Giant Sunflower
The Mongolian Giant Sunflower is a true behemoth, towering 12 to 14 feet tall with flower heads stretching 12 to 18 inches across, crowned by seeds that are more than twice the size of ordinary sunflower seeds. This heirloom annual thrives in hardiness zones 2 through 11, reaching full maturity in 90 to 100 days under full sun. The massive seeds are highly nutritious and prized for snacking or feeding wildlife, making this variety as practical as it is visually stunning.
Full Sun
Low To Moderate
2-11
168in H x ?in W
Perennial
High
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Standing up to 14 feet tall with plate-sized flower heads, the Mongolian Giant produces seeds that are approximately 1 inch long, more than double the size of typical sunflower seeds. These enormous seeds are packed with nutrition and offer genuine satisfaction whether you're harvesting them for your own table or feeding hungry birds. The sheer scale of this variety transforms any garden into a focal point, creating dramatic vertical interest that few other plants can match.
The oversized seeds of the Mongolian Giant are harvested for snacking, offering a substantial and nutritious treat straight from the flower head. Home gardeners also grow this variety to provide premium seed for feeding birds and wildlife, taking advantage of the huge seed size and nutritional density that birds find irresistible.
Start seeds indoors 2 to 4 weeks before your average last frost date using biodegradable pots, which can be planted directly into the ground to avoid disturbing the sensitive root system that sunflowers develop.
Transplant outdoors 1 to 2 weeks after your average last frost date, or when soil has warmed sufficiently. Plant biodegradable pots directly into the ground to minimize root disturbance.
Direct sow in the garden as soon as soil warms to at least 55 degrees Fahrenheit, typically 1 to 2 weeks after your average last frost date. Seeds will sprout in 7 to 14 days under favorable conditions.
For cut flowers, harvest in the morning just after the flowers open, using a clean knife. For seed harvest, wait until the bracts begin to shrivel, then cut the heads and hang them upside down in a barn or shed to dry. Once fully dry, rub the seeds off the heads; for eating, soak overnight in 1 gallon of water with salt before drying completely.
Cutting the mature central flower head will promote the development of side-shoot flowers, extending your bloom season and increasing overall flower production throughout the growing period.
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