Hoya kerrii

Collected on Doi Suthep in northern Thailand

Hoya kerrii was described by William Grant Craib in 1911 from a plant collected by Arthur Francis George Kerr on Doi Suthep near Chiang Mai. The material was cultivated at Kew and flowered there in August 1911, allowing its heart-shaped leaves and flowers to be described together.

The species ranges from Indo-China to western Malesia. In Thailand it grows from low elevations to about 1,300 m in seasonal hardwood and dipterocarp-oak forest, including limestone areas; the type locality was around 390 m. It climbs and roots on trees where water drains quickly even within humid tropical forest.

Watering and root care for epiphytic vines

• Water: Allow nearly the entire root mix to dry. The very thick leaves store water, but prolonged extreme drying can kill fine roots. Once the mix is nearly dry and the pot feels light, soak the entire root ball and allow it to drain completely.
• Light: Choose a generously lit position with protection from harsh direct sun so the vine can produce sturdy growth and mature leaves. Broad heart-shaped blades can scorch on the exposed side if moved suddenly into strong direct sun, so increase intensity gradually.
• Temperature and airflow: Warm indoor conditions support active growth. Keep it frost-free with moving air.
• Propagation: Take a stem cutting with at least one node and an axillary growth point. Start the node in water or tuck it into damp coarse bark and perlite, then keep the cutting warm in bright filtered light while roots establish.

Understanding problems on Hoya kerrii

• Soft or wrinkled leaves: Both severe dryness and root rot reduce leaf firmness. Check the mix, pot weight and roots before adding water. Soak the root ball if it is dry and the roots are healthy. If roots are soft or hollow, cut them away and replace the wet, compact mix. Translucent or dark patches after contact with a cold window are cold damage. A soft base above wet mix points to decay.
• Pests on broad leaves and nodes: Look for mealybug wax, scale bumps, sticky residue, mite stippling or thrips scars, especially where new vines meet the support. Isolate the plant and wipe the broad leaves carefully to remove visible pests. Clean the stake or trellis, then treat the broad leaf surfaces and exposed nodes with a product suitable for the insect or mite present. Check the stem joints again later for young pests hidden there.
• A single heart leaf does not vine: A rooted leaf usually remains a single leaf when it contains no piece of stem. A small bud where the leaf joins the stem is needed for a new vine. Healthy roots do not guarantee a future shoot. This is a structural limitation rather than a care problem.
• Corky spots: Raised tan or brown patches often follow oedema, a noninfectious disorder that develops when water uptake exceeds water loss. Improve warmth and air movement, let the coarse mix dry substantially and avoid sudden heavy watering after a long dry period. Existing corking is permanent.

Hoya kerrii is non-toxic to people and pets

• This plant is non-toxic to people, cats and dogs.
• Chewing a large amount can still cause an upset stomach.
• If a large amount is eaten and symptoms continue, contact a veterinarian or medical professional.

Where does the name Hoya kerrii come from?

Hoya honours the English gardener Thomas Hoy. Hoya kerrii honours Irish physician and plant collector Arthur Francis George Kerr.

Robert Brown established the genus Hoya in 1810 in Prodromus Florae Novae Hollandiae, page 459.

William Grant Craib first described Hoya kerrii in 1911 in Bulletin of Miscellaneous Information, Kew, volume 1911, page 418.