|Classified:||Teijsm. & Binn, 1863|
|Propagation:||From seeds, cutting, layering|
|Adult size:||over 1-2 m indoors|
|Watering:||Let the soil completely dry between waterings|
|Fertilization:||Monthly during active growth|
|Soil:||Very well drained|
|Humidity:||High humidity required|
|See more Hoya|
Hoya uncinata is a vining epiphytic plant in the dogbane family Apocynaceae. It has attractive waxy foliage. Native to the islands of Sumatra and Java, it is a difficult Hoya to grow and not recommended for beginners, with a vining and climbing habit.
The genus Hoya was named after the botanist Thomas Hoy.
Padangensis is named after Pandang in Sumatra. Uncinata means 'hooked' and refers to the shape of the flowers.
The inflorescence is made up of multiple flowers, hanging or more upright, grouped in an umbel. The flowers are light cream with maroon hues. They are star-shaped, and are borne in clusters that look like they are made of wax. The flower's surface has a smooth appearance without the tiny hairs seen in many other Hoya. They are heavily scented.
Like all species of Hoya, H. uncinata flowers from spurs. These appear from the axils of the leaves and stem; flowers may not be produced when the spurs first appear, but in time buds emerge from the tips. Each season new flowers are produced on these same spurs, so they should not be damaged or removed.
The plant flowers from spring to late summer, it can produce umbels of 5 to 15 small star-shaped flowers that mature gradually (2 to 3 weeks) on the same peduncle. The scent is strongest in the early evening.
H. uncinata has unremarkable firm matte leaves with a green color.
H. uncinata wants bright, indirect light. It can tolerate some morning or evening light but avoid hot midday sun or the leaves will yellow and scorch.
Use a very well draining soil mix and re-pot at least every other year with a coarse, extremely well draining substrate (see hoya soil). Water thoroughly, allowing excess to drain. A waterlogged soil will lead to yellowing leaves, followed by root rot and death. Never allow the plant's roots to sit in standing water.
H. uncinata is not hardy and foliage will burn and die if exposed to frost. It can handle continual temperatures down to 15°C (60°F) and growth will suffer in temperatures continually above 35°C (95°F).
Yellowing leaves are a sign of too much water. Ensure the pot has good drainage and allow the surface of the soil to dry between watering. If the soil is staying too moist for too long, consider repotting into a mix which dries more quickly - see hoya soil.
Thin or wrinkling leaves
Thin leaves are a sign of stress in Hoya. Check the plant has good drainage and isn't sitting in water or compacted soil.
Wrinkled leaves may indicate the plant is thirsty and needs water. If the plant has wrinkled leaves and the soil is being kept moist it could mean the plant's roots are rotting. Gently remove the plant from its container and check that the roots are healthy.
Dropping new leaves
If your H. uncinata is actively growing but drops any new leaves before they have fully matured it is likely a sign of water stress. Did you recently soak the plant? Or have you been letting the Hoya dry out for too long in between waterings? Try adjusting your watering schedule to reduce the large swings in conditions for the plant.
Hoya that are actively growing or about to flower require more water than a Hoya that is sitting dormant.
Slow or no growth
Hoya can be temperamental plants. A change in environment may send the plant into a partial dormancy and growth will stop for weeks or months. Give the plant time to adjust to a change in its surroundings, especially if it has recently been brought home from the store or been moved from outside in, or visa versa.
Hoya, especially those with thicker leaves, can occasionally produce foliage that is misshapen. This is normally because of stress during the production of the leaf - maybe the plant was overwatered, the temperature was especially high or low or the plant was moved into a new environment. New growth on the plant should be the 'right' shape, assuming the conditions are more consistent in future.
Vines dying back
Many Hoya send out leafless vines to seek out spots of sunlight and branches to twine and climb. Given time and light, these vines will produce leaves. However sometimes the plant will decide the vine is not viable and it will die back - if you see the tip of the vine shrivel then it is safe to cut it off. Just make sure it isn't a peduncle or you will be removing a flowering point for the Hoya.
H. uncinata can be affected by spider mites, scale, thrips. The succulent foliage makes mealybugs a particular issue.
Hoya are commonly propagated from cuttings. The cuttings can be rooted in water, sphagnum moss or directly into soil. See hoya propagation for a detailed guide.