august probably isnt the best time to be pruning ..

best pruning advice would be when the tree is leafless ... and by that i mean when you can see the structure of the plant.. to make better pruning cuts ... you dont just go lopping off the tall part and hope for the best ... in a perfect world ...

where are you.. big city name.. and we can tell you when it should be done.. and you can give us better pix ...

ken

Frank Laudone,

Here's a smokebush that is allowed to do its thing, maybe that's why it has so many flowers. I like the way it has been allowed to grow out into the road, so what. It shows that humans don't have to have a chokehold on everything.

BTW where you live has nothing to do with the response to your question.

Smokebushes are frequently coppiced - cut back hard to a set woody framework on an annual basis. Some take them down very low (6-12") and others leave a larger permanent structure of anywhere from 18" to 3-4' or more. They will regrow to almost their full size each season but you will omit any flowering or the "smoke" :-))

This should be done in spring just as the buds begin to develop. But long, lanky shoots like on the right side of the OP's plant can be cut back in summer as desired.

I am in zone 6b RI just wanted to cut back the long loopy stems on the right side of the picture. But I would leave it if I was going to lose the ability to leaf out or the Smokey

the issue is.. wherever you cut it.. it will respond with 3 to 5 new stems ...

you dont want that at height.. as the lower part wont be able to hold it up later .. as the stems get bigger ...

so.. you would want to cut it much further back... so that it grows appropriately into the future ...

when its leafless.. we can look at the structure.. and give you a better idea where to cut it .. for the best result ...

also... you dont want to do this.. as we near fall .. because you dont want fresh new growth to trigger ... when we want it slowing down for fall.. and dormancy ... if new growth doesnt properly harden off ... they can get winter damaged ...

all that said ... you cant kill this thing by pruning it.. and if that piece is just pissin you off.. go cut it off ...

we can always come back next year.. and cut it again... lower down ...

ken

"the issue is.. wherever you cut it.. it will respond with 3 to 5 new stems ..."

I have not found that to be the case with Cotinus....with some shrubs, yes, but not this one.

Cutting back hard or coppicing each year will eliminate the potential for flowering. But it enhances the foliage effect, usually resulting in larger, more intensely colored leaves. But there is really nothing to stop you from heading back the long, lanky stems earlier in the season after they elongate fully. You will just miss some flowering on those but the rest of the shrub should flower as expected.

Cut away. Least amount of responsive growth at this time of year.

Yup. Just trim those long shoots back now to balance it out. You can do more drastic cuts in the spring if needed.