Fertilising guide
How to fertilise Lemon Basil (Ocimum × africanum 'Mrs. Burns')— schedule & NPK
Also called Mrs. Burns Lemon Basil.
More about lemon basil
About Lemon Basil
Ocimum × africanum 'Mrs. Burns' · also called Mrs. Burns Lemon Basil · herb
Lemon basil is a citrus-scented hybrid basil whose leaves carry a bright lemon aroma from high citral content, prized in Thai and Southeast Asian cooking. 'Mrs. Burns' is a vigorous heirloom strain with larger leaves and strong fragrance. Grow it as a tender warm-season annual in full sun, pinching often to delay its quick flowering.
Growth habit: Upright, fast-growing and quick to flower, with narrower pale-green leaves than sweet basil. Frequent pinching keeps it bushy and productive.
Watch for — Loss of aroma: Low light or over-fertilising weakens the lemon scent. Maximise sun and feed sparingly to keep the citral high.
What fertiliser lemon basil actually wants — and why
Lemon Basil 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 lemon basil: 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 lemon basil, 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 lemon basil:
Feed every 3-4 weeks with a balanced liquid fertiliser at half strength during growth. Moderate feeding keeps the citral aroma concentrated; overdoing nitrogen produces bland, lush leaves. 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 lemon basil 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 lemon basil
Half strength is a sensible default for lemon basil — 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 lemon basil first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the lemon basil watering schedule.
Signs you are over-feeding lemon basil
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for lemon basil:
- 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 lemon basil
- 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 lemon basil care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown lemon basil 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 lemon basil
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 lemon basil — frequently asked questions
What fertiliser does lemon basil 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. Lemon Basil 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 lemon basil?
Feed every 3-4 weeks with a balanced liquid fertiliser at half strength during growth. Moderate feeding keeps the citral aroma concentrated; overdoing nitrogen produces bland, lush leaves. Feed every 3-4 weeks with a balanced liquid fertiliser at half strength during growth. Moderate feeding keeps the citral aroma concentrated; overdoing nitrogen produces bland, lush leaves. 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 lemon basil?
Half strength is a sensible default for lemon basil — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding lemon basil 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 lemon basil 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 lemon basil?
Pot-grown lemon basil 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
- Lemon Basil care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water lemon basil — 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 1284 fertilising guides in the Growli library