Fertilising guide
How to fertilise Colocasia 'Illustris' (Imperial Taro) (Colocasia esculenta 'Illustris')— schedule & NPK
Also called Imperial Taro, Imperial Elephant Ear, Black Elephant Ear, Illustris Elephant Ear.
More about colocasia 'illustris' (imperial taro)
About Colocasia 'Illustris' (Imperial Taro)
Colocasia esculenta 'Illustris' · also called Imperial Taro, Imperial Elephant Ear · tropical
Colocasia 'Illustris' is a tuberous tropical grown for huge heart-shaped, blackish-purple leaves veined in bright green. It wants warmth, bright light and constantly moist, rich soil, plus regular feeding. It is toxic: the ASPCA lists Colocasia esculenta as poisonous to cats, dogs and horses, so keep it well away from pets.
Growth habit: Clumping, tuberous (corm-forming) perennial with bold upright stalks holding large, downward-pointing heart-shaped leaves; spreads by offset cormels.
Watch for — Red spider mite: Encouraged by hot, dry indoor air; shows as fine webbing and a pale stippled mosaic on leaves. Raise humidity and treat with insecticidal soap or neem oil.
What fertiliser colocasia 'illustris' (imperial taro) actually wants — and why
Colocasia 'Illustris' (Imperial Taro) 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 colocasia 'illustris' (imperial taro): 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 colocasia 'illustris' (imperial taro), 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 colocasia 'illustris' (imperial taro):
Heavy feeder. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or enrich the soil with compost and slow-release feed; high-nitrogen feed supports the large leaves. Stop feeding in autumn and winter while growth slows or the plant is dormant. For a fast grower like this that means feeding regularly — about every 2-4 weeks — 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 colocasia 'illustris' (imperial taro) 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 colocasia 'illustris' (imperial taro)
Half strength every feed is the sweet spot for colocasia 'illustris' (imperial taro): 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 colocasia 'illustris' (imperial taro) first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the colocasia 'illustris' (imperial taro) watering schedule.
Signs you are over-feeding colocasia 'illustris' (imperial taro)
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for colocasia 'illustris' (imperial taro):
- 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 colocasia 'illustris' (imperial taro)
- 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 colocasia 'illustris' (imperial taro) 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 colocasia 'illustris' (imperial taro) 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 colocasia 'illustris' (imperial taro)
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 colocasia 'illustris' (imperial taro) — frequently asked questions
What fertiliser does colocasia 'illustris' (imperial taro) 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. Colocasia 'Illustris' (Imperial Taro) 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 colocasia 'illustris' (imperial taro)?
Heavy feeder. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or enrich the soil with compost and slow-release feed; high-nitrogen feed supports the large leaves. Stop feeding in autumn and winter while growth slows or the plant is dormant. Heavy feeder. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or enrich the soil with compost and slow-release feed; high-nitrogen feed supports the large leaves. Stop feeding in autumn and winter while growth slows or the plant is dormant. For a fast grower like this that means feeding regularly — about every 2-4 weeks — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
What strength of feed for colocasia 'illustris' (imperial taro)?
Half strength every feed is the sweet spot for colocasia 'illustris' (imperial taro): frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding colocasia 'illustris' (imperial taro) 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 colocasia 'illustris' (imperial taro)?
Because you feed often, salts accumulate faster — flush the pot of colocasia 'illustris' (imperial taro) with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Colocasia 'Illustris' (Imperial Taro) care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water colocasia 'illustris' (imperial taro) — 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 389 fertilising guides in the Growli library