MAMMOTH BLACK RUSSIAN SUNFLOWER is a HUGE plant and Flower. They can get 10 feet tall. They have huge leaves, and a thick, sturdy stalk that will produce a giant 12-16" feathery yellow flower with hundreds of seeds. The seeds are ready when the flower nods and drops its petals. Easy to grow from seed. Pretty much a carefree, drought tolerant plant once the seedlings are established. Water once or twice a week if no rain. Over-watering can cause disease. A little slow-release organic fertilizer will increase seed production. 25+ Organic seeds from Kansas per order. Thank You! helianthus annuus. Annual. Spring, soil temp 70F+. SOW 2 seeds per plant,1" Deep, about 3ft apart. Keep moist. Germination 7-10 Days. Thin to single best seedling. Use scissors to cut out unwanted seedlings. Height 10 -15 ft x 3 ft wide. Medium water. Compost or organic slow-release fertilizer will increase seed production. Flowers are yellow. Blooms mid to late summer. Seeds are ready when flower nods. Buy Seeds Online Organic Seeds Heirloom Seeds Non-GMO Seeds Vegetable Seeds Flower Seeds Herb Seeds Fruit Seeds Garden Seeds Seed Starter Kits Rare Seeds Bulk Seeds Indoor Gardening Seeds Seed Catalog Seed Packs for Sale Sustainable Seeds Greenhouse Seeds Seed Suppliers Planting Seeds Home Garden Seeds