Fertilising guide
How to fertilise Arrow Arum (Peltandra virginica)— schedule & NPK
Also called Arrow Arum, Green Arrow Arum, Tuckahoe, Virginia Peltandra.
More about arrow arum
About Arrow Arum
Peltandra virginica · also called Arrow Arum, Green Arrow Arum · flowering
Peltandra virginica is a robust aquatic and emergent wetland perennial native to swamps, marshes, and slow-moving streams along the eastern coast of North America. It thrives in shallow standing water or permanently waterlogged boggy soil in full sun to part shade, producing distinctive glossy, arrow-shaped leaves up to 45 cm long and a green-spathed flower spike followed by green berry clusters. The single most important care fact is providing permanent wet feet — it must grow in consistently flooded or saturated soil. This plant is toxic to cats and dogs due to calcium oxalate crystals in all plant parts.
Growth habit: Clump-forming emergent aquatic perennial spreading by short rhizomes; forms expanding colonies in suitable wet conditions but is not aggressively invasive.
What fertiliser arrow arum actually wants — and why
Arrow Arum 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 arrow arum: 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 arrow arum, 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 arrow arum:
Apply a slow-release aquatic fertiliser tablet pushed into the root zone once in spring; avoid releasing excess nutrients into the water column which can cause algal blooms. Treat that as sparingly through the growing season 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 arrow arum 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 arrow arum
Half strength is the safe default for arrow arum — 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 arrow arum first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the arrow arum watering schedule.
Signs you are over-feeding arrow arum
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for arrow arum:
- 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 arrow arum
- 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 arrow arum care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of arrow arum 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 arrow arum
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 arrow arum — frequently asked questions
What fertiliser does arrow arum 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. Arrow Arum 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 arrow arum?
Apply a slow-release aquatic fertiliser tablet pushed into the root zone once in spring; avoid releasing excess nutrients into the water column which can cause algal blooms. Apply a slow-release aquatic fertiliser tablet pushed into the root zone once in spring; avoid releasing excess nutrients into the water column which can cause algal blooms. Treat that as sparingly through the growing season 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 arrow arum?
Half strength is the safe default for arrow arum — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding arrow arum 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 arrow arum 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 arrow arum?
Flush the pot of arrow arum 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
- Arrow Arum care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water arrow arum — 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 siskiyou lewisia
- How to fertilise nevada lewisia
- How to fertilise short-sepalled lewisia
- All 10153 fertilising guides in the Growli library