How to Grow Flat Leaf Parsley from Seed: A Complete Guide to Planting, Varieties & Care

Intro for growing flat leaf parsley from seed

Flat leaf parsley (Petroselinum crispum var. neapolitanum) is a versatile, nutrient-rich herb that adds fresh flavor to countless dishes. Unlike its curly cousin, flat leaf parsley offers a more robust flavor profile that professional chefs prefer. This biennial herb grows well in most temperate climates, thriving in both garden beds and containers. With its deep green leaves packed with vitamins A, C, and K, flat leaf parsley is not only a culinary staple but also provides ornamental value with its attractive foliage. Growing flat leaf parsley from seed is economical and rewarding, allowing you to enjoy continuous harvests throughout the growing season with minimal effort.

When to plant flat leaf parsley from seed

Flat leaf parsley seeds germinate best when soil temperatures range between 10-24°C (50-75°F). In most temperate regions, parsley can be started indoors 10-12 weeks before the last spring frost, or direct-sown once soil has warmed in spring. Parsley is frost-tolerant once established, handling light frosts down to -7°C (20°F). In Mediterranean or warm climates (US Zones 9-10), parsley can be sown in autumn for winter growth. For cooler regions (US Zones 4-6), start seeds indoors in late winter, as parsley’s slow germination requires patience during colder months.

Best time to plant flat leaf parsley from seed

For cool-temperate regions (UK, Northern US, Canada), start seeds indoors February to March, or direct sow April to June once soil temperatures consistently reach 10°C (50°F). For warm-temperate regions (Southern US, Mediterranean), direct sow September to November for winter growth, or February to April for spring/summer growth. Transplant indoor-started seedlings outdoors when they have 2-3 true leaves, typically 3-4 weeks after germination. For continuous harvests, succession plant every 3-4 weeks during the growing season, pausing during the hottest summer months in warm regions.

Best flat leaf parsley varieties to grow

• Italian Giant – Large, deeply-flavored leaves on sturdy stems, excellent for cooking and drying.
• Titan – Heat-tolerant variety with exceptional bolt resistance, perfect for warmer climates.
• Plain Leaf – Classic variety with excellent flavor and reliable growth in most conditions.
• Giant of Italy – Enormous leaves with intense flavor, ideal for pesto and cooking.
• Flat Leaf – Compact growth habit making it perfect for containers and small spaces.
• Hamburg – Dual-purpose variety grown for both its leaves and its parsnip-like root.
• Japanese Flat Leaf – Excellent cold tolerance with a distinctive, robust flavor profile.

How to plant flat leaf parsley from seed

Materials needed:

• Flat leaf parsley seeds
• Seed starting mix or well-draining potting soil
• Seed trays or small pots (for indoor starting)
• Spray bottle for gentle watering
• Clear plastic cover or plastic wrap (optional)
• Garden fork or tiller (for outdoor planting)
• Compost or aged manure

Step-by-step planting:

1. Prepare seeds by soaking in warm water for 24 hours to speed germination (optional but helpful).
2. For indoor starting, fill seed trays with moistened seed starting mix.
3. Sow seeds 6mm (¼ inch) deep, spacing them 2.5cm (1 inch) apart in trays.
4. For direct sowing, prepare garden soil by incorporating compost and breaking up clumps.
5. Create shallow furrows 6mm (¼ inch) deep, spaced 30cm (12 inches) apart.
6. Sow seeds thinly along furrows and cover lightly with soil.
7. Water gently but thoroughly using a fine spray to avoid displacing seeds.
8. For indoor seeds, cover trays with plastic to maintain humidity until germination.
9. Place in a warm location (18-21°C/65-70°F) until germination, which takes 14-28 days.
10. Once seedlings emerge, remove covers and place in bright light.

How to grow flat leaf parsley from seed

Flat leaf parsley thrives in partial to full sun, requiring at least 6 hours of sunlight daily for optimal growth. In hot climates, afternoon shade is beneficial. Water consistently to maintain evenly moist soil, providing about 2.5cm (1 inch) of water weekly, adjusting for rainfall. Avoid overhead watering to prevent disease. Fertilize lightly every 4-6 weeks with a balanced organic fertilizer or compost tea. Apply a thin layer of mulch around plants to retain moisture and suppress weeds, keeping it away from stems to prevent rot.

When growing in containers, use pots at least 20cm (8 inches) deep with drainage holes. Container-grown parsley requires more frequent watering, sometimes daily during hot weather. Thin seedlings to 15-20cm (6-8 inches) apart when they reach 5cm (2 inches) tall, using the thinnings in cooking. Parsley doesn’t require staking but benefits from light harvesting to encourage bushier growth. In containers, rotate plants regularly to ensure even growth and light exposure.

