Sow outdoors April to May. Leeks can be sown directly outdoors, although plants may take a bit longer to get going and therefore be ready to harvest slightly later. Choose a sunny location for best results. Sow directly into a seed bed 1.5cm deep, in shallow trenches 20cm apart. Cover the seeds with fine soil and water well. Keep the soil moist and remove any weeds as they appear. When large enough to handle thin the seedlings out to 5cm apart. When stems have grown to the thickness of a pencil, transplant them to their final growing position. Make 10cm deep holes in the soil with a dibber, spaced 15cm apart, in rows 30cm apart. Place seedlings in the hole and just water them in. This will bring soil down around the roots without compacting it and restricting the future growth of the stems. Keep the soil moist and remove any weeds as they appear.