Fertilising guide
How to fertilise Amorphophallus maximus (Amorphophallus maximus)— schedule & NPK
Also called maximum voodoo lily, giant amorphophallus.
More about amorphophallus maximus
About Amorphophallus maximus
Amorphophallus maximus · also called maximum voodoo lily, giant amorphophallus · tropical
Amorphophallus maximus is a large tropical African tuberous aroid grown from a big corm. Each season it sends up a single, broadly divided umbrella leaf on a tall mottled petiole, dying back to a dormant corm afterwards. It needs warmth, humidity, bright filtered light and very free-draining soil, and rewards patient growers with an architectural seasonal leaf and occasional malodorous bloom.
Growth habit: Large tuberous, seasonally dormant aroid producing a single, broadly divided umbrella leaf per cycle on a tall mottled petiole; an inflorescence may appear separately before the leaf.
What fertiliser amorphophallus maximus actually wants — and why
Amorphophallus maximus 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 amorphophallus maximus: 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 amorphophallus maximus, 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 amorphophallus maximus:
Feed every 2-3 weeks during active leaf growth with a balanced liquid fertiliser at half strength to bulk up the corm. Stop feeding once the leaf starts to die back into dormancy. Treat that as every 2-3 weeks 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 amorphophallus maximus 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 amorphophallus maximus
Half strength is the safe default for amorphophallus maximus — 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 amorphophallus maximus first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the amorphophallus maximus watering schedule.
Signs you are over-feeding amorphophallus maximus
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for amorphophallus maximus:
- 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 amorphophallus maximus
- 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 amorphophallus maximus care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of amorphophallus maximus 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 amorphophallus maximus
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 amorphophallus maximus — frequently asked questions
What fertiliser does amorphophallus maximus 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. Amorphophallus maximus 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 amorphophallus maximus?
Feed every 2-3 weeks during active leaf growth with a balanced liquid fertiliser at half strength to bulk up the corm. Stop feeding once the leaf starts to die back into dormancy. Feed every 2-3 weeks during active leaf growth with a balanced liquid fertiliser at half strength to bulk up the corm. Stop feeding once the leaf starts to die back into dormancy. Treat that as every 2-3 weeks 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 amorphophallus maximus?
Half strength is the safe default for amorphophallus maximus — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding amorphophallus maximus 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 amorphophallus maximus 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 amorphophallus maximus?
Flush the pot of amorphophallus maximus 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
- Amorphophallus maximus care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water amorphophallus maximus — 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 monstera
- How to fertilise pothos
- How to fertilise fiddle leaf fig
- All 5561 fertilising guides in the Growli library