Caring for flat leaf parsley from seed

Monitor soil moisture regularly, especially during dry spells. Remove yellowing leaves promptly to prevent disease spread. Watch for aphids, which can be controlled with a strong water spray or insecticidal soap. Leaf spot diseases appear as dark spots on foliage and can be prevented by avoiding overhead watering and ensuring good air circulation. Powdery mildew, appearing as white powder on leaves, can be treated with a baking soda spray (1 tablespoon baking soda, 1 teaspoon mild liquid soap, 1 gallon water).

Begin harvesting when plants reach 15cm (6 inches) tall, taking outer stems first and cutting close to the base. Morning harvesting provides the highest concentration of essential oils for best flavor. For storage, wrap unwashed stems in damp paper towels and refrigerate for up to one week, or freeze chopped leaves in ice cube trays with water or oil for longer preservation.

Understanding bolting in flat leaf parsley

Bolting is when parsley shifts from leaf production to flowering and seed production, resulting in a tall central stem, reduced leaf growth, and bitter flavor. As a biennial, parsley naturally bolts in its second year, but can bolt prematurely due to heat stress (temperatures consistently above 26°C/80°F), drought, or long daylight hours. Prevent premature bolting by planting in partial shade in hot climates, maintaining consistent moisture, and selecting bolt-resistant varieties like ‘Titan’.

If bolting begins, you can extend harvest by promptly removing flower stalks as they appear. Once fully bolted, the leaves become bitter, but you can allow some plants to flower to attract beneficial insects and collect seeds for next season. Consider succession planting new parsley every few months during the growing season to ensure continuous harvest.

Why does flat leaf parsley turn bitter?

• Bolting: Once parsley begins flowering, leaves develop a bitter taste – harvest regularly and remove flower stalks.
• Heat stress: Excessive heat causes bitterness – provide afternoon shade in hot climates.
• Age: Older leaves naturally become more bitter – harvest younger leaves for milder flavor.
• Drought: Water stress increases bitter compounds – maintain consistent soil moisture.
• Nutrient imbalance: Excessive nitrogen fertilizer can cause bitterness – use balanced, organic fertilizers.

Companion planting for flat leaf parsley

Flat leaf parsley makes an excellent companion for numerous garden plants. Plant near tomatoes to repel certain pests and potentially improve tomato flavor. Roses benefit from parsley’s ability to attract beneficial insects that prey on rose pests. Asparagus grows well with parsley as they don’t compete for nutrients. Corn and parsley form a beneficial relationship, with parsley helping to deter some corn pests. Carrots and parsley, despite being relatives, grow well together with parsley attracting predatory insects that control carrot fly.

Avoid planting parsley near lettuce, as they can inhibit each other’s growth. Also keep parsley away from mint, which tends to be invasive and can overwhelm parsley plants.

Seasonal calendar

• January-February: Start seeds indoors in cold regions; plan garden layout.
• March-April: Direct sow in mild regions; transplant indoor seedlings after last frost.
• May-June: Continue succession planting; begin regular harvesting of established plants.
• July-August: Provide shade in hot regions; maintain consistent watering; harvest regularly.
• September-October: Direct sow fall crop in warm regions; harvest and preserve before frost in cold regions.
• November-December: Protect plants from hard freezes in marginal zones; continue harvesting in mild climates.

Problems & solutions

Common questions about growing flat leaf parsley from seed

How often should I water parsley seedlings?
Keep soil consistently moist but not waterlogged. For seedlings, water when the top 1cm (½ inch) of soil feels dry. Established plants need about 2.5cm (1 inch) of water weekly from rainfall or irrigation.

How much sun does flat leaf parsley need?
Flat leaf parsley grows best with 6-8 hours of sunlight daily. In hot climates (zones 8+), afternoon shade is beneficial to prevent stress and premature bolting.

What size container works for growing parsley?
Use containers at least 20cm (8 inches) deep and 20cm (8 inches) in diameter. Each plant needs about 20cm (8 inches) of space, so a 30cm (12-inch) pot can accommodate 2-3 plants.

How far apart should I space parsley plants?
Space plants 15-20cm (6-8 inches) apart in rows 30cm (12 inches) apart. In containers, allow 20cm (8 inches) between plants for adequate growth.

Can parsley survive frost?
Established parsley plants can tolerate light frosts down to -7°C (20°F). In colder regions, protect plants with row covers or cold frames to extend the harvest season.

How often can I harvest parsley without harming the plant?
Harvest up to one-third of the plant at once, allowing it to regrow before harvesting again. With proper care, you can harvest every 3-4 weeks throughout the growing season.

Why are my parsley seeds taking so long to germinate?
Parsley is notoriously slow to germinate, taking 14-28 days. Speed germination by soaking seeds for 24 hours before planting and maintaining soil temperature around 21°C (70°F).