To define a number range, you have to create a new number interval: 1  Specify an alphanumeric key with up to 2 characters. 2  Specify the limits of the number interval.  Mark the number range if it is planned for external number assignment.
Inspect the lettuce plants for leaves that are ready to harvest. Most leaves are mature enough once they reach 1 to 3 inches long, but they should still be tender up to 6 inches long. Cut off the outer leaves of the plants with a small pair of garden shears to harvest just a few leaves.
After about 3 to 4 weeks you can cut and harvest. Here is a nice closeup of another lettuce stump beginning to regrow with just a small amount of water indoors. Here we put 3 romaine lettuce stumps in 1/2 inch of water in a glass container and put on our kitchen window sill. (image credit here).