Fertilising guide
How to fertilise Drosera Filiformis (Drosera filiformis)— schedule & NPK
Also called thread-leaved sundew, filiform sundew.
More about drosera filiformis
About Drosera Filiformis
Drosera filiformis · also called thread-leaved sundew, filiform sundew · houseplant
Drosera filiformis, the thread-leaved sundew, is a temperate North American carnivore with erect, thread-like leaves up to 25 cm tall, entirely coated in glistening sticky tentacles that trap and curl around insects. A bog plant of the US eastern seaboard, it needs full sun, permanently wet soft soil, and a cold winter dormancy in which it dies back to a hibernaculum bud.
Growth habit: Erect, temperate rosette-forming carnivorous perennial; tall thread-like dewy leaves rise from a central crown and die back each winter to a tight hibernaculum (resting bud).
Watch for — Slow decline and loss of dew: Hard tap water or fertiliser contamination. Switch to rain/distilled water, flush the medium, and repot into fresh peat-sand mix.
What fertiliser drosera filiformis actually wants — and why
Drosera Filiformis 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 drosera filiformis: 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 drosera filiformis, 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 drosera filiformis:
None at the roots. It catches its own insects on the sticky leaves; in a bug-free room, offer occasional tiny insects or rehydrated bloodworms on the dew. Root fertiliser will kill it. 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 drosera filiformis 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 drosera filiformis
Half strength is the safe default for drosera filiformis — 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 drosera filiformis first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the drosera filiformis watering schedule.
Signs you are over-feeding drosera filiformis
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for drosera filiformis:
- 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 drosera filiformis
- 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 drosera filiformis care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of drosera filiformis 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 drosera filiformis
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 drosera filiformis — frequently asked questions
What fertiliser does drosera filiformis 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. Drosera Filiformis 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 drosera filiformis?
None at the roots. It catches its own insects on the sticky leaves; in a bug-free room, offer occasional tiny insects or rehydrated bloodworms on the dew. Root fertiliser will kill it. None at the roots. It catches its own insects on the sticky leaves; in a bug-free room, offer occasional tiny insects or rehydrated bloodworms on the dew. Root fertiliser will kill it. 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 drosera filiformis?
Half strength is the safe default for drosera filiformis — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding drosera filiformis 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 drosera filiformis 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 drosera filiformis?
Flush the pot of drosera filiformis 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
- Drosera Filiformis care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water drosera filiformis — 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