When should Rose of Sharron be pruned?

Answer 1

RoS can be pruned starting in mid-Fall through early-Spring, but please read to the end for a kicker.  Pruning in Fall will provide the maximum affect on growth, shaping, and flowering.  Although you may read and be told that these hardy shrubs can be cut back during the Winter months, I personally have never achieved my desired results by cutting back any type of flowering shrub during Winter.  As they say, "Your mileage may vary."

In the Fall, the flowering should be well over with and some quite cold - if not frosty - nights should be past before you start pruning.  In the NorthEast, this will generally start in mid to late October.  Pruning in Fall will do the most to achieve fewer, larger, more vibrant flowers.  These wonderful flowers attract everything from Bumble Bees to Humming Birds.

As you might expect, the timing is the exact opposite in Spring.  Once the very cold or frosty nights are on the wane and some crisp Spring weather is underway you can start pruning.  Once the RoS has started to significantly leaf out, you'll be stuck waiting until Halloween again.  Pruning in Spring will produce good results, so don't hold back just because you were too busy carving pumpkins and sewing costumes in October, (and then it snowed!).

And here's the kicker I promised in the beginning.  The RoS is a RIDICULOUSLY hardy shrub.  I put it in the same class as Forsythia.  You can prune it literally any time of the year if you need to.  Pruning from late-Spring through the Summer will very substantially impact flowering and growth for the season, but it will come roaring back next Spring.  If you're going to do this, don't skimp; make it worth it.