Mammoth
Asteraceae
Sunflower
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Mammoth Russian, introduced in the 1880s, was the variety that launched the American sunflower seed industry. It produces massive heads (up to 12" across) filled with large, striped seeds. Sunflowers are native to North America and were domesticated by indigenous peoples thousands of years ago.
Sunflowers are pure joy in the PNW garden. They thrive in our summers. Mammoth is the classic giant (8-12 ft with 12" heads). For smaller gardens, try branching varieties (Autumn Beauty, Velvet Queen) that produce multiple smaller flowers. Plant a row along a fence for a stunning August display. Sunflowers are also excellent companion plants — they attract pollinators and can serve as a trellis for pole beans (the Three Sisters method).
Direct sow after last frost when soil is 60°F+ (mid-to-late May). Push seeds 1" deep, 1-2 per sq ft. Sunflowers grow fast — they will be 6-12 ft tall by August. For giant varieties, thin to the strongest seedling. Stake tall varieties — PNW wind will topple them. Water deeply but infrequently. Harvest seeds when the back of the flower head turns yellow-brown and seeds are plump with hard shells — cut the head with 12" of stem and hang in a dry, airy place to finish curing. Cover ripening heads with paper bags to protect from birds.