Fertilising guide
How to fertilise Parsley (Petroselinum crispum)— schedule & NPK
Also called flat-leaf parsley, Italian parsley, curly parsley.
About Parsley
Petroselinum crispum · also called flat-leaf parsley, Italian parsley · herb
Parsley is a biennial herb usually grown as an annual for its flavourful leaves. It is slow to germinate but otherwise undemanding, thriving in moisture-retentive soil with regular harvesting. Mildly toxic to birds and some grazing pets in large amounts.
Petroselinum crispum is a Mediterranean-native biennial in the carrot family, typically grown as an annual in cold-winter regions.
A relatively heavy-feeding herb: fertilize beds once or twice yearly (e.g. 5-10-5), and feed containers with half-strength liquid feed every 3-4 weeks.
Growth habit: Biennial rosette
Sources: extension.umn.edu, hort.extension.wisc.edu, plants.ces.ncsu.edu
What fertiliser parsley actually wants — and why
Parsley 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 parsley: 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 parsley, 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 parsley:
A balanced feed every 4 weeks during heavy harvesting. 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 parsley 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 parsley
Half strength is a sensible default for parsley — 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 parsley first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the parsley watering schedule.
Signs you are over-feeding parsley
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for parsley:
- 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 parsley
- 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 parsley care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown parsley 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 parsley
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 parsley — frequently asked questions
What fertiliser does parsley 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. Parsley 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 parsley?
A balanced feed every 4 weeks during heavy harvesting. A balanced feed every 4 weeks during heavy harvesting. 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 parsley?
Half strength is a sensible default for parsley — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding parsley 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 parsley 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 parsley?
Pot-grown parsley 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
- Parsley care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water parsley — 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 200 fertilising guides in the Growli library