The peppery, purple-colored Purple Frills brightens up any salad with both flavor and appearance. Its shiny, finely serrated leaves with a light green base have a mild mustard taste that intensifies as they grow larger. Purple Frills is fast-growing and can be cultivated in early spring, but it provides the best harvest in late summer, fall, and winter. It is highly cold-tolerant, and the leaves even take on a deeper purple hue as the temperature drops. In early summer, it quickly flowers and produces yellow, edible blossoms. This type of mustard green has been used both fresh and quickly cooked in northern India and the Himalayas for at least 5,000 years. Annual.