Fertilising guide
How to fertilise Colocasia 'Black Magic' (Colocasia esculenta 'Black Magic')— schedule & NPK
Also called Black Magic elephant ear, Black taro, Black elephant ear, Imperial taro.
More about colocasia 'black magic'
About Colocasia 'Black Magic'
Colocasia esculenta 'Black Magic' · also called Black Magic elephant ear, Black taro · tropical
Colocasia 'Black Magic' is a tuberous tropical grown for its huge heart-shaped, dusky purple-black leaves. It wants bright light, constantly moist to wet soil, warmth, and high humidity, and dies back below freezing. The ASPCA lists Colocasia esculenta as toxic to dogs and cats due to insoluble calcium oxalate crystals, so keep it away from pets.
Growth habit: Clump-forming, stemless tuberous perennial that sends up large, long-stalked, heart-shaped leaves from a central corm. Leaves emerge green and darken to a deep purple-black with age. Vigorous and fast-growing in warm, wet conditions.
What fertiliser colocasia 'black magic' actually wants — and why
Colocasia 'Black Magic' 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 'black magic': 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 'black magic', 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 'black magic':
Heavy feeder during active growth. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or work a slow-release feed into the soil at planting. Stop feeding in autumn and through winter dormancy. 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 'black magic' 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 'black magic'
Half strength every feed is the sweet spot for colocasia 'black magic': 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 'black magic' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the colocasia 'black magic' watering schedule.
Signs you are over-feeding colocasia 'black magic'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for colocasia 'black magic':
- 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 'black magic'
- 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 'black magic' 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 'black magic' 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 'black magic'
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 'black magic' — frequently asked questions
What fertiliser does colocasia 'black magic' 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 'Black Magic' 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 'black magic'?
Heavy feeder during active growth. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or work a slow-release feed into the soil at planting. Stop feeding in autumn and through winter dormancy. Heavy feeder during active growth. Apply a balanced liquid fertiliser every 2-4 weeks through spring and summer, or work a slow-release feed into the soil at planting. Stop feeding in autumn and through winter dormancy. 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 'black magic'?
Half strength every feed is the sweet spot for colocasia 'black magic': frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding colocasia 'black magic' 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 'black magic'?
Because you feed often, salts accumulate faster — flush the pot of colocasia 'black magic' with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Colocasia 'Black Magic' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water colocasia 'black magic' — 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