Lettuce - Red Leaves Mixed This quick, decorative plants will grow in containers, producing lovely dark leaves, perfect for 'baby' leaves or full heads. Sow outdoors thinly from March to August where they are to crop, 1.5cm deep, directly into prepared, fertile, moisture-retentive soil, which has been watered. For cut and come again baby leaves, allow 15cm between rows, or sow thinly, directly into 25cm pots with drainage holes. Early sowings may benefit from cloche protection. Seedlings usually appear in 7-14 days. No further thinning should be necessary. Keep moist. Regular sowings, made every two to three weeks, will ensure a continuous supply of leaves. Pick a few from each plant when approx. 10cm high. They will regrow for up to 4 'cuts.' Harvest from April to October. For mature lettuces, allow 25cm between rows and thin to 20cm apart. Harvest whole plants from May.