Fertilising guide

How to fertilise Red Campion (Silene dioica)— schedule & NPK

Also called Red Campion, Red Catchfly, Bachelor's Buttons.

More about red campion

About Red Campion

Silene dioica · also called Red Campion, Red Catchfly · flowering

Silene dioica is a short-lived dioecious perennial or biennial native to woodland edges, hedgerows, and shaded banks across the UK and Europe. It bears vivid rose-pink flowers from late spring through summer and self-seeds freely, maintaining colonies without intervention. The most important care fact is to allow self-seeding or to sow fresh seed each year, as individual plants are relatively short-lived. The plant contains saponins; while not acutely dangerous to cats or dogs in typical garden exposure, it should be treated as mildly toxic as it is not listed on the ASPCA database.

Growth habit: Upright, clump-forming short-lived perennial or biennial with softly hairy foliage and branching stems bearing five deeply notched petals.

What fertiliser red campion actually wants — and why

Red Campion flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.

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 red campion: 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 red campion, 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 red campion:

Apply a balanced general fertiliser in spring only if soil is very poor; over-feeding produces rank leafy growth at the expense of flowers. In practice: no routine feeding at all for red campion — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

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

None is the correct answer for red campion. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.

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

Signs you are over-feeding red campion

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

Abundant leafy growth and very few flowers (the classic over-rich symptom).
Soft, floppy stems and a sprawling, leafy habit.
Scorched edges and salt crust if it has been fed in a container.

Signs you are under-feeding red campion

Effectively never an issue — these plants flower on poverty.
Only on genuinely dead soil: weak, thin growth and few blooms.
A short-lived plant in completely spent container compost.

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

Flushing and leaching the salts

If red campion has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.

Organic vs synthetic feeds for red campion

Organic options

A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.

Synthetic / liquid feeds

None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in red campion.

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 red campion — frequently asked questions

What fertiliser does red campion need?

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Red Campion flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

How often should I feed red campion?

Apply a balanced general fertiliser in spring only if soil is very poor; over-feeding produces rank leafy growth at the expense of flowers. Apply a balanced general fertiliser in spring only if soil is very poor; over-feeding produces rank leafy growth at the expense of flowers. In practice: no routine feeding at all for red campion — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for red campion?