoop or trellis, or trail from a basket if you prefer.