How to grow parsley — flat-leaf vs curly + biennial cycle

How to grow parsley — flat-leaf vs curly + biennial cycle

Parsley (Petroselinum crispum) is the quiet workhorse of the herb garden — used in nearly every European cuisine and a key ingredient in bouquet garni, tabbouleh, and chimichurri. It is more shade-tolerant than Mediterranean herbs and prefers moist rich soil more like a leafy vegetable than a dry-loving thyme or rosemary. The two things every new parsley grower needs to know: seeds germinate painfully slowly (soak them overnight), and the plant is a true biennial — year 1 produces leaves, year 2 produces flowers and seeds, then the plant dies.

Track your parsley sowing in Growli: Add the variety to the Growli app and you'll get reminders to soak seeds, mark the slow germination window, and plan year-2 replacement before bolting.

Parsley varieties — flat-leaf vs curly

There are two main parsley types, plus a less common root form:

Flat-leaf parsley is the standard cooking variety. Larger leaves, easier to chop, stronger flavour. Most professional kitchens use flat-leaf exclusively.

Curly parsley has tightly frilled leaves that hold their shape well as garnish but can be wiry to chew. Flavour is milder. Curly is the more cold-hardy of the two — useful in colder UK and US north gardens where flat-leaf may struggle through autumn.

Hamburg parsley is grown for its parsnip-like root rather than its leaves. Less common in UK and US gardens but useful for soup and stew.

UK retailers — variety availability

• Sarah Raven, Crocus, Hayloft stock both flat-leaf (often labelled "Italian Giant") and curly cultivars. Seed packets from Suttons, Thompson & Morgan, and Mr Fothergill's are widely available.
• Garden centres carry potted parsley transplants from April; supermarket "supermarket parsley" pots are usually overcrowded — split into 3-4 plants on planting.

US retailers — variety availability

• Burpee, Johnny's Selected Seeds, Botanical Interests carry "Italian Giant" or "Italian Plain Leaf" flat-leaf, plus "Forest Green" or "Triple Curled" for curly types.
• Renee's Garden, Seeds of Change, Hudson Valley Seed carry organic options.

Soil and sun

Parsley behaves more like a leafy vegetable than a Mediterranean herb:

• Sun: 4-6 hours direct sun. Tolerates part shade better than most herbs — useful for the shady side of a vegetable bed.
• Soil: Rich, moisture-retentive, slightly acidic to neutral (pH 6.0-7.0). Mix in compost before planting.
• Drainage: Good but not sharp — parsley likes consistent moisture, unlike rosemary or thyme.

In hot southern US summers (zones 8-10) parsley benefits from afternoon shade. In UK gardens, parsley grows happily in full sun or light shade.

Sowing from seed

Parsley seeds have a reputation for slow germination — folklore says they go to the Devil and back seven times before sprouting. The biology is real: germination is genuinely slow at 14-28 days, and erratic.

Pre-soak the seeds. This single step roughly halves germination time:

1. Place seeds in a small bowl.
2. Cover with very warm water (around 43°C / 110°F).
3. Leave overnight.
4. Pour off any seeds that float (these are non-viable).
5. Strain the rest onto a paper towel and sow immediately.

Sowing method:

1. Sow directly into the final position in spring (March-May in UK; after last frost in US), or start in 4-inch pots indoors 6-8 weeks before last frost.
2. Sow seeds 6mm (1/4 inch) deep, 2-3cm apart.
3. Keep soil consistently moist — drying out at any point in germination kills the embryo.
4. Cover with vermiculite or fine compost; many growers cover with a board for the first 7-10 days to retain moisture.
5. Germination in 14-21 days with pre-soaking; up to 28 days without.

Thin seedlings to 15-20cm apart once they have two pairs of true leaves.

Transplanting — parsley dislikes root disturbance. Either sow direct, or start in modular trays where the rootball stays intact during transplanting. Bare-root transplanting causes leaf collapse and stalls the plant for weeks.

Watering

Consistent moisture is key. Parsley is not drought-tolerant like Mediterranean herbs:

• First few weeks: Keep soil consistently damp. Drying during germination is fatal.
• Established plants: Water 2-3 times weekly during dry spells. Mulch lightly to retain moisture.
• Container parsley: Water when the top inch is dry, often daily in summer.

Wilting parsley recovers quickly if watered within an hour, but drought-stressed plants bolt to flower prematurely.

Harvesting

Parsley regrows from the centre. Harvest correctly and one plant supplies a kitchen all season:

1. Wait until the plant has at least 8-10 stems with full leaves.
2. Cut outer stems at the base (just above the soil), leaving the central new growth untouched.
3. Take no more than a third of the plant in one harvest.
4. Repeat every 2-3 weeks during the growing season.

