Kale Microgreens Seeds. Brassica oleracea. Non-GMO. Kale micros are dark green sometimes with a bluish hue or a redish highlight. The greens are easy to grow and fast. Grows well in both soil and hydroponic pads. Germination is fast, with seedlings first appearing in 1 to 2 days. Harvest between 8 and 12 days. Flavor of mild cabbage or kale, but slightly sweeter.