Kohlrabi Kossak, Brassica oleracea (gongylodes group) (Green) 20 Organic Hybrid Seeds by David's Garden Seeds Days to Maturity: 45 Non-GMO, easy to grow and hand packed here in the United States by David's Garden Seeds. Giant kohlrabi for storage and fall/mild winter production Reaches a diameter of up to 8 incehs, and the interior will still be sweet, delicious, and tender Germination rate: 70%