Hoya pubicalyx 'Black Dragon'

Botanical Name — Hoya pubicalyx 'Black Dragon'
Common Name — Wax Plant, Porcelain Flower, Black Dragon Hoya
Plant Family — Asclepiadaceae

Background

Hoya pubicalyx 'Black Dragon' is a nursery cultivar of Hoya pubicalyx, a vining epiphyte native to the Philippines. Its thick, waxy leaves love dappled and indirect light. This variety is prized by collectors for the coloration of its flowers, which are black and crimson-purple and blossom, as all Hoya flowers do, in a seamless, arcing dome.

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Growth Requirements

Sun

• Hoya pubicalyx prefers a few hours of direct sun or dappled sun when kept indoors. Though it will survive in bright indirect light only, giving it a few hours of sun will boost growth and encourage flowering. Indoors, a sunny window with eastern western exposure is a great spot.
• Avoid intense afternoon sun. This can burn the leaves.

Temperature/ Humidity

• Hoya pubicalyx can tolerate high temperatures in the 70s and 80s or higher. They are not cold hardy, however. Avoid temperatures below 50 ºF.
• Hoya plants thrive in high humidity, though they are tolerant of more moderate, indoor humidity levels. Extremely arid climates may cause dryness at the tips of leaves.

Water

• Though Hoya plants can withstand some drought, during the growing season they prefer a consistent watering schedule. Water regularly during the growth period. Allow the soil to dry out at least halfway before watering thoroughly.

Soil/Roots

• Hoya pubicalyx prefer a well-draining, yet moisture-retentive soil. Regular potting soil works just fine. Amend soil with coco coir and compost to improve moisture retention and supplement soil nutrients.
• These plants are epiphytes, meaning they grow attached to trees. Their growing substrate in their natural environment is mainly composed of materials such as decomposing bark, leaves, and flowers.

Flowering

• Hoya pubicalyx 'Black Dragon' produce small, sweet-smelling flowers in clusters of 10 to 30. Flowers are star-shaped, and typically black and violet-red. Flowers are covered in tiny hairs giving them a fuzzy appearance up close.
• Flowers appear from late spring to summer. Give Hoya plants optimal conditions to improve their chances of flowering.

Fertilization

• You can fertilize your 'Black Dragon' with a water-soluble balanced fertilizer once every two weeks, only during the active growing season.

Propagation

• Hoya pubicalyx can be easily propagated from stem cuttings, rooted in soil or water. Cuttings taken from more recent growth will have the best chances of success.

Health

Diseases

• Hoya plants are pretty hardy plants, though they can fall susceptible to some fungal infections if they are not receiving proper care. Botrytis blight appears as large, gray-colored spotting at the center or margins of infected plants. Wilting and black or brown stem lesions are another symptom to look out for. Copper or sulfur fungicides can be helpful in treating.
• Aphids, mealy bugs and other sap-sucking pests can also be of concern and can vector other fungal or bacterial diseases. Treat this plant with diluted neem oil or insecticidal soap at the first sign of an infestation.
• Root rot is another concern and is triggered by overwatering. With this plant it is always best to err on the side of underwatering.

Maintenance (pruning, legginess, repotting)

• Hoya plants require little maintenance. Prune away unhealthy looking parts of the plant.
• Hoyas prefer to be somewhat rootbound. Repotting should only be necessary once every two to three years. Soil can be replenished with fertilizer during the growing season.

Toxicity

• Hoya pubicalyx are considered non-toxic to humans and pets, though ingesting them can cause gastrointestinal discomfort and vomiting. Best to keep these plants out of reach of children and pets.