how to fertilize lettuce plants
Growing Head Lettuce. 1  1. Choose a head lettuce variety for indoor planting. 2  2. Prepare seed trays. 3  3. Sow the seeds 4-6 weeks before the last spring frost.  4. Give the seeds plenty of sunlight and 1  water. 5. Transplant into the garden.  6. Fertilize the lettuce three weeks after 1  transplanting. 7. Cut mature leaves.