GardenLine | House Plants | The Hoya: Long-Lived and Trouble-Free

Few house plants are easier to grow than the hoya. This tough tropical plant adapts readily to conditions in almost any home, forming a massive vine covered in dark green, leathery leaves. It thrives with little care, will expand to fill an entire window and will bloom each summer for many years.

About one hundred species of hoya are native to Eastern Asia and Australia. The common house plant, Hoya carnosa, was named for Thomas Hoym, gardener to the Duke of Northumberland at the end of the 18th century. 'Carnosa' refers to the plants fleshy leaves. As is typical for member of the milkweed family, the hoya exudes a sticky sap if cut or damaged.

The plant is easily started from stem cuttings. A portion of stem including one or more pairs of leaves will quickly produce roots in water or damp sand. Those who desire a larger plant may take cuttings of 1 m (3.2 ft) or more. These provide an almost instant vine once planted.

New growth appears first as leafless extensions up to 2 m (6.4 ft) long. Once fully elongated, new portions of the vine produces pairs of leaves along the stem. Such a growth habit permits hoyas growing in the wild to extend new growth long distances through the branches of trees before becoming weighed down by leaves.

Flowers can only be expected on plants four years and older. Clusters of attractive, star-shaped, pink-white blossoms are produced in summer. The delicate flowers appear to be made of porcelain, and are truly unique. In fact, those seeing hoya blossoms for the first time may need to touch them to determine that they are real.

Since flowers clusters are produced on the same short stems yearly, it is critical that the flowering spurs be left in place after flowering is complete. A common criticism of the flowers is the heady scent they release each evening. Fragrance from a blooming hoya can easily fill a large house. Some people choose to place the plant outdoors at night, or remove the flowers entirely.

Infrequent repotting does not seem to impair the plant's growth, and even very large plants seldom require a pot larger than 12.7 or 15.24 cm (5 or 6 in.) in diameter. Hoyas should be kept evenly moist during the active growth period in spring and summer. Water can be decreased in autumn and winter to permit drying of the soil between waterings. Fleshy leaves provide the plant with the ability to withstand a considerable degree of drying. Should the plant become excessively dry, the leaves will pucker inward as they lose water. Though drying to this extent is not desirable, full recovery is likely once the plant is watered.

An east and west window is ideal for the hoya. Direct southern exposure may produce a greater quantity of flowers, but may also result in rigid, yellow leaves. Insufficient light causes dark green leaves to be produced, but will prevent any flowering.

The hoya is a notoriously long-lived and trouble-free plant. Given minimal care and time to establish, it will develop into a large, attractive plant that anyone can grow.

Baldwin is a graduate student in the Department of Horticulture Science. This column is provided as an extension service by the Extension Division and the Department of Horticulture Science, University of Saskatchewan.

© 1995 Brian Baldwin

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.