When can I prune my shrub?

https://www.ipm.iastate.edu/ipm/hortnews/2000/2-11-2000/prunetime.html

 

PRUNING GUIDE:

EVERGREENS – DURING MONTH OF JUNE AFTER NEW GROWTH HAS APPEARED; NO MORE THAN 1/3 OF PLANT AT A TIME; BE SURE TO GIVE THEM A GOOD THOROUGH SOAKING RIGHT BEFORE THE GROUND FREEZES FOR WINTER

FLOWERING SHRUBS (SPIREA, BARBERRY, WEIGELA, BURNING BUSH, ETC.) – DURING DORMANCY; TYPICALLY DECEMBER 1^ST THRU MARCH 15^TH. NO MORE THAN ½ OF PLANT AT A TIME; ALSO CAN SHAPE/DEADHEAD AFTER BLOOM HAS FINISHED TO CLEAN THE PLANT UP & PROMOTE NEW GROWTH

NOTES:

SPRING BLOOMING SHRUBS (LILAC, FORSYTHIA, ETC.) – PRUNE AFTER BLOOM IN SPRING HAS FINISHED; TYPICALLY JUNE 1^ST-JULY 1^ST, THESE PLANTS SET BUD IN FALL FOR SPRING BLOOM, SO PRUNING IN FALL OR WINTER WILL COMPLETELY REMOVE YOUR SPRING BLOOM.

HYDRANGEAS – TYPICALLY LEAVE ALONE EXCEPT FOR DEAD BRANCHES, DROOPING BRANCHES; CLIP DEAD BLOOMS OFF DECEMBER THROUGH MARCH.

LARGE LANDSCAPE SHRUBS (WEIGELA, CRANBERRY BUSH, ETC.) – BE SURE TO PRUNE 1/3 OF OLDEST STEMS OUT EVERY SEASON ONCE ESTABLISHED FOR 5 TO 7 YEARS, THIS WILL ENCOURAGE NEW GROWTH FROM THE BASE, KEEPING THE PLANT FULL AND LEAVED OUT FROM TOP TO BOTTOM.

FLOWERING SHRUBS – ‘WILD HAIRS’ CAN BE CLIPPED BACK ANY TIME DURING GROWING SEASON TO KEEP SHAPE, BARBERRIES ARE A TYPICAL CANDIDATE.