Leaf lettuce can be fairly easy to grow. Yet, if you want one of those nice specimens you can get at the grocery, you're going to have more of a challenge. "If you want a nice attractive head like they sell in the stores, it needs uniform watering and if you have temperature fluctuations, in lettuces, you can have this process called bolting," says Timothy Coolong, Ph.D., extension vegetable specialist for the University of Kentucky.
Bolting is a premature flowering or seed formation of the plant which can make it taste bad [source: Bradley & Courtier, The Editors of Garden Way Publishing]. "I would say that head lettuce (iceberg) has been hardest for me to grow because of the precise sun/shade needs that keep it from bolting," says Jonathan Mueller, landscape architect with Landmark.