Organic Common Milkweed Seeds. Asclepias syriaca. 70 days to maturity. Perennial in zones 3 to 8. Can be grown elsewhere as an annual. Non-GMO, heirloom, open-pollinated, certified organic by OTCO. Called milkweed because of the milky substance that flows when you break the stem, this common milkweed is an heirloom native to North America with a huge range from Canada to Georgia. Approx 4000 seeds / Oz.