- You Will Get 100 Seeds Of Purple Smooth Violet Prairie Aster Aster Tanacetifolia Flower Seeds. - Description: - Name: Prairie Aster. - Other Common Names: Smooth Violet Prairie Aster. - Scientific Name: Aster Tanacetifolia. - Color: Lavender - Blue Violet. - Plant Seeds: Outdoors After Frost / Indoors Weeks Before Last Frost. - Plant Height: 12 - 18”. - Plant Spacing: 12 - 15”. - Bloom Time: Fall. - Hardiness Zone: N/A. - Light Requirements: Sun. - Soil & Water Preferences: Dry.