Lactuca sativa The classic head lettuce. Medium-sized heads have tightly packed, crisp, sweet leaves. Just like in the supermarket, only fresher. Harvest in about 62 days. 1g. Light Full sun Row spacing 18 inches Plant spacing 12 inches Planting depth Barely cover Days to germination 7-10 Plant height 10-15 inches Gardener\’s Notes:Cool-season crop. Start seed indoors 4 weeks before last frost or sow outdoors in early spring as soon as soil can be worked. Time planting so lettuce grown when day temperatures are 60-70F and nights are 45-50F. Sow 2-3 seeds per inch. Lettuce needs light to germinate, cover very lightly. Thin seedlings. Keep soil moist. Harvest entire head. In mild climates plant fall through early spring.