As it is possible to harvest it several times through the season, leaf lettuce gives a constant supply of clean greens. Leaf lettuce grows 14 and prefers cooler temperatures. In summer places that are moderate, the slow-bolting red kinds, including Red Sails and Red Fireplace, might create all summer. Harvesting red lettuce correctly encourages development and does not harm the plant.
Harvest the first set of leaves about 4-5 days after planting, when the leaves are about 6″ or greater in total. Cut the leaves in the plant using a clear knife near their foundation.
Cut outer that is clean leaves twice or once weekly, depending how quickly the plant grows and replaces the foliage. Leave the the inner foliage set up to carry on creating and developing.
Once the plant reaches full-size, remove the leading third of the whole plant together with the knife or shears. Harvesting in this way encourages a brand new flush of development.
Before it bolts, generally before summer temperatures go above above 80 degrees Fahrenheit, but this depends on the range, harvest the whole plant. Cut off the plant at ground-level using the knife that is clear.