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How to Grow Wax Plant — Hoya

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Hoya is a shrubby or climbing tropical plant with leathery green leaves that appear in pairs along a flexible stem. Clusters of fragrant, star-shaped flowers are borne above pairs of leaves. Vines usually reach 3 feet (1m) long.

Both the leaves and flowers of Hoya have a waxy appearance. The glazed look of the star-shaped white blooms gives the plant its common names, porcelain flower, and wax plant.

Hoya has been a houseplant favorite for many years. It is typically trained on a trellis or up strings. Hoya can easily be trained to a wire hoop, topiary, or grown in a hanging basket. Hoya produces clusters of small white, honey-scented flowers that look like porcelain. The flowers dangle from the long vining stem.

Hoya is grown as a houseplant in all but tropical regions. Where winter temperatures never drop below 50°F (10°C), wax plant can be grown outdoors.

Hoya is a genus of more than 200 species of evergreen perennials and climbers. Hoya carnosa is most commonly grown as a houseplant. The Hoya genus is native to stream margins and rainforests in tropical Asia, Australia, and the Pacific Islands.

Get to know Hoya

  • Plant type: Tropical perennial
  • Growing Zones and range: Zones 12-15
  • Hardiness: Tender; best not below 50°F (10°C)
  • Optimal growing temperature: day 70°F (21°C), night 55° to 60°F (13°-16°C)
  • Height and width: 24 to 36 inches (60-90cm) tall and wide as a housplant; in tropical regions 15 to 25 feet (5-8m) tall depending on the variety
  • Foliage: Long trailing stems with waxy, leathery succulent silvery green leaves to 3 inches (7.5cm) long; leaf shapes and colors vary
  • Flowers: Clusters of small, star-shaped; ½-inch across white flowers with reddish-purple centers; flowers have a honeylike scent; flowers dangle from stems. Flowers are produced repeatedly on leafless spurs that grow from the main stem.
  • Bloom time: Summer
  • Uses: Grown as a houseplant in most regions; best on a trellis or in a hanging basket; can be grown in outdoor container plant in warm-winter regions
  • Common name: Wax plant, porcelain flower
  • Botanical name: Hoya
  • Family: Asclepiadaceae
  • Origin: Asia, Australia, Pacific Islands
Hoya carnosa variegata 'Krimson Queen'
Hoya carnosa variegata ‘Krimson Queen’

Where to plant Hoya

  • Light indoors: Grow Hoya in strong reflected light, not direct sunlight.
  • Light outdoors: Full sun with some shade depending on the variety; direct morning sun encourages flowering; avoid mid-day sun.
  • Soil indoors: Plant Hoya in indoor potting soil. Grow Hoya in a peat moss-based mix in a pot or in a hanging basket lined with sphagnum moss.
  • Soil outdoors: Humus-rich, well-drained soil.

How to water and feed Hoya

  • Allow the soil surface to dry out between waterings; in winter water slightly less; higher humidity encourages flowering. Hoya needs slightly higher than average humidity; mist plants daily.
  • From spring through fall, let the soil dry between waterings. In winter reduce water drastically, just enough to prevent shriveling. Do not use cold water.
  • Fertilize three times in summer with a 10-30-10 liquid fertilizer; do not fertilize in winter during the rest period.

Hoya care

  • Provide potted plants with a trellis or wire hoop; wind the stems counterclockwise around the support
  • Mature plants prefer to be potbound. Hoya blooms best with potbound. Repot young plants each year after the rest period.
  • Hoya must be 3 feet (90cm) long to bloom, so avoid pruning—pruning may remove the stubby flowering spurs
  • Carefully remove faded blooms leaving woody spur extending from leaf axil intact; from these spurs, new blooms will emerge.
  • Let plant rest from fall through winter; it becomes semi-dormant. Set in a cool spot, 50°F (10°C); give just enough water to keep soil from drying out; withhold fertilizer.

Growing Hoya as a houseplant

  • Hoya must have direct light, average room temperature, and low humidity. Does best in average warm conditions; avoid cold drafts.
  • the soil should be kept moderately dry; soggy soil can cause root rot.
  • Fertilizer should be applied occasionally during sprig and summer; excess fertilizer can cause the flower buds to drop.

Hoya pests and diseases

  • Hoya can be attacked by aphids, mealybugs, mites, root rot, and scale.

Hoya propagation

  • Propagate by layering or stem cuttings.
  • Take stem cuttings in spring of the previous year’s growth.
  • Hoya can be propagated by layering.

Hoya varieties to grow

  • Hoya australis. Grows 12 to 20 feet in tropical regions; has greenish-white flowers with red bases and white crowns.
  • H. bella, miniature wax plant, grow to 1 foot (30cm) high and has leaves that are dull green, oval to lance-shaped; flowers are ½ inch across; best grown in a basket; white flowers with crimson centers.
  • H. carnosa, wax plant, honey plant. Ovate, rigid, fleshy leaves to 3 inches long, smooth dark green; bears dense umbels of pinkish-white flowers with red crowns; the leaves of one cultivar twist and curl, and thus the plant is called Hindu rope plant. Hoya carnosa is commonly grown; cultivars below:
  • ‘Variegata’ has cream-edged leaves.
  • ‘Exotica’ has leaves with yellow centers and green margins.
  • ‘Krimson Princess’ has reddish young leaves.
  • ‘Krimson Queen’ has reddish-green leaves with ivory margins.
  • ‘Tricolor’ has leaves that are copper and salmon-rose when young and green with ivory margins when mature.
  • H. imperialis. Strong-growing, twining climbet has purple blooms with ivory crowns.
  • H. multiflora has pale yellow flowers

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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