When you say butterfly weed, do you mean the milkweed with orange blooms? If so, I would separate them at least a few inches so the roots have a bit more space. These will grow into beautiful, long-lived plants that get bigger every year. They will spread to cover a twelve inch area in two years, and they drop seeds that produce occasional volunteers. Hope that helps.

Martha

Here's a pic of mine. There are about 10 plants all together, wintersown 2013/2014, transplanted in April 2014, and bloomed about a month ago.

Yes, it's milkweed with orange flowers, just like that one in the picture. I didn't think it would get that big in just one year! I'm looking forward to it!

I did the same thing as southergardening24. Mine bloomed the first year but were very floppy with lots of aphids. This year they are looking great and much bigger, so far no aphids. They still have a fair amount of lean to them, either due to rich soil or the wet spring we've had, but at least this year they're not laying on the ground getting muddy.

I put mine into a border with various prairie grasses, mostly prairie dropseed but also sideoats grama. I planted them in groups of three or so, spaced about 1-1.5 feet apart within each group. They have filled in and I am glad I did not space them any closer.