Although all 6 of my butterfly weeds survived in my (wet) research plot, they didn't grow well. I only had 5 eggs and one larva. However, the plant in my front yard has been there for 5 years, and it has been very hardy. In addition, it supports a large number of monarch larvae. More than once this summer I counted a dozen larvae at one time. As you can see from the photo below, mine is a large spreading plant, mostly because rabbits chowed down on it. (Which caused new shoots to grow up to replace them). As you can see, the plant extends from the rock to the yardstick.
Usually eggs are laid on the underside of plants, but this one was laid on top of a butterfly weed.
In just 2 weeks, the caterpillar below has grown from a larva the size of a dash to 2 inches long. It has molted 5 times, and is now ready to find a place to hang and form a chrysalis.