Outsidepride Black Mustard Plant Seeds - 5000 Seeds Plant black mustard seeds directly in your herb garden in USDA zones 4 - 7 for an annual herb used for culinary spices in cooking. Brassica nigra, can grow up to 72 inches tall and produces a yellow flower. These heirloom, non gmo annual herb seeds are used for spice generally made from ground seeds of the plant with the seed coats removed. The seeds are flavorful although they have almost no aroma. The seeds are commonly used in Indian cuisine. Plant 5,000 seeds for every 600 square feet of herb garden you are planting outdoors.