This 30+ yr old smoke bush is in Toronto and has suffered winter kill this past winter over most of it. Although about 1/6 th of it has slowley come back and there is some new growth on some of the larger branches I would like to prune it back to maintain a consistent shape. This would mean pruning below the new growth into the thickest branches. I am considering cutting into the main branches below where the smaller ones branch out to help keep the shape. It seems I have missed the most opportune window for pruning. Is the pruning strategy okay and should I wait until early next spring to do this?
Thank you for your advice.
Healthy smoke bushes (Cotinus coggygria) respond best to pruning in late winter/early spring, prior to leafing out. Dead branches, however, need to be removed regardless of the time of year. There are several Toronto Master Gardener entries describing pruning techniques for Cotinus. You could start with the following link below, and also search “cotinus” on the Toronto Master Gardeners website. This link also refers you to an instructional video which may be of use. https://www.torontomastergardeners.ca/askagardener/dead-limbs-on-smoke-bush/
You will note that there are 2 approaches to pruning. You can either prune back about a third of the branches to the trunk and shape the remaining branches, or, you can cut the shrub right back to within 5 to 7 cm of the ground (known as coppicing) to renew the entire plant. More information on coppicing is available from this (British) website: https://www.rhs.org.uk/advice/profile?PID=121
Because there is such severe die-back in the case of your smoke bush, I would suggest the more radical approach. My one concern that it is too far into the season to perform this treatment because the shrub has already sprouted. Cutting off all of the live branches on your shrub could kill it. My recommendation is to cut out the dead wood right away and leave the viable branches for this growing season. Early next spring, you can go ahead with the full coppicing prior to sprouting, in order to rejuvenate (and re-shape) your smoke bush.