Fertilising guide
How to fertilise Calathea Undulata (Goeppertia undulata)— schedule & NPK
Also called wavy calathea, undulate calathea.
More about calathea undulata
About Calathea Undulata
Goeppertia undulata · also called wavy calathea, undulate calathea · houseplant
A small, compact prayer plant with softly rippled, oval leaves patterned in a pale central feather over deep green and flushed purple beneath. The wavy margins give it its name. It is a true humidity- and moisture-lover that resents hard water, stays low and tidy, folds its leaves at night, and is non-toxic to pets.
Growth habit: Compact clumping foliage plant with small, rippled, oval leaves on short stalks forming a dense low mound; folds its leaves upward at night.
What fertiliser calathea undulata actually wants — and why
Calathea Undulata 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 calathea undulata: 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 calathea undulata, 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 calathea undulata:
Feed every 3-4 weeks in spring and summer with a balanced houseplant fertiliser at half strength. Flush the soil periodically to clear salts, and stop feeding in autumn and winter. For a fast grower like this that means feeding regularly — about every 3-4 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 calathea undulata 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 calathea undulata
Half strength every feed is the sweet spot for calathea undulata: 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 calathea undulata first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the calathea undulata watering schedule.
Signs you are over-feeding calathea undulata
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for calathea undulata:
- 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 calathea undulata
- 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 calathea undulata 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 calathea undulata 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 calathea undulata
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 calathea undulata — frequently asked questions
What fertiliser does calathea undulata 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. Calathea Undulata 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 calathea undulata?
Feed every 3-4 weeks in spring and summer with a balanced houseplant fertiliser at half strength. Flush the soil periodically to clear salts, and stop feeding in autumn and winter. Feed every 3-4 weeks in spring and summer with a balanced houseplant fertiliser at half strength. Flush the soil periodically to clear salts, and stop feeding in autumn and winter. For a fast grower like this that means feeding regularly — about every 3-4 weeks — right through spring through early autumn (roughly March to September), tapering off only as light drops in autumn.
What strength of feed for calathea undulata?
Half strength every feed is the sweet spot for calathea undulata: frequent enough to fuel fast growth, dilute enough that it never scorches even when you feed often.
What does over-feeding calathea undulata 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 calathea undulata?
Because you feed often, salts accumulate faster — flush the pot of calathea undulata with plain water until it drains freely roughly every month through the feeding season to keep the root zone clean.
Keep reading
- Calathea Undulata care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water calathea undulata — 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 snake plant
- How to fertilise dracaena
- How to fertilise peperomia
- All 2464 fertilising guides in the Growli library