Fertilising guide
How to fertilise Red Clockvine (Thunbergia coccinea)— schedule & NPK
Also called Red Clockvine, Scarlet Clockvine, Scarlet Thunbergia.
More about red clockvine
About Red Clockvine
Thunbergia coccinea · also called Red Clockvine, Scarlet Clockvine · tropical
Thunbergia coccinea is a stunning tropical vine from the Indian subcontinent bearing pendant racemes of scarlet-orange tubular flowers with a yellow throat from autumn through spring. Fast-growing and hummingbird-attracting, it excels on pergolas and large trellises in warm climates or as a spectacular conservatory climber in cooler regions.
Growth habit: Vigorous evergreen perennial twining vine producing long pendant flower clusters on the previous season's wood
What fertiliser red clockvine actually wants — and why
Red Clockvine is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for red clockvine: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed red clockvine, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For red clockvine:
Apply a balanced liquid fertiliser every 2–3 weeks throughout the main growing season (late spring to early autumn). Switch to a low-nitrogen, higher-potassium formulation from late summer to encourage flowering. Withhold feed in winter. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when red clockvine is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for red clockvine
Half strength is the safe default for red clockvine — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water red clockvine first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the red clockvine watering schedule.
Signs you are over-feeding red clockvine
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for red clockvine:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding red clockvine
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full red clockvine care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of red clockvine with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for red clockvine
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising red clockvine — frequently asked questions
What fertiliser does red clockvine need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Red Clockvine is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed red clockvine?
Apply a balanced liquid fertiliser every 2–3 weeks throughout the main growing season (late spring to early autumn). Switch to a low-nitrogen, higher-potassium formulation from late summer to encourage flowering. Withhold feed in winter. Apply a balanced liquid fertiliser every 2–3 weeks throughout the main growing season (late spring to early autumn). Switch to a low-nitrogen, higher-potassium formulation from late summer to encourage flowering. Withhold feed in winter. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for red clockvine?
Half strength is the safe default for red clockvine — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding red clockvine look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding red clockvine year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of red clockvine?
Flush the pot of red clockvine with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Red Clockvine care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water red clockvine — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise comparettia falcata
- How to fertilise ionopsis utricularioides
- How to fertilise lepanthes telipogoniflora
- All 8452 fertilising guides in the Growli library