Pruning an out-of-control smoke bush

(Question)

We have a smoke bush that the previous owners of our house planted approximately 8-10 years ago. I was able to keep up with its growth up until 2 years ago, but now it’s about 20 feet tall and nearly as wide. Because it is crowding our yard, I want to reduce its size significantly (to about 4-5′ high), by pollarding. Is it safe for the plant to begin this pruning technique, or is it too old? Should I wait until spring to chop it back, or can I do it now before the snow falls? All the info I can find now refers to plants only 2-3 years old.

Thank you kindly for reading!
Ottawa, ON

 

 

 

 

(Answer)

I went through this process this year. My Smokebush (Cotinus coggygria) was planted over 20 years ago, reached around 12’ and, in the last few years, had grown a bit ‘leggy’.

The best approach with an overgrown Smokebush is to prune it over few years. During this period your bush will not be blooming as flower buds are set in the previous year’s wood. In terms of season, the best time is in the early spring as the plant starts its awakening season. At this time you will be able to see, and manage, its shape better.

If your plant has still retained its shrub form, identify few strong stems that will make the base for your renewed shrub. If on the other hand, you only have one or two strong ‘trunks’, eliminate weak stems growing at the base.

Selectively prune 1/3 of the shrub. Space out the cuts so that, as the new stem start to grow, your shrub maintains a good and natural shape. Avoid any stems growing inwards or crossing. During the summer, you will see your shrub slowly filling up. Repeat the process the following year until the desired size and shape is achieved. Once that is the case, you can follow your normal upkeeping process as in the past. Your Smokebush will now be quite filled and will begin blooming subsequent years.

Lastly, you mentioned pollarding or coppicing your shrub. The only problem with these techniques is that with old plants, multiple growth will only occur at the end of the thick stem where the new shoots will grow quite ‘bushy’. These techniques are ok to use for rejuvenation if that is the look you want to achieve and, if you are familiar with them.

Good luck.