Fertilising guide
How to fertilise Liquorice (Glycyrrhiza glabra)— schedule & NPK
Also called Liquorice, Licorice, Sweet Root, Common Liquorice.
More about liquorice
About Liquorice
Glycyrrhiza glabra · also called Liquorice, Licorice · herb
Liquorice is a deep-rooted perennial legume native to the Mediterranean and southwestern Asia, cultivated for its thick, sweet taproot which contains glycyrrhizin — up to 50 times sweeter than sucrose. It requires a long, warm growing season, deep well-drained soil, and full sun. Roots are typically harvested after 3–4 years for culinary and medicinal use.
Growth habit: Clump-forming, spreading perennial with pinnate leaves on arching stems. Spreads by runners (stolons) and can colonise a wide area. Produces small pale-blue to violet pea-like flowers in summer but is rarely a prolific bloomer in cool climates.
What fertiliser liquorice actually wants — and why
Liquorice 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 liquorice: 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 liquorice, 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 liquorice:
Apply a balanced granular fertiliser (10-10-10) in early spring as growth resumes. Liquorice is a nitrogen-fixing legume, so supplemental nitrogen is minimal; focus on phosphorus and potassium to support root development. Avoid high-nitrogen feeds which promote leafy growth at the expense of root yield. 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 liquorice 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 liquorice
Half strength is a sensible default for liquorice — 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 liquorice first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the liquorice watering schedule.
Signs you are over-feeding liquorice
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for liquorice:
- 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 liquorice
- 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 liquorice care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown liquorice 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 liquorice
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 liquorice — frequently asked questions
What fertiliser does liquorice 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. Liquorice 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 liquorice?
Apply a balanced granular fertiliser (10-10-10) in early spring as growth resumes. Liquorice is a nitrogen-fixing legume, so supplemental nitrogen is minimal; focus on phosphorus and potassium to support root development. Avoid high-nitrogen feeds which promote leafy growth at the expense of root yield. Apply a balanced granular fertiliser (10-10-10) in early spring as growth resumes. Liquorice is a nitrogen-fixing legume, so supplemental nitrogen is minimal; focus on phosphorus and potassium to support root development. Avoid high-nitrogen feeds which promote leafy growth at the expense of root yield. 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 liquorice?
Half strength is a sensible default for liquorice — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding liquorice 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 liquorice 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 liquorice?
Pot-grown liquorice 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
- Liquorice care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water liquorice — 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 spanish marjoram
- How to fertilise corn mint
- How to fertilise horse mint
- All 8452 fertilising guides in the Growli library