Never just pick leaves off stems — the stem itself stops producing once topped. Always cut whole outer stems at ground level.

For storage, freshly cut parsley keeps 7-10 days in a glass of water in the fridge. For longer storage, freeze chopped parsley in ice cube trays with water or olive oil.

The biennial cycle

Parsley is a true biennial: year 1 it produces leaves, year 2 it produces flowers, seeds, and dies. This matters in two ways:

Practical: The best leaf quality is year 1. Year-2 leaves become bitter and tough as the plant prepares to flower. The plant bolts (sends up a flower stalk) in late spring or early summer of year 2, after which it stops producing usable leaves entirely.

Strategy: Sow fresh parsley every spring. Pull or compost year-2 plants once they bolt, unless you specifically want to save seed (let one plant flower and dry; collect seeds in late summer).

In cold climates (USDA zones 3-5, northern UK), parsley often does not survive its first winter and is grown as an annual. In mild climates (zones 7+, southern UK) it reliably overwinters and bolts in spring.

Winter care

Parsley is more cold-tolerant than basil or rosemary:

• In-ground plants — survive to about -12°C / 10°F. Mulch with straw or shredded leaves for protection in zones 4-5.
• Container plants — move to a sheltered spot or unheated greenhouse over winter. They survive but stop active growth.
• Indoor parsley — bring a small pot inside in October. Place on a bright windowsill; grow lights extend harvest through midwinter.

Year-1 plants kept alive through winter will bolt in spring of year 2 — plan to replace them after the spring flower stalk appears.

Pests and problems

Parsley is moderately pest-resistant. Watch for:

• Carrot fly (UK common, US uncommon) — larvae tunnel into stems. Cover with fine mesh from sowing.
• Aphids on new growth — squash by hand or spray with water. See aphids on plants.
• Slugs and snails — especially on young seedlings. See garden pest identification for management.
• Swallowtail butterfly caterpillars (US) — large green caterpillars with black bands. Pretty butterflies; consider relocating rather than killing.
• Bolting in hot weather — premature flowering reduces leaf quality. Water consistently and mulch to keep roots cool.

Pet safety — parsley and pets

The ASPCA classifies parsley (Petroselinum crispum) as toxic to dogs, cats, and horses. The toxic principle is furanocoumarins, which can cause photosensitisation (sunburn, dermatitis, blisters on light-coloured skin) when pets ingest large amounts and are then exposed to sunlight.

For practical purposes: a pet nibbling a few parsley leaves is a low risk. Cooking-quantity parsley sprinkled in pet food is generally considered safe in moderation, though some vets recommend avoiding it entirely. Avoid pets ingesting large quantities — particularly the spring parsley (Cymopterus watsonii) often confused with culinary parsley, which is significantly more dangerous.

If a pet ingests an unusually large amount and shows photosensitivity symptoms (skin redness, blistering), call the ASPCA Animal Poison Control Center at (888) 426-4435 or your vet.

Companion planting

Parsley is a useful companion for:

• Tomatoes — improves vigour and may repel some aphid species.
• Asparagus — long-standing pairing in vegetable gardens; both are perennial and don't compete for the same root zone.
• Carrots — flowering parsley in year 2 attracts parasitic wasps that prey on carrot fly.
• Roses — interplanting parsley around rose bushes has been used as an aphid deterrent.

Avoid planting parsley near:

• Mint — mint will out-compete parsley within a season.
• Lettuce — both compete for the same shallow root zone and water.
• Onions and garlic (in tight spacing) — they slow parsley growth in close proximity.

Letting one parsley plant flower in year 2 (rather than pulling immediately) provides a major boost to beneficial insect populations — parasitic wasps, hoverflies, and lacewings feed on parsley umbels and then prey on aphids and caterpillars in the rest of the garden.

Culinary use

Parsley is one of the most versatile cooking herbs:

• Flat-leaf: Tabbouleh, chimichurri, gremolata, pesto-style sauces, finishing fresh on roast vegetables and grilled meats.
• Curly: Traditional garnish, deep-fried as crisp garnish, sauce verte.
• Stems: Don't discard — chop finely for stocks, soups, and slow-cooked dishes.

Parsley loses flavour when dried. For storage, freeze chopped leaves rather than drying.

Related articles

• How to grow basil — the warm-season companion
• How to grow chives — another moisture-loving herb
• How to grow mint — similar moisture preference
• Types of herbs — Mediterranean vs moisture-loving vs annual
• Companion planting guide — parsley pairings

Reviewed and updated by the Growli editorial team. Pet-safety claims sourced from the ASPCA Animal Poison Control Center. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.