Fertilising guide
How to fertilise Sea Mouse-ear (Cerastium diffusum)— schedule & NPK
Also called Sea Mouse-ear, Four-stamened Chickweed.
More about sea mouse-ear
About Sea Mouse-ear
Cerastium diffusum · also called Sea Mouse-ear, Four-stamened Chickweed · flowering
Cerastium diffusum is a slender, sticky-hairy annual native to coastal dunes, sandy cliffs, and dry grasslands along the Atlantic coasts of western Europe, including the British Isles. It prefers open, free-draining sandy or gravelly soils in full sun, flowering from March to June with tiny white, deeply notched petals. Its most important care trait is excellent drainage and low soil fertility — enriched or compacted soils cause it to decline rapidly. This species is not listed by the ASPCA; it is an obscure wild annual with no reported toxicity, but classify as mildly-toxic due to absence of confirmation.
Growth habit: Low, spreading annual, 5–25 cm tall, with slender, sticky-glandular stems and small, oval, grey-green leaves arranged in opposite pairs.
What fertiliser sea mouse-ear actually wants — and why
Sea Mouse-ear 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 sea mouse-ear: 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 sea mouse-ear, 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 sea mouse-ear:
No feeding required or recommended; this plant is naturally adapted to infertile soils and responds negatively to nutrient enrichment. 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 sea mouse-ear 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 sea mouse-ear
Half strength is the safe default for sea mouse-ear — 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 sea mouse-ear first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the sea mouse-ear watering schedule.
Signs you are over-feeding sea mouse-ear
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for sea mouse-ear:
- 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 sea mouse-ear
- 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 sea mouse-ear care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of sea mouse-ear 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 sea mouse-ear
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 sea mouse-ear — frequently asked questions
What fertiliser does sea mouse-ear 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. Sea Mouse-ear 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 sea mouse-ear?
No feeding required or recommended; this plant is naturally adapted to infertile soils and responds negatively to nutrient enrichment. No feeding required or recommended; this plant is naturally adapted to infertile soils and responds negatively to nutrient enrichment. 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 sea mouse-ear?
Half strength is the safe default for sea mouse-ear — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding sea mouse-ear 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 sea mouse-ear 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 sea mouse-ear?
Flush the pot of sea mouse-ear 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
- Sea Mouse-ear care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water sea mouse-ear — 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 zulu spurflower
- How to fertilise double-flowered bloodroot
- How to fertilise virginia spring beauty
- All 10153 fertilising guides in the Growli library