Merrill's Wax Plant (Merrill's hoya) care

Light

In the wild merrill's wax plant grows on the bright edge of a forest canopy, not in the canopy and not in the open. Indoors, that translates to within a metre of an unobstructed window, sheer curtain optional. Provide three to four hours of bright, filtered light daily; an east-facing window is ideal, as direct afternoon sun bleaches the glossy leaves. The fastest test: a hand held at the leaf casts a soft-edged shadow at noon — sharp shadow means too much sun, no shadow means too little light.

Watering

Aim for every 7–10 days in summer, every 14–21 days in winter for merrill's wax plant, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Allow the top half of the potting medium to dry before watering; as an epiphyte from humid lowland forest it needs consistent but never waterlogged moisture during the growing season.

Soil and pot

Merrill's Wax Plant grows best in well-draining epiphytic mix. Use equal parts orchid bark, perlite, and coco coir to replicate the loose, airy substrate clinging to tree bark in its native forest; always use a pot with drainage holes. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Merrill's Wax Plant sits happiest at around 60–80% humidity and 18–32°C (64–90°F). As a lowland Philippine epiphyte it needs reliably high humidity; a bathroom location with a bright window or a small humidifier keeps the foliage in peak condition. If you keep the room above 18–32°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed merrill's wax plant sparingly. Feed monthly in spring and summer with a half-strength balanced liquid fertiliser; switching to a low-nitrogen, high-potassium feed in late summer can help promote flowering. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on merrill's wax plant in the Growli community. Each is annotated with the most common cause so you know where to start.

• Bud drop in low humidity — If ambient humidity falls below 50% when buds are forming, Hoya merrillii will abort its buds; maintain humidity above 60% during the budding period and avoid moving the plant.
• Scale insects — Brown, shell-like scale can colonise stems and leaf undersides; scrape off manually and treat with horticultural oil or a systemic insecticide labelled for houseplants.

Propagation

Take stem-tip cuttings with two to three nodes and root in moist sphagnum moss in a warm (24–28°C), humid environment; rooting takes four to eight weeks. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Merrill's Wax Plant is pet-safe. The Hoya genus is listed as Non-Toxic to Dogs, Non-Toxic to Cats, and Non-Toxic to Horses by the ASPCA. Ingestion of large quantities of any plant material may still cause mild gastrointestinal upset. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Merrill's Wax Plant deep-dive guides

Every aspect of merrill's wax plant care, each with its own calibrated guide:

• Common merrill's wax plant problems & fixes
• Merrill's Wax Plant watering schedule
• Merrill's Wax Plant light requirements
• Best soil mix for merrill's wax plant
• Merrill's Wax Plant fertilizing guide
• When to repot merrill's wax plant
• How to propagate merrill's wax plant
• How to prune merrill's wax plant
• What's eating my merrill's wax plant?
• Merrill's Wax Plant growth rate & size
• Merrill's Wax Plant cold hardiness
• Merrill's Wax Plant temperature & humidity
• Is merrill's wax plant toxic to cats & dogs?
• Is merrill's wax plant toxic to cats?
• Is merrill's wax plant toxic to dogs?
• All 197 Hoya varieties

Featured in these plant shortlists

Merrill's Wax Plant qualifies for 10 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best trailing & climbing houseplants — Vining and trailing houseplants for shelves, hanging pots, and moss poles — selected by growth habit.
• Best humidity-loving houseplants — Houseplants that thrive in a bathroom, kitchen, or by a humidifier — selected by documented humidity preference.
• Best pet-safe trailing & hanging plants — Trailing and climbing plants the ASPCA lists as non-toxic to cats and dogs — safe for shelves and hanging pots in a pet home.
• Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
• Best pet-safe large indoor plants — Big, floor-standing houseplants the ASPCA lists as non-toxic to cats and dogs — a statement plant that is safe around pets.
• Best fragrant houseplants — Indoor plants with scented flowers or aromatic foliage — greenery you can smell, selected from our care library.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Merrill's Wax Plant is also known as Merrill's wax plant, Merrill's hoya, and Philippine wax plant.

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