- You will get 101+ Seeds of Prairie Sunflower Flower Seeds. - Seller Notes: ?Helianthus petiolaris. ? U.S. Grown seed. Tested 1/23-Germination 94%. Packed 1/23.?. - Planting Time: 10 Weeks. - Soil Type: Clay, Loam, Peat, Sand. - Life Cycle: Annual. - USDA Hardiness Zone (F): 9 (20 to 30 F). - Soil pH: Neutral. - Watering: Medium. - Sunlight: Full Sun. - Prairie Sunflower aka Lesser Sunflower can grow in clumps that make it look like a small bush, but it is not unusual to see single plants scattered around. It is not uncommon along sandy or gravelly roadsides in mid to late summer. While some references put the plant height at up to 6 feet, I have never seen it more than about 4 feet tall in Kansas. Prairie Sunflower is distinguished from other KS native sunflowers by its alternate, mostly toothless, often triangular leaves and flowers with a brown, larger than average center disk. The plant most closely resembles the common sunflower (Helianthus annuus) but in miniature. petiolaris range covers much of North America. Very easy to grow. 100+ Seeds per order. Thank You!. - Some American Native Wildflower seeds need to go through a cold winter to germinate. This plant is one of them. They do this so the seed won?t sprout in fall, only to have the seedling not make it through a cold winter. I have stratified these seeds to simulate a cold winter(stratification) This raises the germination rate considerably. Thanks for looking!!. - Helianthus petiolaris ? prairie sunflower - Annual. - Full sun. - Spring, soil temp 70F+. - Sow 2 seeds per plant, press into soil 1"deep, about 24" apart. Keep moist. - Germination 7-14 days. - Medium water. Light organic fertilizer if needed. - Flowers are Yellow. Blooms mid-summer through fall.