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.
3. Trim back the entire plant when it reaches 3 to 6 inches high, or approximately every 10 days. Cut back to within 1 to 2 inches of the ground. Most loose-leaf lettuce varieties grow back from a severe trim to produce more leaves.
For maximum lettuce production, it's wise to select a site where the soil drains well, yet retains some moisture. The soil should also be rich in nitrogen and potassium, The best way to accomplish this is to work in plenty of organic matter (compost, rotted manure, or leaf mold) that will loosen and enrich the soil.