Some of the lower leaves on my swamp milkweed are turning orange/yellow and dying. Here's a link to swamp milkweed problems if anyone is interested:
http://www.mymonarchguide.com/2007/08/m ... blems.html
http://www.ourhabitatgarden.org/creatur ... blems.html
I know the sun can cause the tips of the leaves to darken. I just added some organic fertilizer to see if it helps.