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Fertilising guide

How to fertilise Lesser Spearwort (Ranunculus flammula)— schedule & NPK

Also called Lesser Spearwort, Creeping Spearwort.

More about lesser spearwort

About Lesser Spearwort

Ranunculus flammula · also called Lesser Spearwort, Creeping Spearwort · flowering

Lesser Spearwort is a slender, creeping native European aquatic perennial found along pond margins, ditches, and bog edges. It produces small, glossy yellow buttercup flowers from late spring through summer. A good wildflower pond plant that is far less vigorous than its larger relative, Greater Spearwort. Toxic to pets and livestock if ingested.

Growth habit: Low, creeping to semi-erect slender-stemmed perennial rooting at nodes where stems touch wet soil. Forms loose, sprawling mats at the water's edge. Far less vigorous than R. lingua.

What fertiliser lesser spearwort actually wants — and why

Lesser Spearwort 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 lesser spearwort: 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 lesser spearwort, 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 lesser spearwort:

Feeding is not required or advised. Lesser Spearwort thrives in low to moderately fertile wet conditions. Adding fertiliser promotes algal competition and reduces the plant's natural vigour relative to weeds. 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 lesser spearwort 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 lesser spearwort

Half strength is the safe default for lesser spearwort — 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 lesser spearwort first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the lesser spearwort watering schedule.

Signs you are over-feeding lesser spearwort

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for lesser spearwort:

Signs you are under-feeding lesser spearwort

If the symptoms point at watering, light or roots rather than nutrition, the full lesser spearwort care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush the pot of lesser spearwort 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 lesser spearwort

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 lesser spearwort — frequently asked questions

What fertiliser does lesser spearwort 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. Lesser Spearwort 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 lesser spearwort?

Feeding is not required or advised. Lesser Spearwort thrives in low to moderately fertile wet conditions. Adding fertiliser promotes algal competition and reduces the plant's natural vigour relative to weeds. Feeding is not required or advised. Lesser Spearwort thrives in low to moderately fertile wet conditions. Adding fertiliser promotes algal competition and reduces the plant's natural vigour relative to weeds. 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 lesser spearwort?

Half strength is the safe default for lesser spearwort — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding lesser spearwort 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 lesser spearwort 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 lesser spearwort?

Flush the pot of lesser spearwort 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.

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