Spring onion 'White Lisbon' (Allium cepa ) has a pleasant mild flavour, so it's no surprise that it's the most popular variety grown for use in salads. It's also excellent for stir fries and oriental dishes. Height and spread in a season, 30cm x 23cm (12in x 9in)RHS Award of Garden Merit Grows best in well-drained soil in full sun. Can be sown thinly in pots and window boxes. Direct sow outdoors in spring on well drained soil in full sun. Sow thinly, 1cm (Â½in) deep, with 30cm (12in) between rows. Prepare the planting area several weeks in advance by incorporating some well rotted garden compost to improve drainage and soil fertility. Avoid planting onions on freshly manured soil. When large enough to handle, thin seedlings to 23cm (9in) apart. Alternatively sow seed indoors in module trays at a depth of 1cm (Â½in), using free-draining, seed compost. Place in a propagator or seal container inside a plastic bag at a temperature of 10-15C (50-59F). Seeds should germinate in 10-14 days. Once germinated, grow onions on in cool conditions until all risk of frost has passed and they are large enough to plant outdoors at a distance of 23cm (9in) apart. Water the plants thoroughly after planting. Cover with a protective netting or fleece to prevent attack from birds and insects.