Hummingbird and Butterfly Gardening: Zone 5 Butterfly Garden Needs Advice From any and all!, 0 by Meredith79

Meredith79 wrote:
I'm sure Tab already gave you great info but I can share my thoughts on milkweeds. The two easiest Milkweeds to grow from seed are A. curassivica http://davesgarden.com/guides/pf/go/604/ (this would be annual for you) and A. tuberosa http://davesgarden.com/guides/pf/go/73/ . I also have found swamp milkweed http://davesgarden.com/guides/pf/go/539/ easy, but I just tossed the seed out in an empty bed, I didn't try growing it indoors. I ended up getting at least a dozen plants sowing it directly in the garden. I probably threw about 300 seeds out there though. I am pretty sure those need a cold stratification period to grow from seed, unlike the first two which germinate at room temps.. I wintersowed some A. purpurascens http://davesgarden.com/guides/pf/go/81058/ last year and ended up with 3 seedlings in the garden. Not very good odds on those, cosidering I put hal the pack in the ws container. So you may not want to try those. Be very wary of the common milkweed http://davesgarden.com/guides/pf/go/40130/, they send out runners underground and are impossible to get rid of without tearing up every inch of dirt. They didn't die after I sprayed them with an organic herbicide either. I don't mind them growing in most parts of my yard but it seems they prefer to grow right along my front entry path, which is the only area I try to keep neat and traditional. Their darn runners go under the concrete slab (so you can't get them all) and even grow out the area that is cracked from settling, so you can see why I wouldn't want them there! ;) Although the Monarchs here seem to be most attracted to them.
There are lots of online resources for milkweed if you absolutely can't try seeds. Just look at the vendor links from the plantfile pages and you should find reputable places that way.

Picture is of scarlet milkweed I grew from seed last year. (These are practically impossible to kill, my leftover seedlings were left to die in the flats and still struggled on!)