To grow enough lettuce for a small daily salad, you need a planter box that supports continuous harvest. The key is not one massive container, but a system for succession planting. For a steady supply, aim for a planter box that is at least 24 inches long, 12 inches wide, and 8-10 inches deep. This size allows you to plant multiple lettuce varieties, such as loose-leaf or romaine, with proper spacing of 6-8 inches between plants.
Start by sowing 6-8 lettuce seeds or transplants. Harvest outer leaves from each plant every few days, which encourages new growth. Once a plant begins to bolt (flower), replace it with a new seedling. With this rotation in a box of the recommended size, you can maintain 2-3 mature heads at any time, providing a handful of fresh leaves daily. Ensure your planter has drainage holes and use a quality potting mix. Place it in a spot with 4-6 hours of sunlight, water consistently, and you'll enjoy homegrown salads with minimal space.