Thunbergia erecta (Bush clock vine) care

Light

Most houseplants will scorch where thunbergia erecta thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Full sun to light shade. At least 4-6 hours of direct sun drives the heaviest flowering; in very hot climates light afternoon shade prevents scorch and flower drop. A plant moved abruptly from low light to direct sun bleaches in 48 hours — always acclimatise over a week.

Watering

Aim for when the top 2-3 cm of soil is dry, roughly every 4-7 days in growth for thunbergia erecta, 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. Keep evenly moist through the warm growing season; it dislikes drying out fully when budding. Reduce in cooler months. Avoid waterlogging, which causes root rot and yellowing.

Soil and pot

Thunbergia erecta grows best in fertile, well-drained loam. Rich, moisture-retentive but free-draining soil enriched with compost. In pots use a loam-based mix with added grit or perlite; slightly acidic to neutral pH suits it best. 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

Thunbergia erecta sits happiest at around 50-70% humidity and 18-30°C (64-86°F). Enjoys moderate to high humidity typical of the tropics. Tolerates average indoor humidity but flowers and foliage are lusher in a humid conservatory or sheltered patio. If you keep the room above 18 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 thunbergia erecta sparingly. Feed every 2-4 weeks through spring and summer with a balanced or slightly phosphorus-rich liquid fertiliser to sustain bloom. Ease off in autumn and stop in winter when growth slows. 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 thunbergia erecta in the Growli community. Each is annotated with the most common cause so you know where to start.

• Sparse flowering — Usually too little light or excess nitrogen. Move to full sun and switch to a phosphorus-rich feed to restore bloom.
• Leaf yellowing — Overwatering or poor drainage is the common cause; let the surface dry between waterings and ensure pots drain freely.
• Whitefly and spider mites — Common under glass and in dry air. Rinse foliage, raise humidity, and treat with insecticidal soap or neem if infestations build.
• Frost damage — Tender to even light frost; foliage blackens below about 2°C. Bring containers indoors or protect before the first frost.

Propagation

Easiest from softwood or semi-ripe stem cuttings taken in spring or summer, rooted in a warm, humid propagator. Also grown from seed, though cuttings flower faster and stay true. 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

Thunbergia erecta is mildly toxic to pets. Thunbergia erecta is not individually listed on the ASPCA's toxic or non-toxic plant database, nor is the genus Thunbergia. With no authoritative ASPCA non-toxic grounding, treat it as potentially mildly toxic if chewed, keep it away from pets, and verify with a vet if ingestion occurs. 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.

Thunbergia erecta deep-dive guides

Every aspect of thunbergia erecta care, each with its own calibrated guide:

• Thunbergia erecta watering schedule
• Thunbergia erecta light requirements
• Best soil mix for thunbergia erecta
• Thunbergia erecta fertilizing guide
• When to repot thunbergia erecta
• How to propagate thunbergia erecta
• Thunbergia erecta growth rate & size
• Thunbergia erecta cold hardiness
• Thunbergia erecta temperature & humidity
• Is thunbergia erecta toxic to cats & dogs?
• Is thunbergia erecta toxic to cats?
• Is thunbergia erecta toxic to dogs?

Featured in these plant shortlists

Thunbergia erecta qualifies for 2 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best humidity-loving houseplants — Houseplants that thrive in a bathroom, kitchen, or by a humidifier — selected by documented humidity preference.
• Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

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Thunbergia erecta is also commonly called Bush clock vine or King's mantle.

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