 Generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. It can be plagued with numerous nutrient deficiencies, as well as insect and mammal pests and fungal and bacterial diseases. L. sativa crosses easily within the species and with some other species within the Lactuca genus; although this trait can be a problem to home gardeners who attempt to save seeds, biologists have used it to broaden the gene pool of cultivated lettuce varieties. World production of lettuce and chicory for calendar year 2010 stood at 23,620,000 metric tons (23,250,000 long tons; 26,040,000 short tons), over half of which came from China.
