8-12 Days to maturity. Brassica oleracea. Organic Kale Microgreen Seeds. Kale microgreens are nutrient-packed and perfect for easy greens indoors and year-round. They are typically a rich, dark green but can take on a red or bluish hue as well. Try these as a perfect first-timer variety or as a staple for experienced microgreen growers alike. ~8,000 seeds/oz.