How to Sow Crunchy Spring Onion Seeds  

Crunchy spring onions, also known as scallions, green onions, or white Lisbon, are a versatile and easy-to-grow vegetable. Recognisable by their fleshy white bulbs and light green stems, they offer a mild flavour compared to traditional onions. Widely used in UK kitchens, they pair well with dishes such as teriyaki and ricotta-based recipes. Perfect for growing in gardens, allotments, or even pots and containers, spring onions are a rewarding addition to any homegrown vegetable collection. 

When to Sow Crunchy Spring Onion Seeds 

• Indoor Sowing: Start seeds indoors from late winter to early spring (February to April) for an early harvest. Spring onions grow well in pots, containers, or window boxes placed in a warm, sunny location.
• Outdoor Sowing: Sow seeds directly outdoors from late spring (April to June) after the last frost has passed and the ground is workable. Spring onions can also be sown in late summer (August) for an autumn crop. 

Step-by-Step Guide to Sowing Crunchy Spring Onion Seeds 

Indoor Sowing 

1. Prepare Containers: Fill pots or seed trays with high-quality, well-draining seed compost. Choose containers with drainage holes to prevent waterlogging. 
2. Sowing the Seeds: Sow seeds at a depth of 1/2 inch (1.25 cm). Cover lightly with compost and water gently to settle the soil. 
3. Germination Conditions: Place the containers in a warm area with plenty of light, such as a sunny windowsill. Maintain a consistent temperature of 15-20°C (59-68°F). Spring onion seeds typically germinate within 10 to 14 days. 
4. Care After Germination: Keep the compost moist but not soggy. Thin seedlings if they become overcrowded, spacing them about 2 inches apart. 

Outdoor Sowing 

1. Soil Preparation: Choose a sunny spot with well-drained, fertile soil. Prepare the soil by loosening it with a fork and removing weeds. Adding a small amount of compost or well-rotted manure will improve fertility. 
2. Sowing the Seeds: Sow seeds directly into the soil at a depth of 1/2 inch (1.25 cm). Space seeds about 2 inches apart, either in clusters or along rows. If sowing in rows, maintain a row spacing of 12 to 18 inches. 
3. Watering: Gently water the area after sowing to settle the soil. Keep the soil consistently moist during germination and early growth. 
4. Thinning Seedlings: Thin seedlings to 2 inches apart once they emerge to allow enough space for the plants to mature. 

Caring for Crunchy Spring Onion Plants 

1. Watering: Keep the soil evenly moist, especially during dry spells. Avoid waterlogging, as overly wet conditions can hinder growth. 
2. Sunlight: Spring onions thrive in full sun but can tolerate partial shade. Ensure they receive at least 6 hours of sunlight daily for optimal growth. 
3. Feeding: Apply a general-purpose fertiliser once during the growing season to encourage healthy, vigorous plants. 
4. Mulching: Adding a thin layer of mulch around the base of the plants helps retain soil moisture and suppress weeds. 

Harvesting Crunchy Spring Onions 

• Harvest Time: Spring onions can be harvested between 60 and 120 days after sowing, depending on the desired size and flavour intensity. For milder onions, harvest earlier; for a stronger taste, wait longer. 
• How to Harvest: Pull up the onions gently, ensuring the bulbs remain intact. For continuous harvests, sow seeds every few weeks during the growing season. 
• Transplanting Seedlings: If growing indoors and transplanting outdoors, wait until seedlings are about 10 weeks old. Clip the plants to 3 inches tall before planting them in their final growing position at a depth of 2 inches. 

Common Questions About Growing Crunchy Spring Onions in the UK 

• Can I grow spring onions indoors year-round? Yes, spring onions can be grown indoors throughout the year on a sunny windowsill or in a warm conservatory. 

• How do I prevent spring onions from bolting? Keep the soil consistently moist and avoid extreme temperature fluctuations. Harvesting regularly also helps prevent bolting. 

• What is the best way to store harvested spring onions? Store spring onions in the fridge, wrapped in a damp paper towel or placed in a glass of water. They will stay fresh for up to a week. 

By following these steps, you can enjoy a bountiful supply of crunchy spring onions, perfect for adding a fresh, mild onion flavour to your favourite dishes. Whether grown in a garden, allotment, or on a windowsill, these versatile vegetables are a must-have for UK gardeners. 

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