55 Days to maturity. Brassica juncea var rugosa. Kekkyu Takana Mustard Seeds. Non-GMO, heirloom, cool-season annual. This cool-season heading mustard is a great early spring variety. It has a tightly wrapped head, sometimes called a “wrapped heart.” It’s somewhat frost resistant and should be planted about a month before the last frost of the season. Keep it cool as it bolts when the temperature gets to 75°F or more. This mustard can be harvested a bit early for a delicious flavor, helping to avoid the warmer days. Approx 10,000 seeds / oz.