- You Will Get 75 Seeds Of Red Swamp Milkweed Asclepias Incarnata Flower Seeds. - Description: - Name: Swamp Milkweed. - Other Common Names: Rose Milkweed / Red Milkweed / Swamp Silkweed / White Indian Hemp / Butterfly Weed / Butterfly Milkweed. - Scientific Name: Asclepias Incarnata. - Color: Dark Pink – Mauve. - Plant Seeds: Fall / Cold Stratify 1 Month. - Plant Height: 36 - 60". - Plant Spacing: 18 - 24". - Bloom Time: Summer. - Hardiness Zone: 3 – 8. - Light Requirements: Sun - Part Shade. - Soil & Water Preferences: Average – Wet.