8 to 12 days. Lime Streaks Mizuna Microgreens Seeds. A beautiful Asian mustard green that can be harvested as a microgreen from 8 to 12 days, or a baby green at about 25 days. At the micro stage, the cotyledons are green, and the stems are yellow-green. Lime Streaks Mizuna Mustard Microgreens slight tang along with the classic mustard greens spice.