Fertilising guide
How to fertilise Wendt's Water Trumpet (Cryptocoryne wendtii)— schedule & NPK
Also called Wendt's Crypt, Water Trumpet, Crypt Wendtii.
More about wendt's water trumpet
About Wendt's Water Trumpet
Cryptocoryne wendtii · also called Wendt's Crypt, Water Trumpet · tropical
Cryptocoryne wendtii is a Sri Lankan aquatic aroid widely grown as an aquarium plant or in marginal pond settings. It produces broad, lance-shaped leaves ranging from green to bronze-brown. Keep submerged or in saturated substrate with stable low-to-medium light. Toxic to pets due to calcium oxalates common to all Araceae.
Growth habit: Rosette-forming aquatic or semi-aquatic perennial
Watch for — Algae overgrowth: Too much light or excess nutrients encourages algae on leaves. Reduce light intensity or duration, and introduce algae-eating tank inhabitants if used in an aquarium.
What fertiliser wendt's water trumpet actually wants — and why
Wendt's Water Trumpet 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 wendt's water trumpet: 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 wendt's water trumpet, 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 wendt's water trumpet:
Apply aquatic root tabs or liquid aquarium fertiliser monthly during the growing season (spring–autumn). Avoid high-phosphate formulas that promote algae; a balanced NPK with micronutrients supports healthy leaf development. Treat that as monthly 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 wendt's water trumpet 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 wendt's water trumpet
Half strength is the safe default for wendt's water trumpet — 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 wendt's water trumpet first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the wendt's water trumpet watering schedule.
Signs you are over-feeding wendt's water trumpet
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for wendt's water trumpet:
- 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 wendt's water trumpet
- 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 wendt's water trumpet care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of wendt's water trumpet 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 wendt's water trumpet
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 wendt's water trumpet — frequently asked questions
What fertiliser does wendt's water trumpet 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. Wendt's Water Trumpet 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 wendt's water trumpet?
Apply aquatic root tabs or liquid aquarium fertiliser monthly during the growing season (spring–autumn). Avoid high-phosphate formulas that promote algae; a balanced NPK with micronutrients supports healthy leaf development. Apply aquatic root tabs or liquid aquarium fertiliser monthly during the growing season (spring–autumn). Avoid high-phosphate formulas that promote algae; a balanced NPK with micronutrients supports healthy leaf development. Treat that as monthly 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 wendt's water trumpet?
Half strength is the safe default for wendt's water trumpet — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding wendt's water trumpet 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 wendt's water trumpet 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 wendt's water trumpet?
Flush the pot of wendt's water trumpet 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
- Wendt's Water Trumpet care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water wendt's water trumpet — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
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- How to fertilise ruellia devosiana
- All 11687 fertilising guides in the Growli library