For 8 years now I have been growing lettuce, cherry tomatoes, beans and cucumbers in 7 plastic storage boxes grouped together in the center of my little cottage garden. I let the the lettuce go to seed by accident a few years ago and was surprised to find it coming up by it self in March. This year I checked the boxes on St Patrick's Day and sure enough there was little sprouts. I have thinned and thinned the seedlings. I transplanted some but the transplants are not doing as well as the plants that I just thinned out. in a couple days I will thin again and this time the lettuce I thin out will be big enough to put in my salad. Here are a couple pictures. If you want to try this let me know and I would be happy to answer questions. It is so easy. These boxes provide all the lettuce I can eat from spring till late July when it becomes too bitter and goes to seed.