Hoya Pubicalyx

How to care for Hoya Pubicalyx

Light

Hoya pubicalyx thrives in bright, indirect light for at least four to six hours per day. An east- or west-facing windowsill is ideal; a south-facing position works well if the plant is shielded from harsh midday sun by a sheer curtain. Insufficient light will reduce or prevent flowering and cause slow, leggy growth, whilst some direct morning sun is generally well tolerated and can encourage bud formation.

Watering

Allow the top third of the potting mix to dry out before watering thoroughly, then allow excess water to drain freely. Overwatering is the most common cause of decline; the succulent-like leaves store some moisture, giving the plant reasonable drought tolerance. Reduce watering frequency in autumn and winter when growth slows, but do not allow the mix to remain completely dry for extended periods.

Soil and potting

A well-draining, aerated mix is essential. A blend of perlite, orchid bark, and a small proportion of peat-free potting compost works well, providing both drainage and modest moisture retention. Hoya pubicalyx is an epiphyte in nature and resents sitting in dense, moisture-retaining soil. Slightly acidic to neutral pH (6.0 to 7.0) is suitable.

Feeding

Feed with a balanced, water-soluble fertiliser diluted to half strength once a month during the active growing season (spring through summer). Switching to a low-nitrogen, higher-phosphorus fertiliser in late summer may help promote flowering. Do not feed during autumn and winter when the plant is not actively growing.

Humidity and temperature

Hoya pubicalyx prefers humidity levels of 50% or above, though it tolerates average household humidity reasonably well. A pebble tray with water, regular light misting, or a nearby humidifier can help during dry periods. Keep the plant in temperatures between 16°C and 29°C and avoid cold draughts, sudden temperature fluctuations, and positions near radiators or air-conditioning vents. It will not tolerate frost.

Repotting

Repot every two to three years, or when roots visibly emerge from drainage holes. Choose a pot only one size larger than the current one, as Hoya pubicalyx often flowers more reliably when slightly root-bound. Spring is the best time to repot. Terracotta pots are beneficial as they allow excess moisture to evaporate through the walls.

Pruning

Pruning is generally done to manage size and shape rather than to encourage flowering. Importantly, never remove the spent flower stalks (peduncles), as the plant will produce new flower clusters from the same points each season. Trim back overly long vines in spring to promote bushier growth, and remove any dead or yellowing leaves as needed. Clean scissors or secateurs with rubbing alcohol before cutting.

Is Hoya Pubicalyx toxic?

Common problems

How to propagate

Stem cuttings in water or mix

Take a cutting of two to three nodes from a healthy, non-flowering stem, remove the lower leaves, and place in water or a moist mix of perlite and coir. Roots typically develop within three to six weeks at a temperature of 20-25°C.

Layering

Pin an existing stem node against a small pot of moist, well-draining mix while still attached to the parent plant. Once roots have formed at the node, sever the stem from the parent and allow the new plant to establish independently.

Where Hoya Pubicalyx comes from

Native to Philippines.

Story and origins

The genus name Hoya honours Thomas Hoy (c.1750-1822), head gardener to the Duke of Northumberland at Syon House, who was a notable cultivator of exotic plants in late 18th-century England. The species epithet pubicalyx is derived from the Latin 'pubis' (meaning downy or covered with fine hairs) and the Greek 'calyx' (the cup-like whorl of sepals of a flower), together describing the fine hairs that cover the calyx of the flowers.

Hoya pubicalyx was formally described by the Austrian botanist Rudolf Schlechter in 1913, based on specimens collected in the Philippines. The genus Hoya had been established almost a century earlier, and by the late 20th century a growing community of collectors known as Hoya enthusiasts or 'hoyaphiles' had developed considerable interest in the species and its numerous forms. In the Philippines and across much of South-East Asia, hoyas have traditionally been kept as good-luck plants, associated with prosperity and long life, and are commonly grown in homes and gardens. Hoya pubicalyx became widely commercially available in Europe and North America during the latter decades of the 20th century, valued for its reliability as an indoor plant and its showy, fragrant flowers.

Varieties to know

Hoya pubicalyx 'Pink Silver'

One of the most widely grown cultivars, featuring heavily silver-splashed leaves and pale to mid-pink flower clusters.

Hoya pubicalyx 'Red Buttons'

Produces particularly deep red to near-black flower clusters; leaves may show less silver variegation than 'Pink Silver'.

Hoya pubicalyx 'Splash'

Selected for pronounced silver flecking across the dark green foliage; flowers are typically a medium pink.

Hoya pubicalyx 'Royal Hawaiian Purple'

Bears very dark purple-black flowers with a striking contrasting centre; highly sought after by collectors.

Fun facts

• The flowers of Hoya pubicalyx are most fragrant during the evening and night, an adaptation thought to attract nocturnal moth pollinators.
• Like all hoyas, Hoya pubicalyx produces flowers on persistent structures called peduncles; removing these after flowering prevents future blooms from forming at that site.
• The silvery flecks on the leaves of many Hoya pubicalyx plants are caused by air pockets beneath the leaf surface, not by pigment.
• Hoya pubicalyx can bloom multiple times per year under consistently bright conditions, with mature plants producing dozens of umbels simultaneously.
• The genus Hoya contains over 500 recognised species, and Hoya pubicalyx is one of approximately 100 species native to the Philippines.

Hoya Pubicalyx FAQ