Winner Kohlrabi Seeds. F1 Hybrid. Non-GMO, Annual. 45 to 55 days to full maturity. Brassica oleracea var. gongylodes. This medium-early maturing white kohlrabi hybrid is a winner. Large plants grow upright to a medium height. The uniform, semi-globe shaped thickened stem grows to 4" or more with a green skin. Leaves are dark green. Pick when tender as stems become fibrous with age. Kohlrabi prefers mild or cool temperatures. Approx. 10,000 seeds / oz.