Fertilising guide

How to fertilise Geranium x magnificum (Geranium x magnificum)— schedule & NPK

Also called Showy cranesbill, Magnificent geranium.

More about geranium x magnificum

About Geranium x magnificum

Geranium x magnificum · also called Showy cranesbill, Magnificent geranium · flowering

Geranium x magnificum is a vigorous hardy cranesbill (a sterile hybrid of G. ibericum and G. platypetalum) grown for a single, spectacular early-summer flush of violet-blue, purple-veined flowers above deeply lobed, hairy leaves that colour red in autumn. This clump-forming perennial earns an RHS Award of Garden Merit and thrives in sun to part shade.

Growth habit: Clump-forming, spreading herbaceous perennial that forms a dense mound of foliage; a single heavy bloom flush in early to mid-summer rather than a long repeat display.

What fertiliser geranium x magnificum actually wants — and why

Geranium x magnificum 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 geranium x magnificum: 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 geranium x magnificum, 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 geranium x magnificum:

Undemanding. A single annual feed of balanced general-purpose fertiliser or a compost mulch in spring is sufficient. Avoid high-nitrogen feeds, which promote leaf at the expense of flowers and floppy stems. In practice: no routine feeding at all for geranium x magnificum — 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 geranium x magnificum 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 geranium x magnificum

None is the correct answer for geranium x magnificum. 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 geranium x magnificum first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the geranium x magnificum watering schedule.

Signs you are over-feeding geranium x magnificum

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

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 geranium x magnificum

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 geranium x magnificum care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

If geranium x magnificum 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 geranium x magnificum

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 geranium x magnificum.

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 geranium x magnificum — frequently asked questions

What fertiliser does geranium x magnificum 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. Geranium x magnificum 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 geranium x magnificum?

Undemanding. A single annual feed of balanced general-purpose fertiliser or a compost mulch in spring is sufficient. Avoid high-nitrogen feeds, which promote leaf at the expense of flowers and floppy stems. Undemanding. A single annual feed of balanced general-purpose fertiliser or a compost mulch in spring is sufficient. Avoid high-nitrogen feeds, which promote leaf at the expense of flowers and floppy stems. In practice: no routine feeding at all for geranium x magnificum — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for geranium x magnificum?