I had planted some lettuce seeds in a pot last fall, and had occasional lettuce leaves all winter, and then lots of leaves this spring. And I kept pulling the leaves off rather than taking the whole plant….until a hot spell when it started to bolt (which means the center core starts acting like a plant and growing very, very tall). The lettuce also gets tough and bitter, so I just let it grow to see if it would flower. And it did! Very small but beautiful flowers.