Fertilising guide

How to fertilise Alpine Squill (Scilla bifolia)— schedule & NPK

Also called Alpine Squill, Two-leaved Squill.

More about alpine squill

About Alpine Squill

Scilla bifolia · also called Alpine Squill, Two-leaved Squill · flowering

Scilla bifolia is a dainty bulbous perennial native to woodland edges, alpine meadows, and rocky hillsides across central Europe, from the Alps to the Caucasus. It is one of the earliest spring bulbs to flower, producing loose racemes of starry, intense gentian-blue flowers (occasionally pink or white) in late winter to early spring before most other plants emerge. It naturalises readily under deciduous trees and in short grass. The RHS awarded it its Award of Garden Merit in 1993. All parts are toxic to cats and dogs due to cardiac glycoside compounds.

Growth habit: Small clump-forming bulbous perennial; each bulb typically produces two basal leaves and one to six flower scapes

What fertiliser alpine squill actually wants — and why

Alpine Squill feeds for next year, not this one — the critical window is after flowering, while the leaves are still green and recharging the bulb.

A low-nitrogen, potassium- and phosphorus-leaning bulb fertiliser (something like 5-10-10) or bonemeal at planting. High nitrogen grows floppy leaves and rots stored bulbs.

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 alpine squill: 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 alpine squill, 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 alpine squill:

No regular feeding needed when naturalised; in containers or poor soils, apply a low-nitrogen bulb fertiliser in early autumn as growth resumes. The rhythm: a bulb feed at planting, a light feed as leaves emerge, and — most important — a potassium feed straight after flowering while the foliage is still green and feeding the bulb. Never cut the leaves off early.

The dormant-season rule matters more than the exact interval: skip feeding entirely when alpine squill 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 alpine squill

Use the bulb-feed label rate for alpine squill; the timing (post-bloom, leaves still green) does far more for next year's display than the concentration.

Feeding always goes onto already-damp soil, never dry roots — water alpine squill first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the alpine squill watering schedule.

Signs you are over-feeding alpine squill

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

Tall, floppy, soft leaves that flop over (too much nitrogen).
Soft or rotting bulbs lifted at the end of the season.
Lush foliage but few or poor flowers.

Signs you are under-feeding alpine squill

Progressively fewer or smaller flowers year on year ("going blind").
Small, weak bulbs and thin foliage.
Bulbs that fail to come back at all after a few seasons.

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

Flushing and leaching the salts

Bulbs are not container-flushed like houseplants; the equivalent is not over-feeding and lifting/dividing congested clumps of alpine squill every few years so they are not competing for nutrients.

Organic vs synthetic feeds for alpine squill

Organic options

Bonemeal worked in at planting plus a mulch of garden compost or well-rotted leaf-mould is the traditional, reliable approach for alpine squill. UK: blood, fish & bone or Westland Bulb Food; US: Espoma Bulb-tone or bonemeal.

Synthetic / liquid feeds

A proprietary bulb fertiliser at planting and a high-potash liquid (tomato feed) after flowering — UK: Westland Bulb Food then Tomorite; US: Miracle-Gro Shake 'n Feed Bulb or a bloom booster post-flower.

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 alpine squill — frequently asked questions

What fertiliser does alpine squill need?

A low-nitrogen, potassium- and phosphorus-leaning bulb fertiliser (something like 5-10-10) or bonemeal at planting. High nitrogen grows floppy leaves and rots stored bulbs. Alpine Squill feeds for next year, not this one — the critical window is after flowering, while the leaves are still green and recharging the bulb.

How often should I feed alpine squill?

No regular feeding needed when naturalised; in containers or poor soils, apply a low-nitrogen bulb fertiliser in early autumn as growth resumes. No regular feeding needed when naturalised; in containers or poor soils, apply a low-nitrogen bulb fertiliser in early autumn as growth resumes. The rhythm: a bulb feed at planting, a light feed as leaves emerge, and — most important — a potassium feed straight after flowering while the foliage is still green and feeding the bulb. Never cut the leaves off early.

What strength of feed for alpine squill?