I found them to be sturdier than I'd thought they would be. I had several plantings the last two years in different parts of my yard.
1) Hot blazing sun from late morning to mid-evening during a high temperature, drought-stricken summer (last year) produced a shorter plant, but it still had some blooms. This area was unprotected from extremes, but we don't really get all that much wind while these are growing.
2) Some protection from the southwest sun and wind by shrubbery and mid-size ornamental grasses produced the fullest plants with the most blooms.
3) On the deck in a shallow container with sun until evening and packed with too many other plants produced tall plants that weren't as visually appealing, but they still bloomed quite well. This is a self-seeded plant, growing this year.
It's a very easy plant to germinate and grow, and it self-seeds politely. A little protection from extremes just produces a bigger plant with more blooms.
to ATP!
I didn't intend to plant in this container because I thought it was too shallow to support plants well. I noticed those distinctive leaves in a few spots this spring and thought I'd get around to moving them out, but I never did. 
