Lettuce - Lakeland This is a crisp and crunchy 'iceberg', ideal for the British climate. It has large, tight, heavy dark green heads and few outer leaves. Sow outdoors thinly, from March to July where they are to crop, 1.5cm deep, directly into finely-prepared, fertile, moisture-retentive soil, which has already been watered. Allow 30cm between rows. Early sowings may benefit from cloche protection. Seedlings usually appear in 7-14 days. Thin out to 25cm apart. Water well until plants are established. Regular sowings, made every two to three weeks, will ensure a continuous supply. Harvest from June to October.