The Hoya carnosa, also known as the wax plant or porcelain flower, is a species of flowering plants in the Apocynaceae family. Originating from East Asia, this plant is a popular houseplant because of its attractive waxy leaves and sweetly scented flowers. It thrives well in pots and hanging baskets, making it a versatile choice for any interior.
Hoya carnosa has been cultivated for over 200 years and has given rise to many different varieties that vary in both leaf shape and flower color. In the United Kingdom, this plant has received the Royal Horticultural Society’s Award of Garden Merit, a recognition of its beauty and durability.
Hoya carnosa easily forms succulent shoots with smooth, light gray, and bare surfaces that can twist and climb. The perennial leaves are broadly ovate to elongated or heart-shaped, slightly succulent, fleshy with a waxy sheen. The leaves typically measure 3-5 cm in width and 3.5-13 cm in length with a leaf stalk of about 1-1.5 cm.
The inflorescence consists of many small flowers, hanging or standing more upright and clustered in a umbel. The flowers are typically pink, but can range from almost white to dark pink; they are star-shaped and appear as if they are made of porcelain or wax, hence giving the plant its common names. The flowers have a diameter of 1.5-2 cm and are covered in small hairs, giving them a fuzzy sheen. They are strongly scented and can produce excess nectar that drips from the flowers.
Hoya carnosa blooms from specialized perennial stems, known as spurs. The flowers are produced on these spurs every year, so they should not be removed. The plant blooms from spring to late summer and can produce umbels with 10-50 small star-shaped flowers that mature gradually over 2-3 weeks.
This species is found in East India, southern China (Fujian, Guangdong, and Yunnan provinces as well as Guangxi autonomous region), Taiwan, Myanmar, Vietnam, Malaysia, the Japanese islands of Kyushu and Ryukyu, and the Fiji islands. Hoya carnosa grows in humid subtropical forests.
Hoya carnosa prefers indirect light, but can also tolerate less light. It thrives at temperatures between 16-29 °C and can be propagated by air layering or stem cuttings. It benefits from an open potting mix that allows air to reach the roots. Typical mixtures include large drainage materials such as perlite, pumice, or ceramic balls. The plant should be fertilized regularly with fertilizer suitable for epiphytic plants.
There is a persistent myth that hoyas prefer to be root bound in a small pot, which is said to promote flowering. Studies from the University of Georgia have shown that Hoya carnosa is effective at removing pollutants from indoor environments, making it a healthy addition to the home.
A variant of Hoya, known as Hoya carnosa var. compacta or Hindu rope plant, is characterized by its folded, curled leaves that grow along vines resembling ropes. The flowers on this variant tend to have a pinkish hue.
With its beauty and versatility, Hoya carnosa is the perfect houseplant that adds both aesthetic value and cleaner air to your home.