Fertilising guide
How to fertilise Cabbage Fern (Aglaomorpha coronans)— schedule & NPK
Also called Crown Basket Fern, Basket Fern, Crowning Polypody.
More about cabbage fern
About Cabbage Fern
Aglaomorpha coronans · also called Crown Basket Fern, Basket Fern · tropical
Aglaomorpha coronans is a large epiphytic fern from tropical Asia, prized for its dramatic, deeply lobed fronds that fan out like a crown. It thrives in bright indirect light with consistently moist, well-draining growing medium and high humidity. Not listed as toxic by the ASPCA — considered pet-safe like most true ferns.
Growth habit: Large epiphytic rhizomatous fern with arching, deeply pinnate fronds
Watch for — Brown frond tips: Usually caused by low humidity, fluoride in tap water, or overfertilising. Switch to rainwater and maintain humidity above 60%.
What fertiliser cabbage fern actually wants — and why
Cabbage Fern 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 cabbage fern: 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 cabbage fern, 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 cabbage fern:
Feed with a diluted balanced liquid fertiliser (half-strength, e.g. 10-10-10) once a month during spring and summer. Avoid feeding in autumn and winter when growth slows; excess nutrients can scorch the sensitive frond tips. Treat that as once a month 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 cabbage fern 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 cabbage fern
Half strength is the safe default for cabbage fern — 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 cabbage fern first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cabbage fern watering schedule.
Signs you are over-feeding cabbage fern
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for cabbage fern:
- 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 cabbage fern
- 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 cabbage fern care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of cabbage fern 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 cabbage fern
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 cabbage fern — frequently asked questions
What fertiliser does cabbage fern 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. Cabbage Fern 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 cabbage fern?
Feed with a diluted balanced liquid fertiliser (half-strength, e.g. 10-10-10) once a month during spring and summer. Avoid feeding in autumn and winter when growth slows; excess nutrients can scorch the sensitive frond tips. Feed with a diluted balanced liquid fertiliser (half-strength, e.g. 10-10-10) once a month during spring and summer. Avoid feeding in autumn and winter when growth slows; excess nutrients can scorch the sensitive frond tips. Treat that as once a month 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 cabbage fern?
Half strength is the safe default for cabbage fern — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding cabbage fern 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 cabbage fern 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 cabbage fern?
Flush the pot of cabbage fern 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
- Cabbage Fern care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water cabbage fern — 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 nipa palm
- How to fertilise sonoran palmetto
- How to fertilise jenkins fan palm
- All 11687 fertilising guides in the Growli library