They're just babies, not enough heft to the stem to stand up to weather yet. They should be fine next year. If they're smooshed into the soil, staking won't hurt, but probably not necessary because they'll be going dormant soon in your zone.

Karen

Thanks for the info. One or two of the larger ones (maybe 8" tall) even had small blooms on them.

They'll be fine. The roots haven't had enough time to adjust to the new spot to hold the stems up. They'll develop more underground this fall and in the spring, and they'll be ready to hold up the new stems next year.

Martha