Fertilising guide
How to fertilise Slender-Leaved Sundew (Drosera linearis)— schedule & NPK
Also called slender-leaved sundew, linear-leaved sundew.
More about slender-leaved sundew
About Slender-Leaved Sundew
Drosera linearis · also called slender-leaved sundew, linear-leaved sundew · houseplant
Drosera linearis is a delicate North American temperate sundew native to cold, alkaline calcareous bogs — unusual among sundews in tolerating and even preferring limestone-influenced water with slightly higher pH. Narrow upright leaves bear glistening red mucilage glands. Requires cold dormancy and is one of the more challenging sundews for indoor cultivation.
Growth habit: Compact rosette of narrow, upright strap-like leaves densely covered in red stalked glands
What fertiliser slender-leaved sundew actually wants — and why
Slender-Leaved Sundew 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 slender-leaved sundew: 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 slender-leaved sundew, 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 slender-leaved sundew:
Feeding is achieved through insect capture on the sticky leaf glands. Supplement by placing small live or freeze-dried insects (e.g., bloodworms, fruit flies) on the leaves every 2–4 weeks during the growing season. Never apply soil fertiliser. 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 slender-leaved sundew 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 slender-leaved sundew
Half strength is the safe default for slender-leaved sundew — 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 slender-leaved sundew first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the slender-leaved sundew watering schedule.
Signs you are over-feeding slender-leaved sundew
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for slender-leaved sundew:
- 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 slender-leaved sundew
- 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 slender-leaved sundew care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of slender-leaved sundew 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 slender-leaved sundew
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 slender-leaved sundew — frequently asked questions
What fertiliser does slender-leaved sundew 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. Slender-Leaved Sundew 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 slender-leaved sundew?
Feeding is achieved through insect capture on the sticky leaf glands. Supplement by placing small live or freeze-dried insects (e.g., bloodworms, fruit flies) on the leaves every 2–4 weeks during the growing season. Never apply soil fertiliser. Feeding is achieved through insect capture on the sticky leaf glands. Supplement by placing small live or freeze-dried insects (e.g., bloodworms, fruit flies) on the leaves every 2–4 weeks during the growing season. Never apply soil fertiliser. 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 slender-leaved sundew?
Half strength is the safe default for slender-leaved sundew — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding slender-leaved sundew 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 slender-leaved sundew 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 slender-leaved sundew?
Flush the pot of slender-leaved sundew 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
- Slender-Leaved Sundew care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water slender-leaved sundew — 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 dieffenbachia memoria corsii
- How to fertilise dieffenbachia tropic marianne
- How to fertilise dieffenbachia sparkles
- All 6887 fertilising guides in the Growli library