The Mammoth Grey Stripe Sunflower: This heirloom sunflower is from the late 1800's, and it's a big one! Reaching 8 to 12 feet tall, the flower heads measure 10 to 15 inches across. Sunflowers should be sown directly outdoors, since their long roots need space to develop and dislike being disturbed. Mammoth Grey Stripe Sunflower is a fantastic addition to your Home Flower Garden! Win a contest for the biggest Sunflower in town! Summer Height: 8-12 feet Spacing: 18-24 inches Light: Full Sun Soil Moisture: Medium This heirloom sunflower is from the late 1800's, and it's a big one! Reaching 8 to 12 feet tall, the flower heads measure 10 to 15 inches across. Sunflowers should be sown directly outdoors, since their long roots need space to develop and dislike being disturbed. Common Names: Mammoth Grey Stripe Latin Name: Helianthus annuus Species Origin: US Native Wildflower Hardiness Zones: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12: Germination Ease: No Stratification The Mammoth Grey Stripe Sunflower: This heirloom sunflower is from the late 1800's, and it's a big one! Reaching 8 to 12 feet tall, the flower heads measure 10 to 15 inches across. Sunflowers should be sown directly outdoors, since their long roots need space to develop and dislike being disturbed. In late spring after the soil has warmed to 70-75 degrees F, plant several seeds together 1” deep and 6” apart in rich, well drained soil; the seeds will begin to germinate in 8-10 days. The protection of netting or a screen may be necessary to prevent birds or animals from eating the seeds as they begin to sprout and develop; keep the soil moist. Thin to the strongest seedlings. Sandy soil is not recommended for sunflowers, since this provides little support and nutrients. All our seeds are Home Grown in the USA - Isla's Garden