Fertilising guide
How to fertilise Pelargonium x asperum (Pelargonium x asperum)— schedule & NPK
Also called Rough-leaved pelargonium, Rose geranium hybrid.
More about pelargonium x asperum
About Pelargonium x asperum
Pelargonium x asperum · also called Rough-leaved pelargonium, Rose geranium hybrid · herb
Pelargonium x asperum is a rose-scented geranium grown for its aromatic, rough, deeply lobed leaves used in essential-oil distillation, baking and potpourri. A tender hybrid linked to the rose-geranium group, it bears small pink flowers and forms a bushy, sun-loving shrub. It is easy to grow in bright light with free-draining soil and modest watering.
Growth habit: Bushy, woody-based evergreen shrub with aromatic, rough-textured, lobed leaves and loose clusters of small pink flowers.
What fertiliser pelargonium x asperum actually wants — and why
Pelargonium x asperum is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.
A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed.
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 pelargonium x asperum: 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 pelargonium x asperum, 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 pelargonium x asperum:
Feed every two to four weeks through spring and summer with a balanced or high-potassium liquid feed for steady foliage and flowering. Reduce or stop in winter. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.
The dormant-season rule matters more than the exact interval: skip feeding entirely when pelargonium x asperum 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 pelargonium x asperum
Half strength is a sensible default for pelargonium x asperum — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
Feeding always goes onto already-damp soil, never dry roots — water pelargonium x asperum first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the pelargonium x asperum watering schedule.
Signs you are over-feeding pelargonium x asperum
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for pelargonium x asperum:
- Fast, soft, pale growth with diluted, less aromatic flavour.
- Early bolting (running to flower) and a bitter edge.
- Salt crust and scorched tips on container plants.
Signs you are under-feeding pelargonium x asperum
- Pale, slow regrowth after cutting and small leaves.
- A tired, stalled plant that cannot keep up with harvesting.
- Yellowing older leaves in a long-spent pot.
If the symptoms point at watering, light or roots rather than nutrition, the full pelargonium x asperum care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown pelargonium x asperum builds up feed salts quickly — water until it drains each time and flush the pot with plain water every few weeks, especially on a sunny windowsill.
Organic vs synthetic feeds for pelargonium x asperum
Organic options
A diluted seaweed feed or worm-casting tea keeps soft growth coming without overdoing it. UK: dilute seaweed or Westland; US: Espoma Garden-tone or Neptune's Harvest. Gentle, hard to overdo, flavour-friendly.
Synthetic / liquid feeds
A balanced liquid feed at half strength through harvesting — UK: Phostrogen, Baby Bio or Westland; US: Miracle-Gro all-purpose at half strength. Fast regrowth; just do not overdo the nitrogen.
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 pelargonium x asperum — frequently asked questions
What fertiliser does pelargonium x asperum need?
A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed. Pelargonium x asperum is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.
How often should I feed pelargonium x asperum?
Feed every two to four weeks through spring and summer with a balanced or high-potassium liquid feed for steady foliage and flowering. Reduce or stop in winter. Feed every two to four weeks through spring and summer with a balanced or high-potassium liquid feed for steady foliage and flowering. Reduce or stop in winter. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.
What strength of feed for pelargonium x asperum?
Half strength is a sensible default for pelargonium x asperum — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding pelargonium x asperum look like?
Fast, soft, pale growth with diluted, less aromatic flavour. Early bolting (running to flower) and a bitter edge. Salt crust and scorched tips on container plants. Over-feeding pelargonium x asperum with strong nitrogen is the usual mistake — it grows fast and lush but the leaves turn bland and it bolts to flower sooner, ending the useful harvest early.
Should I flush the soil of pelargonium x asperum?
Pot-grown pelargonium x asperum builds up feed salts quickly — water until it drains each time and flush the pot with plain water every few weeks, especially on a sunny windowsill.
Keep reading
- Pelargonium x asperum care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water pelargonium x asperum — 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 basil
- How to fertilise herb garden
- How to fertilise mint
- All 5561 fertilising guides in the Growli library