There is little care required for the growth of this lettuce. Once the head reaches a desired size, and before it bolts (begin to elongate) the whole head can be harvested and stored in the fridge for up to 2 weeks. 

For ongoing harvest, you can begin harvesting once the leaves reach about 4 inches tall. Harvest the outer leaves of the head and let the inner leaves continue to grow and mature. Just snip either single outer leaves or grab a bunch of them and cut them with scissors one inch above the base of the plant. Be careful; if you cut into or below the base, the plant may die, so leave the small leaves in the middle to regrow easily.

Do not cut more than a third of the plant if you want it to keep growing.