Red Kale Seeds. Brassica napus. Annual. Open Pollinated, Heirloom, Non-GMO. Excellent option for growing as a microgreen. 8 to 12 days for microgreen harvest, 20 to 25 days for baby leaf, 50 to 60 days to full maturity. The leaves of Red Kale are purple color, flat with cut margins. Mature plants are 18- 30" tall. Baby leaves and microgreens are tender, durable and have nice flavor. Most vegetables leaves or sprouts having red or purple color is called “anthocyan” which is generally developed by lower temperature. Approx. 8,000 seeds / oz.