Head type lettuces generally produce a moderate to tight head, and are usually grown out to full size to harvest. Plant in succession every 2-3 weeks to extend your season. Head lettuces need a longer season and are usually less tolerant of heat than leaf types or romaines. Lettuce is best direct sown as soon as soil can be worked in cool weather and cool soil temperatures (45-65F). Plant 1/8 inch deep in rows 12-18 inches apart in loose soil, and keep moist. Thin to 8-12 inches apart, using those pulled for baby greens. Lettuce grows best in cool weather (75F or cooler) and can be of poor quality, bolt, or go dormant in warm weather.