Onion White Lisbon (Allium cepa) Sow Indoors: N/A. Sow Outdoors: March- May / August- Sept. Row Width: 6" / 15cm. Harvest: March- July. Onion White Lisbon (Allium cepa): Quick growing spring onions, this variety is the most commonly used for salads. These onions have long white stems with stunning green tops. Very versatile, the spring onion is a must for any gardener. The most popular salad variety, producing quick growing tasty spring onions.Outdoor Planting: March- May sow seeds thinly 1.5cm deep direct in growing bed in rows 6" (15cm) apart. Keep the soil moist, and be careful not to over-water. No thinning is required. Plant in August- September to overwinter in a protected site. Ideal for successional sowing. Keep free from weeds.