Sunflower – Mammoth Grey Stripe

HELIANTHUS – Mammoth Grey Stripe

• Growing Temp 70°F – 85°F

• Days to Maturity 90-100 days

Ease of Cultivation and uses: The ‘Mammoth Grey Stripe’ sunflower is a classic giant variety recognized for its impressive height and large, striking flower heads. It is relatively easy to grow, making it a favorite among both novice and seasoned gardeners. This sunflower thrives in full sun and well-drained soil, often reaching heights of 8 to 12 feet. The seeds can be harvested and enjoyed as a nutritious snack, while the stunning blooms make for excellent cut flowers and add a bold statement to any garden landscape.

Direct Sowing: For direct sowing, plant ‘Mammoth Grey Stripe’ sunflower seeds outdoors in the spring after the last frost date when soil temperatures are at least 70°F. Sow the seeds 1–2 inches deep and space them 18–24 inches apart in rows that are 3–4 feet apart to allow for their large size and robust growth. Water the seeds well after sowing and maintain consistent moisture until germination, which generally occurs within 7–10 days. As the plants grow, they may require some support to prevent bending, especially in windy conditions.

Early Sowing for Seedlings: For an early start, sow seeds indoors 4–6 weeks before the last expected frost. Use biodegradable pots filled with seed-starting mix, placing one seed per pot and covering it lightly with soil. Maintain a temperature of about 70°F to encourage germination. Once the seedlings develop their first true leaves and the risk of frost has passed, transplant them into the garden, spacing them 18–24 inches apart. Water well after transplanting to help them adjust to their new environment.

Harvesting: To determine when ‘Mammoth Grey Stripe’ sunflowers are ready for harvest, observe the flower heads as they begin to droop and the backs turn yellow. This indicates that the seeds have matured. Cut the flower heads in the morning when they are dry, leaving several inches of stem for handling. If you plan to collect seeds, allow the heads to dry completely, or cover them with a paper bag to protect them from birds and pests until you are ready to harvest.