Fertilising guide
How to fertilise Citronella Grass (Cymbopogon nardus)— schedule & NPK
Also called Citronella Grass, Nardus Grass, Sri Lanka Lemongrass.
More about citronella grass
About Citronella Grass
Cymbopogon nardus · also called Citronella Grass, Nardus Grass · herb
Citronella Grass is a large, clump-forming tropical grass native to South and Southeast Asia, grown commercially as the source of true citronella essential oil used in insect repellents and perfumery. It produces tall, graceful, blue-green arching leaves with a strong citrus-like scent when crushed. In temperate climates it is grown as a tender annual or container specimen.
Growth habit: Large, clump-forming, evergreen tropical grass; produces tall, upright then arching culms from a dense rhizomatous base
What fertiliser citronella grass actually wants — and why
Citronella Grass 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 citronella grass: 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 citronella grass, 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 citronella grass:
Feed with a balanced, nitrogen-rich fertiliser (e.g. general-purpose 10-10-10 or a grass fertiliser) monthly from spring through late summer to support rapid foliage growth. In containers, where nutrients deplete faster, a monthly liquid feed at half to full strength during the growing season is recommended. Withhold feeding entirely during winter when growth is minimal. 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 citronella grass 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 citronella grass
Half strength is a sensible default for citronella grass — 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 citronella grass first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the citronella grass watering schedule.
Signs you are over-feeding citronella grass
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for citronella grass:
- 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 citronella grass
- 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 citronella grass care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown citronella grass 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 citronella grass
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 citronella grass — frequently asked questions
What fertiliser does citronella grass 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. Citronella Grass 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 citronella grass?
Feed with a balanced, nitrogen-rich fertiliser (e.g. general-purpose 10-10-10 or a grass fertiliser) monthly from spring through late summer to support rapid foliage growth. In containers, where nutrients deplete faster, a monthly liquid feed at half to full strength during the growing season is recommended. Withhold feeding entirely during winter when growth is minimal. Feed with a balanced, nitrogen-rich fertiliser (e.g. general-purpose 10-10-10 or a grass fertiliser) monthly from spring through late summer to support rapid foliage growth. In containers, where nutrients deplete faster, a monthly liquid feed at half to full strength during the growing season is recommended. Withhold feeding entirely during winter when growth is minimal. 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 citronella grass?
Half strength is a sensible default for citronella grass — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding citronella grass 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 citronella grass 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 citronella grass?
Pot-grown citronella grass 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
- Citronella Grass care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water citronella grass — 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 rock hyssop
- How to fertilise anise
- How to fertilise black seed
- All 6887 fertilising guides in the Growli library