I've got to try this. Regrowing lettuce from the remaining hunk: Save the end from your lettuce and put into a little water (about a half inch). Change out the water every day. The lettuce will grow back incredibly quick, too. The one on the left was cut today. The middle one yesterday and the one on the right, the day before. You can see how much it grows in just two days!! But don't feel limited to romaine. This technique can also be used with green onions and celery.