- You Will Get 100 Seeds Of Butterfly Weed Mexican (Asclepias Curassavica) Flower Seeds. - This is for 100 Mexican Butterfly weed seeds this is a perennial it grows best in zone 8-11 this likes full sun. - This blooms a red to orange color and likes full sun. - This is often called tropical milkweed this can take up to a month to germinate. - We have been told these are also used in medicinal herb. - These are best brought indoors when it gets cold these are very nice looking in 3 gallon pots. - The get to be about 36" tall and bloom summer to fall.