Mustard - Mibuna Mibuna Mustard Seeds. 41 Days. Brassica rapa var. japonica. Open Pollinated, Non-GMO. Similar mizuna greens, the mibuna mustard is a flavorful Japanese green strap leaf mustard with mild mustard flavor. Although very similar to mizuna plant, mibuna is differentiated by its smooth, pointed leaves rather than the sharp and serrated leaves of mizuna. Although not as tenacious as mizuna, the mibuna produces a slightly stronger and more complex culinary mustard profile. Mibuna greens are a hardy cool weather crop best sown direct 4-6 weeks before final frost date, or can be started indoors for transplanting. Sow 5-6 seeds 1/2 inch deep and 4 inches apart in fertile, well-drained soil in full sun-part shade. Seeds germinate in 3-7 days, thinning to 1 plant every 12 inch once true leaves establish. Like lettuce, harvest large outer leaves while allowing smaller leaves to mature. Approx 8500 Seeds per ounce. Why Mountain Valley Seed Company? Find out why over half a million customers have chosen Mountain Valley Seed Company for their seed and gardening needs. 100% of our seeds are Non-GMO, and we have a huge selection of organic seed options to choose from. In addition, we offer an amazing selection of Microgreens Kits, Wheatgrass Kits, Indoor Herb Garden Kits & more. Growing together since 1974, Mountain Valley Seed Co. has been providing high-quality seeds at incredible prices to local and nation-wide growers alike.