http://www.ourhabitatgarden.org/creatur ... owing.html
"Growing milkweed for monarchs
One of the keys to having monarchs—for their survival now and in the future—is having lots of milkweed. Because of suburbanization and Roundup-Ready crops, there's a lot less milkweed than there was in the past. This is a disaster for monarchs since monarch caterpillars can eat nothing but milkweed. No milkweed, no monarchs!
We want lots of monarchs, so we need to plant lots of milkweed for them to lay their eggs on. We've tried to maximize our milkweeds in a number of ways—especially since it's sometimes difficult to find them for sale or at least to find them for sale at an affordable price."
Great website on who to germinate seeds and divide plants, etc.