The Hoya genus, collectively known as wax plants, is made up of more than 200 species. The genus name pays tribute to Thomas Hoy, an English horticulturist in the late 18th century who tended the gardens of the Duke of Northumberland. Hoya plants are native to tropical rain forests in Malaysia, India, China and parts of Australia. Like other rain forest plants, hoya species twine around trees, absorbing moisture and nutrients from the air. Though cold temperatures limit its use in outdoor gardens, these tropical plants are common and intriguing indoor plants.
Hoya plants have succulent leaves that vary in shape, thickness and texture — some leaves are softer with more hairs than other species. The common name, wax plant, refers to the waxy leaves and flowers. Plants are woody and produce roots from the internodes of leaves. The trailing form of hoya plants is attractive outdoors and in your home or office.
Star-shaped flowers are the main attraction of hoya plants. Like leaves, the characteristics of flowers vary with each species. Hoya bilobata produces petite blooms that measure less than an inch in diameter, whereas Hoya imperialis bear flowers measuring 3 inches wide. Some species provide up to 70 tiny flowers per cluster; others provide fewer but larger flowers. Hoya plants produce fragrant flowers that are white or shades of pink, yellow, purple and red.
With proper lighting, moisture and soil, hoya plants thrive and add a tropical vibe to an indoor space. These plants prefer partial sun, but if flowers fail to form, the plant may need more direct light. Hoyas do well in a medium that is acidic and fibrous, such as peat or sphagnum moss. During summer, let the soil dry between watering and encourage dormancy after flowering by tapering off watering. Hold off on pruning spent flower spurs, which produce additional blooms. Hoya plants need protection from temperatures below 45 degrees Fahrenheit.
Hoya plants germinate from seed and root from cuttings. To duplicate your wax plant, take stem cuttings that have three or more nodes. Dip the cut end into a solution or powder of root hormone which encourages rooting. Prevent water loss from leaves by trimming leaves in half and plant in a moist medium. Hoya cuttings produce roots in about four weeks.