- You Will Get 250 Seeds Of Maximilian (Prairie) Sunflower Helianthus Maximiliani Flower Seeds. - Description: - Name: Maximilian's Sunflower. - Other Common Names: Prairie Sunflower. - Scientific Name: Helianthus Maximiliani. - Color: Yellow. - Plant Seeds: Outdoors After Frost / Indoors Weeks Before Last Frost. - Plant Height: 36 - 96". - Plant Spacing: 18 - 24". - Bloom Time: All Summer. - Hardiness Zone: 4 - 10 (& Reseeds Itself Easily). - Light Requirements: Sun - Part Shade. - Soil & Water Preferences: Average.