Growing Hoya Plants

MANILA, Philippines - Hoya is locally known as Shooting Star. It is also known as Wax flower, Wax Vine or Wax Plant. It is usually a climbing or trailing plant with generally thick, shiny, fleshy leaves and clusters of waxy star-shaped flowers. They are the most colorful group of plants under the Asclepiadaceae plant family, in which other plants like the common milkweed, the succulent Stapeliads and the Dischidias belong. They have pollen in gelatinous masses called pollinia, similar to orchids.

Robert Brown, famous for his discovery of the ‘Brownian Movement’ in Physics, named the plant in honor of his friend and fellow botanist Thomas Hoy, who worked as head gardener for the Duke of Northumberland at Scion House, England.

There are about 200 to 300 species of Hoyas that are native to Asia, Polynesia and Australia. It is popularly grown as a garden plant or house plant, due to its attractive foliage and sometimes scented flowers. Hoyas are found throughout the Philippines at all altitudes, usually growing on tree trunks and branches. There are about 51 species of Hoya listed in the Philippines and more species may still be discovered.

Cultural Requirements for Hoya Plants

Light – Hoya plants grow best under diffused bright light (about 50% light). Direct unfiltered sun may burn the plant. For indoor cultivation, three to four hours of bright light a day are essential for healthy growth and flowering.

Watering & Humidity – Water plants regularly and do not allow them to dry out completely. They can benefit from moist media and occasional flushing to wash away excess salts. Rain water is best for Hoyas or water low in salts may be used. Provide a humid environment by grouping Hoya plants along with other shade-loving plants and do water them regularly. Good ventilation prevents diseases of Hoyas.

Temperature – Hoya plants grows well at normal room temperature or under lowland temperatures.

Potting Technique – Plant Hoya plants in plastic or clay pots with any porous and low-fertility mixes like mixture of coconut husk cubes or coconut dust, charcoal, sphagnum moss, tree fern fiber and paslak (chopped roots of Birds nest fern). The media should be well drained and open enough so that air reaches the roots. Repot if the media breaks down, or when the plants needs a bigger pot. They are usually potted as hanging plants. For regular pots, place wooden, wire or plastic coated stakes as vines tend to crawl up the supports. Wind long vines around the stakes or on circular trellis.

Fertilization – Hoya plants are medium to heavy feeders. Spray dilute solution of balanced fertilizer high in potassium to improve flowering. Apply about a quarter or less of controlled-release fertilizers per pot as side dressing.

Pruning – Prune back long unruly vines to induce branching. Most growers however do not cut old stems of Hoyas because the flowers reappear in the same inflorescence for several years.

Pest & Diseases – Hoyas are usually susceptible to sucking insects like scale insects, mealy bugs, aphids and white flies. If insect infestation occurs, spray with a dilute solution of insecticide like Vertimec, Ascend or Lorsban. Do not cramp up plants. Allow proper spacing and keep plants dry between watering. Healthy Hoyas seldom get sick.   

Propagation – Hoyas are usually propagated by stem cuttings with 2 to 3 nodes. The cuttings normally root within the month relatively easy to root especially when rooting is done under mist condition or when the pot is wrapped in clear plastic bag. Cuttings root best in a growing media that retain a lot of moisture like coconut coir dust, coconut husk, charcoal and crushed fern chips.

Hoyas may also be propagated by seeds. Some species readily produce seed capsules containing tufted seeds which burst when mature and are wind dispersed. Care must be observed by covering seed capsules with a gauze or nylon stocking when nearing maturity. Once mature, the seed capsule slips and the seeds can be removed. Seeds can be sown and germinated in a pot with a mixture of coir dust and sand. Transplant seedlings when they have developed true leaves.

Hoyas are interesting plants to collect, and some garden clubs, local and abroad, are formed just to focus on cultivation of this plant. Conservation is also needed for this group of plants.