Temperature and Humidity Romaine lettuce can be a bit more tolerant of heat than other lettuce varieties, though it is still a cool-weather plant, thriving in temperatures that range from 45°F to ...

A deadly E. coli outbreak linked to romaine lettuce quietly spread through 15 U.S. states in late 2023, causing one death and hospitalizing 36 people, including a 9-year-old boy who nearly died of ...