The hoya carnosa is a woody evergreen vine that produces large masses of pink or white flowers. The long-lasting flowers, which have a pleasing scent, are capped with tiny, five-pointed stars. The foliage is green or variegated. Nicknamed the wax plant for its thick, waxy leaves, the hoya carnosa is a slow-growing plant and sensitive to cold temperatures. For those reasons, the hoya carnosa is often grown indoors as a houseplant.
Light and Temperature
Hoya carnosa grows best in part sun. Morning sunlight with afternoon shade is ideal. This plant can take a long time to flower--up to eight years--so make sure it receives at least half a day of sunlight to promote blooming. Too much direct sunlight, however, can scorch the leaves. Indoor plants should be placed in a west or south-facing window, according to Debra Brown, a horticulturist at the University of Minnesota. This succulent also needs warm temperatures. If the vine is exposed to temperatures below 45 degrees F, it could die.
The wax plant will actually grow in a wide variety of soils, from sandy to clay and acidic to alkaline. It will not tolerate salty soil, however. The vine does best in rich, loamy soil that drains well. Most high-quality potting soils are fine for this plant, as long as the container has drainage holes. If planting hoya carnosa outside, mix a little leaf mold into the soil, along with some sand to help the soil drain.
Water hoya carnosa when the soil is quite dry. The wax plant is a succuluent--the leaves hold water--and does not have to be watered very often. When you do water it, make sure the water is at room temperature. If the vine is potted, empty the drainage tray immediately after the water has finished trickling out of the bottom of the pot. Standing water can cause root rot.
Because wax plants are slow-growing vines, they really don't need regular feedings. You can give your plant a dose of fertilizer when you do see new growth appear. This will probably be in the spring. Follow up with another dose in mid-summer. Use a fertilizer that is formulated for succulents, and one that is water-soluble.
Do not prune this plant. Let the long vines develop. Although they may seem spindly, spurs, which are the short stems of the eventual flowers, grow from the bare parts of the vines. If you cut off the spurs, flower buds will not develop. When the plant does flower, leave the spent flowers alone. Do not pluck them off, which can damage the spurs. If you damage the spurs, next year's buds will not develop. Instead, let them fall off naturally. Note that the faded flowers can be very sticky, so you might want to place something underneath indoor wax plants to catch the blooms.