Fertilising guide
How to fertilise Kaffir Lime (Citrus hystrix)— schedule & NPK
Also called kaffir lime, makrut lime, Thai lime.
More about kaffir lime
About Kaffir Lime
Citrus hystrix · also called kaffir lime, makrut lime · herb
Makrut lime is a small, thorny citrus tree grown chiefly for its intensely aromatic, double-lobed leaves, an essential flavouring in Thai, Cambodian, and Indonesian cooking, and for its bumpy, fragrant fruit zest. Tender and frost-sensitive, it is widely grown in containers and brought indoors over winter in cool climates, rewarding warmth, bright light, and steady moisture.
Growth habit: Small, densely branched, thorny evergreen shrub or tree with distinctive glossy, hourglass-shaped double leaves and knobbly green fruit.
Watch for — Nutrient deficiency (yellowing leaves): Interveinal yellowing signals iron, magnesium, or nitrogen shortfall common in container citrus. Feed with a balanced citrus fertiliser containing micronutrients through the growing season.
What fertiliser kaffir lime actually wants — and why
Kaffir Lime 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 kaffir lime: 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 kaffir lime, 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 kaffir lime:
Feed regularly through the growing season with a dedicated citrus fertiliser, typically a high-nitrogen summer formula switched to a winter citrus feed in the cooler months; citrus are hungry and prone to nutrient deficiencies if underfed. 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 kaffir lime 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 kaffir lime
Half strength is a sensible default for kaffir lime — 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 kaffir lime first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the kaffir lime watering schedule.
Signs you are over-feeding kaffir lime
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for kaffir lime:
- 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 kaffir lime
- 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 kaffir lime care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown kaffir lime 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 kaffir lime
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 kaffir lime — frequently asked questions
What fertiliser does kaffir lime 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. Kaffir Lime 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 kaffir lime?
Feed regularly through the growing season with a dedicated citrus fertiliser, typically a high-nitrogen summer formula switched to a winter citrus feed in the cooler months; citrus are hungry and prone to nutrient deficiencies if underfed. Feed regularly through the growing season with a dedicated citrus fertiliser, typically a high-nitrogen summer formula switched to a winter citrus feed in the cooler months; citrus are hungry and prone to nutrient deficiencies if underfed. 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 kaffir lime?
Half strength is a sensible default for kaffir lime — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding kaffir lime 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 kaffir lime 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 kaffir lime?
Pot-grown kaffir lime 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
- Kaffir Lime care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water kaffir lime — 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 2464 fertilising guides in the Growli library