Sun; Average to dry well drained soil; Big stout stems and leaves like common milkweed but non-aggressive. This is one of the best showy garden milkweeds. Dark purple flowers appear in June-July on the top of a 2-3' tall plant. Flowers are lightly fragrant and attract lots of monarch butterflies. Zone 3-8; WV, PA, NY ecotypes. // Seed packet, about 30 seeds. Germination requirements: 60 days cold, moist stratification.