There has been so much confusion among butterfly lovers about whether or not they should plant Tropical Milkweed since a scientific study and press release (http://news.uga.edu/…/monarch-butterflies-loss-of-migratio…/) came out on January 15th.
Thanks to the authors of that study for helping to clarify some of the details with their response on the Monarch Joint Venture website.
Note that Tropical Milkweed is not a villain, and neither are the people who plant it, but it is suggested that Tropical Milkweed be used as a carefully managed garden plant. In southern locations throughout the United States, Tropical Milkweed should be cut back to the ground in the fall if it is not grown in a place where frost will kill it. Doing this will help to minimize the possible spread of parasites that can infect Monarchs.
It is important to remember that Tropical Milkweed is sold widely across the US at many major garden outlets as a decorative container plant. In all likelihood, it is not a plant that will stop being used by gardeners any time soon.
The entire study about Monarchs and Tropical Milkweed can be found online.