Japanese Komatsuna Mustard Seeds. 30 to 50 Days to full maturity. 8 to 12 days to microgreens harvest. Brassica rapa var. perviridis. Annual. Heirloom, Non-GMO, Open Pollinated. Komatsuna is popular traditional, dento yasai, Japanese green leafy vegetable. It has tender, deep green leaves, and a mild, flavor that resembles spinach. A quick growing, upright type, it can be harvested all seasons with succession planting due to heat and cold tolerance. Delicious eaten at any stage. About 10,000 Seeds / Oz.