Outsidepride Orange Tithonia Mexican Sunflower Plant Seed - 500 Seeds Grow Goldfinger Mexican sunflower seeds in USDA zones 4 - 11 as an annual flowering plant grown from tithonia seeds. Tithonias will grow to 40 inches tall in no time and produce beautiful orange 3 inch flowering blooms for your flower garden. If you are looking to attract beneficial insects as well as butterflies and humming birds then you want to plant these flower seeds which are heirloom. Plant 2 to 3 Goldfinger Mexican sunflower seeds per plant to begin growing tithonia plants. Mexican sunflowers reach their mature height quickly, bloom profusely through the summer months and will die with the first hard frost.