Experts and BHG readers answer.
Transplanting Knockout Roses
Thanks for writing. You can prune your Knock Out roses anytime except early to mid-autumn without harming the plant. However, the more you cut it back during the growing season, the longer you'll have to wait for a fresh crop of flowers.
If you just transplanted the roses, they're probably experiencing a bit of shock --- keep them well watered and see what happens --- they should start to recover in a couple of weeks.
---Justin, Senior Garden Editor, BHG.com "