Mustard Greens is also called Mustard and Mustard Spinach, and is a Southern green. It has a stronger taste than Spinach and Swiss Chard. You can harvest Mustard Greens in the fall and spring in the South, as it is a cool weather crop. Mustard Greens is a hardy plant, but it does not do well in very hot weather. You can have successive plantings throughout the year. Mustard Greens seeds are usually planted directly in the garden. For spring planting, plant seeds 30 days before the last frost, and 70 days before the first autumn frost for a fall crop. Plants can grow 18 - 24" tall.