Mammoth Grey Striped Sunflower is a towering heirloom annual that grows up to 10 feet tall, producing massive flower heads averaging 12 inches across filled with delicious, edible seeds. This stately garden giant thrives in zones 2 through 11 and reaches full maturity in 90 to 100 days, making it a reliable choice for gardeners seeking both visual drama and a productive seed harvest. Its grey-striped seeds are prized for their flavor, and the plant attracts bees and other pollinators throughout the growing season.
Full Sun
Moderate
2-11
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These sunflowers command attention from seed to harvest. The plants stretch skyward to 10 feet, crowned with enormous flower heads that function as both stunning focal points and prolific seed producers. Growing them takes roughly three months from direct sow to mature heads ready for harvesting, and they thrive across nearly the entire continent thanks to their wide hardiness range. The real draw for many gardeners is the sheer abundance of edible seeds packed into each flower head, combined with the plant's role as a magnet for beneficial pollinators.
Mammoth Grey Striped sunflowers are grown primarily for their edible seeds, which are harvested and consumed fresh, roasted, or used in baking and cooking. The flower heads also serve as a spectacular garden focal point and draw pollinators, making them valuable for supporting bees and other beneficial insects. Many gardeners grow this variety specifically for seed saving, continuing the heirloom tradition of collecting mature seeds for next year's planting.
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Direct sow seeds outdoors after the last frost date when soil temperatures reach at least 50 degrees Fahrenheit. Plant seeds 1/2 inch deep, spacing them 18 to 24 inches apart. Seeds typically sprout in 7 to 14 days when soil is warm and moist.
Allow flower heads to mature fully on the plant for 90 to 100 days from direct sowing. Heads are ready to harvest when the back of the flower turns brown and begins to dry, and the seeds pull away easily from the head when rubbed gently. Cut or break mature heads from the plant, then hang them upside down in a warm, dry location to fully cure. Once completely dry, rub the seed head vigorously to release the edible seeds.
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“Mammoth Grey Striped represents a continuous thread in American seed-saving tradition. As a heirloom variety, it has been grown, selected, and preserved by gardeners across generations who valued both its architectural presence in the garden and the productivity of its seed harvest. The variety's persistence in seed catalogs and home gardens speaks to its reliability and the genuine appreciation gardeners have for sunflowers that deliver on both aesthetic and practical fronts. Heirloom sunflowers like this one carry forward the knowledge of farmers and gardeners who understood that a plant worth growing needed to earn its space through beauty and bounty alike.”