Monday, October 20, 2008


Lettuce, lactuca sativa, of the family Compositae, is the most popular of all salad crops. It is a cool-season vegetable, growing best at temperatures between 15o and 18o C (59o and 64o F). It will often bolt, or produce seed prematurely, if it is grown in mid summer heat. Of the four principle lettuce types, the most popular, the crisp-heading lettuces (Iceberg is a well-known variety), have brittle, prominently veined leaves, butterhead types (Boston, for example) have softer leaves and a smooth texture, loose-leaf varieties (such as oak-leaf) do not form heads but grow as clusters or bunches of leaves, and cos lettuce, or ramaine, forms a long, loaf-shaped head. Cos is slower to bolt than other lettuces and is therefore useful as a warm weather crop. No cultivated lettuce variety has been found growing in the wild, although there are many wild lettuces, and it is assumed that domesticated varieties may be cultivars of the weed L. serriola (prickly lettuce).

Lettuce is usually propagated by seeding directly in the soil. Leaf lettuce is harvested about 40 days after seeding; head lettuce, from 70 to 90 days.

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