Lettuce (Lactuca sativa) is a fast, easy crop: heads are ready six to eight weeks after sowing, and loose-leaf types even sooner. It grows best in the cool weather of spring and autumn. Sow indoors from March and plant out from April, 25–30 cm apart, with the base of the plant level with the soil – planted too deep, it rots. Seed can also be sown directly from April, but it often fails to germinate above about 25 °C, so in summer sow in the evening and in shade. In heat and drought lettuce bolts and turns bitter, so choose bolt-resistant varieties for summer and give them light shade. Keep the soil evenly moist and water in the morning. Slugs are the main pest; check beds after rain and use traps or barriers. Sow small amounts every three to four weeks for a steady supply, and use lettuce as a catch crop between slow-growing tomatoes or brassicas. A last sowing in August gives heads in October.