Lettuce is a cool-season crop that grows well in the spring and in the fall in most regions. Lettuce seedlings will even tolerate a light frost. Temperatures between 45 F and 65 F are ideal.
Garden lettuce is far superior, in both taste and vitamin A content, to supermarket brands.
Because lettuce grows quickly, the best approach is to plant a small amount at a time, staggering your plantings.