Organic California Giants Zinnia Seeds. 50 days to maturity. Can be grown in containers. Ornamental. Zinnia elegans. Heirloom, Non-GMO, Annual. Dating back to 1926, Zinnia California Giant is a mix with several shades of color. These flowers are enormous and can become 4 to 5 inch double flowers. Approx. 3,900 Seeds/oz.