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The diversified forms of the Philippine Wax Plant or Hoyas

HoyaHoya is a genus of about 200-300 species of tropical climbing or trailing plants in the Apocynaceae (Dogbane) plant family.  The genus is native to southern Asia (India east to southern China and southward), Australia, and Polynesia. Common names for this genus are waxplant, waxvine, waxflower shooting star or simply Hoya. This genus was named by botanist Robert Brown, in honor of his friend, botanist Thomas Hoy.

Hoyas are evergreen climbing vines or shrubs growing to 1-10 m (or more with suitable support in trees). They have simple opposite leaves 5-30 cm long that are typically succulent, and in many species are flecked with irregular small silvery spots.

The flowers appear in axillary umbellate clusters at the apex of 2-3 cm peduncles, with repeated clusters of flowers developing sequentially on each peduncle. The flowering peduncles get 2-3 mm longer with each flowering, and can eventually reach 7 cm or more long. The base of the peduncle is smooth, with growth subsequent to the first flowering of the peduncle is rough with numerous tiny bracts. Each flower is about 1 cm diameter, with five thick, waxy, triangular petals.  Colors range from white to pink or yellow. They are sweetly scented and produce abundant nectar.

Many species of Hoya are popular houseplants in temperate areas (especially H. carnosa), grown for their attractive foliage and strongly scented flowers. Numerous cultivars have been selected for garden use. Hoyas grow well indoors, preferring bright but not direct sunlight, but will tolerate fairly low light levels at the expense of rapid growth and blooming. They are perfect plants for hanging baskets or as hanging plants.  Hoyas commonly sold in nurseries as houseplants include cultivars of H. carnosa (Krimson Queen, Hindu Rope − compacta), H. pubicalyx (often mislabeled as carnosa), and H. kerrii. Hoyas are easy to purchase through the internet, and are commonly sold as cuttings, either rooted or unrooted.

Hoya flowers are just as varied as the leaves, despite the fact that all are shaped like five pointed stars. They grow in umbels, like that of the Santan flower.  Each umbel usually is composed of about 30  flowers, Individual flowers range in size from as small as four to five millimetres in diameter (like Hoya bilobata ) to well over three inches in diameter ( like Hoya imperialis ). The number of flowers per umbel varies from one to 55 or even more. Hoya flowers also vary in textures as well as size, and color.  With these characteristics, Hoyas are very interesting to collect.  As of present, there are about 51 identified species of Hoya in the Philippines .


Hoya plants are very easy to grow and cultivate, here are some of its cultural requirements growing tips:


Light. Hoya plants grow in diffused bright light (about 50% light). Protect it from direct sun. 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 flooding to wash away excess salts. Use soft water like rain water, or water low in salts. Provide a humid environment by grouping Hoya plants along with other shade-loving plants and watering them regularly. Allow ventilation and air-movement between plants at all times to prevent rotting of leaves.


Temperature.  Hoya plants grow well in normal room temperature or in the lowland temperature.


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 plant needs a bigger pot. They are usually potted as a hanging plant. For non-hanging pots, place wooden, wire or plastic coated stakes as vines tend to crawl up supports. Roll long vines around the stakes.


Fertilization. Hoya plants are light feeders. Spray a dilute solution of balanced fertilizer high in potassium, in order to continuously produce flowers. Apply about ¼ or less of control release fertilizers in the sides of pots.


Pruning. Prune back very long vines to induce branching. However, long vines are usually not cut, but rather trained and rolled together around stakes or wire hangers attached to the pot, as the long vines are the ones which produces flowers.


Pest & Diseases. Hoyas are usually susceptible to sucking insects like mites, aphids and white flies. If insect infestation occurs, spray with a dilute solution of insecticide like Malathion, Sevin or Lannate. To prevent leaf spots or rot, allow ventilation among plants, allow proper spacing and keep plants dry between watering. Spray a weak solution of Captan or Dithane fungicide during the rainy season as a prophylactic to prevent fungal diseases.


Propagation. Hoyas are usually propagated by stem cuttings with 2 to 3 nodes. Leaves from the lower nodes are usually removed before the stem cuttings are inserted into the potting media. Stem cuttings are 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 can 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.

Hoya are interesting plants to collect, and some garden clubs, local and abroad, are formed just to cater for the growing of this plant. Conservation is also needed for this group of plants.