Mammoth Grey Stripe Sunflower Seeds – Giant Yellow Annual

Mammoth Grey Stripe Sunflower Seeds

Make a bold statement in your garden with Mammoth Grey Stripe Sunflower, a giant annual sunflower variety known for towering stems and spectacular golden-yellow flower heads.

Botanically Helianthus annuus, this Non-GMO, open-pollinated variety may grow approximately 9-12 feet tall under favorable conditions, producing impressive flower heads up to about 12 inches across.

Mammoth Grey Stripe is an excellent choice for flower gardens, tall borders, living screens, wildlife-friendly plantings, and striking summer garden backdrops.

Product Highlights

• Non-GMO, open-pollinated sunflower variety
• Bright golden-yellow flowers with large central disks
• Flower heads up to approximately 12 inches wide
• Plants may reach approximately 9-12 feet tall
• Attracts bees, butterflies, and seed-eating birds
• Easy-to-grow, full-sun annual

Plant Profile

• Common Name: Mammoth Grey Stripe Sunflower
• Botanical Name: Helianthus annuus
• Family: Asteraceae
• Variety: Mammoth Grey Stripe
• Seed Traits: Non-GMO, Open-Pollinated
• Plant Type: Ornamental Flower
• Life Cycle: Annual
• Growth Habit: Tall, Upright
• Flower Color: Golden Yellow
• Flower Head Size: Up to Approximately 12 Inches
• Plant Height: Approximately 9-12 Feet under favorable conditions
• Plant Width: Approximately 36-40 Inches
• Days to Maturity: Approximately 90-110 Days
• Germination: Approximately 4-10 Days
• Sowing Depth: Approximately 1/2 Inch
• Light: Full Sun
• Soil: Fertile, Well-Drained Loam
• Water Needs: Moderate

Growing Mammoth Grey Stripe Sunflowers

Direct sow seeds outdoors after the danger of spring frost has passed.

Choose a sunny planting location with good drainage and protection from strong winds.

Sow seeds approximately 1/2 inch deep. Plant 2-3 seeds per planting spot if desired, then thin to the strongest seedling after emergence.

Maintain a final spacing of at least 18 inches between plants. Additional space can help accommodate mature foliage and larger heads.

Under favorable growing conditions, seeds commonly germinate in approximately 4-10 days.

Full Sun and Soil

Grow in full sun, ideally with at least 6-8 hours of direct sunlight every day.

Mammoth Grey Stripe performs best in fertile, well-drained soil but can adapt to a range of garden conditions.

Because mature plants can become extremely tall, consider growing them along the northern side of garden beds to reduce shading of smaller plants.

Watering and Support

Maintain consistent moisture during germination and early growth.

Established sunflowers tolerate some dry conditions, but adequate watering supports vigorous growth and flower development.

Tall sunflowers may require staking when grown in exposed or windy locations.

Bring Pollinators and Birds to Your Garden

The large golden-yellow flower heads attract bees, butterflies, and other visiting pollinators.

As the flower heads mature, birds may feed on the developing seeds.

Leave dry seed heads standing for wildlife or collect the mature seeds for appropriate uses.

Harvesting Sunflower Seeds

Monitor the flower heads as the petals begin to fade and the back of each head changes from green to yellow-brown.

If you want to save the seeds, place breathable mesh over developing heads to discourage birds from removing them.

Once the heads are mature, cut them with a length of stem attached and hang them in a dry, ventilated location.

Remove seeds after the heads have dried thoroughly.

Garden Uses

• Tall garden backdrops
• Living sunflower screens
• Flower borders
• Pollinator gardens
• Bird-friendly plantings
• Summer flower displays
• Educational gardening projects

Frequently Asked Questions

How tall do Mammoth Grey Stripe sunflowers grow?

The variety is commonly described as reaching approximately 9-12 feet under favorable growing conditions. Actual height depends on soil, light, weather, and spacing.

How large are the flowers?

Flower heads can reach approximately 12 inches across under suitable conditions.

Are these sunflowers annual or perennial?

Mammoth Grey Stripe is an annual sunflower that completes its life cycle in one growing season.

Should I start the seeds indoors?

Direct sowing outdoors after the last frost is recommended. Sunflowers generally establish well from seeds planted directly in the garden.

Do Mammoth Grey Stripe sunflowers attract birds?

Yes. Mature sunflower seed heads can provide food for visiting seed-eating birds.

Can I harvest sunflower seeds?

Yes. Allow the seed heads to mature and dry before collecting seeds. Seeds intended for food use require appropriate handling and processing. The retail seeds sold in this packet are intended for planting.