Lettuce (Lactuca sativa) is one of the most popular and widely consumed vegetables, today and historically. The Mesopotamians, Greeks, Persians, Romans, Egyptians, and Chinese considered lettuce a leafy delicacy and grew seeds for oil.
Columbus brought lettuce and seeds on his voyage to the New World, as did most European explorers in their colonization efforts. In the United States, per capita consumption is more than 25 pounds annually.
Derived from wild, stemmy varieties, lettuce was cultivated over the centuries into firmer heads with more leaves. Cultivation and breeding over the years has perfected leaf shape, flavor, and resistance to disease and bolting. Newer hybrids are bred to resist brown blight and mildew.
Iceberg lettuce, also called roundhead or crisphead, got its name in the early 1900s as it was shipped in ice-filled containers. Romaine is so named because of its popularity in early Rome. Mesclun is not a variety itself, but a mix of baby lettuce and leafy greens such as radicchio, arugula, and others.
Types & Varieties
Lettuce comes in four main varieties: leaf lettuce, including red and green varieties, where the thinner leaves and loose heads can range in taste from delicate to slightly bitter; butter lettuce including both Bibb and Boston, which is a sweeter variety when grown in cooler weather; romaine or cos, popular in Caesar salads, has dark leaves and firm, crunchy leaf ribs; and crisphead or iceberg, which has tightly packed leaves with a higher water content.
Top producers Arizona and California account for most U.S. production with New Jersey as a contributor as well. In Arizona, butter lettuce or butterhead tends to be easier to grow than iceberg.
In California, butterhead, leaf, and romaine lead the charge. Within the butterhead type, a popular variety is Margarita. Common leaf varieties include both green and red; greenleaf varieties consist of Big Star, Burgam’s Green, North Star, and Tropicana, while redhead varieties include Red Fox and Red Tide. Romaine varieties include Darkland, Green Towers, Progeny, and Sun Belt.
New Jersey’s Bibb and Boston varieties include Esmeralda, Ermosa, and Optima. Common leaf types include Black Seeded Simpson, Grand Rapids, Salad Bowl, and Two Star (all green), and red leaf varieties consist of New Redfire, Red Express, and Red Sails. Under the romaine umbrella, popular varieties include Green Forest, Green Towers, Ideal Cos, and Pyramid Cos.
Overall, lettuce is hardy, growing well in cooler temperatures and resisting frost and cold. Leaf varieties grow quickly, maturing within 50 days; some butter varieties take up to 75 days to mature and can tolerate different soil and weather conditions.
Romaine, because of its vertical growth, does well in tighter rows and can tolerate a variety of weather conditions. Iceberg, which takes up to 80 days to mature, is the least tolerant. To cultivate firm heads, cooler conditions are needed (45°F at night is ideal).