SUNFLOWER, MAMMOTH GREY STRIPE 25+ SEEDS NEWLY HARVESTED, 8-12 Foot Tall July 8, 2026 Helianthus Annuus. Mammoth Sunflower 8-12 feet tall with 1 foot wide flowers! GREY STRIPE. Annual that likes full sun-part shade 8-12′ tall. A Striking Colorful Sunflowers in warm shades of orange and yellow.