Fertilising guide
How to fertilise Henderson's Allamanda (Allamanda cathartica 'Hendersonii')— schedule & NPK
Also called Henderson's Allamanda, Golden Trumpet Vine, Yellow Allamanda.
More about henderson's allamanda
About Henderson's Allamanda
Allamanda cathartica 'Hendersonii' · also called Henderson's Allamanda, Golden Trumpet Vine · tropical
Henderson's Allamanda is a vigorous tropical vine bearing exceptionally large golden-yellow trumpet flowers up to 13 cm (5 in) across, opening from distinctive bronze buds. It climbs to 4–8 m in tropical gardens and blooms almost continuously in full sun. A heavy feeder requiring rich, well-drained soil, it is toxic to pets and humans.
Growth habit: Vigorous twining vine / climber
Watch for — Sparse or no flowering: Almost always caused by insufficient direct sunlight. Move to a position with unobstructed full sun. Excess nitrogen fertiliser also diverts energy into leaf production; switching to a bloom-booster (high P:K ratio) in summer restores flowering.
What fertiliser henderson's allamanda actually wants — and why
Henderson's Allamanda is a genuinely hungry tropical — in bright warmth it pushes growth fast and rewards a regular half-strength balanced feed all season.
A balanced liquid feed (even N-P-K) or a slightly nitrogen-leaning foliage feed — this is a big-leaved foliage plant putting on real size, so it wants steady nitrogen for lush leaves, not a bloom 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 henderson's allamanda: 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 henderson's allamanda, 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 henderson's allamanda:
A heavy feeder. Apply a balanced liquid fertiliser every 2–3 weeks throughout the growing season (spring to early autumn). Switch to a high-phosphorus, low-nitrogen formula in midsummer to encourage bud set over vegetative growth. Withhold feeding in winter during the rest period. For a fast grower like this that means feeding regularly — about sparingly through the growing season — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
The dormant-season rule matters more than the exact interval: skip feeding entirely when henderson's allamanda 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 henderson's allamanda
Half strength every feed is the sweet spot for henderson's allamanda: frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
Feeding always goes onto already-damp soil, never dry roots — water henderson's allamanda first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the henderson's allamanda watering schedule.
Signs you are over-feeding henderson's allamanda
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for henderson's allamanda:
- Brown, scorched leaf tips and margins despite correct watering.
- A white salt crust on the soil or around the pot edge.
- Sudden leaf yellowing and drop shortly after a strong feed.
- Soft, weak, over-stretched growth that cannot support itself.
Signs you are under-feeding henderson's allamanda
- New leaves coming in noticeably smaller than older ones.
- Pale, yellow-green older leaves and slow growth through peak summer.
- A general loss of vigour and gloss in a plant that should be racing away.
If the symptoms point at watering, light or roots rather than nutrition, the full henderson's allamanda care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Because you feed often, salts accumulate faster — flush the pot of henderson's allamanda with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Organic vs synthetic feeds for henderson's allamanda
Organic options
A diluted seaweed or fish-and-seaweed feed plus a yearly top-dress of worm castings supports fast growth without burn risk. UK: Westland seaweed or Baby Bio Organic; US: Neptune's Harvest or Espoma Indoor!.
Synthetic / liquid feeds
A balanced houseplant liquid at half strength applied frequently — UK: Baby Bio, Phostrogen or Westland Houseplant Feed; US: Miracle-Gro Indoor Plant Food or Dyna-Gro Foliage-Pro for steady leafy growth.
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 henderson's allamanda — frequently asked questions
What fertiliser does henderson's allamanda need?
A balanced liquid feed (even N-P-K) or a slightly nitrogen-leaning foliage feed — this is a big-leaved foliage plant putting on real size, so it wants steady nitrogen for lush leaves, not a bloom formula. Henderson's Allamanda is a genuinely hungry tropical — in bright warmth it pushes growth fast and rewards a regular half-strength balanced feed all season.
How often should I feed henderson's allamanda?
A heavy feeder. Apply a balanced liquid fertiliser every 2–3 weeks throughout the growing season (spring to early autumn). Switch to a high-phosphorus, low-nitrogen formula in midsummer to encourage bud set over vegetative growth. Withhold feeding in winter during the rest period. A heavy feeder. Apply a balanced liquid fertiliser every 2–3 weeks throughout the growing season (spring to early autumn). Switch to a high-phosphorus, low-nitrogen formula in midsummer to encourage bud set over vegetative growth. Withhold feeding in winter during the rest period. For a fast grower like this that means feeding regularly — about sparingly through the growing season — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
What strength of feed for henderson's allamanda?
Half strength every feed is the sweet spot for henderson's allamanda: frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding henderson's allamanda look like?
Brown, scorched leaf tips and margins despite correct watering. A white salt crust on the soil or around the pot edge. Sudden leaf yellowing and drop shortly after a strong feed. Soft, weak, over-stretched growth that cannot support itself. The mistake here is the opposite of most houseplants: under-feeding a fast tropical in peak season starves it, leaving small, pale new leaves and slow growth — but full-strength doses still burn it, so feed often and weak, not occasionally and strong.
Should I flush the soil of henderson's allamanda?
Because you feed often, salts accumulate faster — flush the pot of henderson's allamanda with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Henderson's Allamanda care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water henderson's allamanda — 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 firebush
- How to fertilise panama rose shrub
- How to fertilise firecracker plant
- All 6887 fertilising guides in the Growli library