To space plants properly, you'll probably have to thin the plants. Thin leaf lettuce plants to 4 to 6 inches or more between plants, depending on plant size. Thin butterhead and romaine plants to 6 to 10 inches apart. An organic mulch helps conserve moisture, suppress weeds and keep soil temperatures cool. If weeds become a problem, either pull them by hand or cultivate very shallowly.
Deep cultivation can damage the roots.
To reduce midsummer bolting, plan your garden so the lettuce will be in the shade of taller plants, such as tomatoes or sweet corn, during the hottest months. Insect pests and diseases can occasionally cause problems on lettuce. To learn what's damaging your plants and how to stop the damage, call the county extension office. Harvest tender Harvest any lettuce types when they're full-size but young and tender. Overmature lettuce is bitter and woody.