Lettuce is the most popular and commonly consumed vegetable in the United States with a consumption exceeding 25lbs per person every year. Lettuce originated from the Mediterranean and Near East (Persia) area in Greek historical records from 450 BC.
There are many varieties of lettuce including iceberg, romaine, leaf, and butterhead.
Lettuce is grown in the spring and the summer when the temperature is moderately hot. The optimal temperature for growth is 60 to 65° F, but lettuce can germinate at 35° F. The plant flowers and produces seeds at 70-80° F and if the nights are cool, lettuce can withstand 80-85° F. The capability of withstanding heat depends on the type of lettuce where types such as romaine, butterhead, and leaf types can withstand higher temperatures. The crop can be produced in 40-50 days, but most head varieties require 60-80 days to mature.
Nutrition
The nutrient contents of lettuce vary with the type, where darker greens tend to be more nutrient dense.
- Shredded romaine lettuce (1/2 cup): 4 kcal, 26.6 g water, 0.5 g protein, 0.7 g carbohydrates, 0.1 g fat, 0 mg cholesterol, 2 mg sodium, 0.5 g fiber, 219 RE vitamin A.
- Shredded iceberg lettuce (1/2 cup): 3 kcal, 26.5 g water, 0.2 g protein, 0.6 g carbohydrates, 0 g fat, 0.3 g fiber, 2 mg sodium, and 4 RE vitamin A.