How far did you cut them back? I really hope you just trimmed them. Either way its highly ill advised to cut them back this time of year...ecspecially when you just planted them.

I have ames as well. They were late to leaf out fro me this year. Looking good right now. Flowers don't pop for another 2-3 weeks yet. I'm in zone 5.

Lastly there aren't many best issues. If you do have any you should spray the plant right before bud break...or there are soild treatments that last up to 3 months.

I've had my 'Ames' Kalm St John's Wort for years and it is starting to be a little too woody in the interior with less foliage. Can I give this shrub a renewal pruning? If so, how far back can I cut it and at what time of year is best for doing this. I do not mind skipping flowers for a year or two.

trim the height all over and cut 1/3 of the branches to the ground, ideally the oldest ones. It blooms on new wood which means you prune in the early spring before the blooms come out.