Mustard greens are a leafy vegetable with a distinct peppery, and sometimes spicy, flavor. A member of the Brassica family along with cabbage, kale, and broccoli, mustard greens are celebrated in cuisines around the world and are packed with vitamins and minerals. Mustard greens are cool-weather plants that bloom and die when the weather is hot. The greens’ flavor gets stronger with heat as well. And like most greens, the texture gets tougher. Mustard greens can tolerate frosts but not hard freezes. Mustard greens require at least eight hours of direct sun each day, but like most greens, they can tolerate as little as five to six hours of direct sun. Just remember that any amount of shade reduces production.