I've not grown this but advice is to prune in early spring so I would say March time.

Thank you very much for your comment. Yes, that is the time when usual pruning of bushes and trees are done, however, I read that this bush should be pruned in summer. That was one of the reasons of my question - probably those who grow it should know...

Hope so Katarina though my understanding is you dead after flowering and prune in spring

I can't find much information re pruning - its often used as a "nothing will grow here cos its got poor light" filler for difficult spots, or as rough hedging, so most instructions are how to get it to thicken up and ensuring suckers aren't left to run. I've never grown it purposely, but its been present in many gardens I've handled over the years, and its a pain in the proverbial. Damn thing spreads like crazy, under the fence to next door, along the fence, and so on. It does tend to have a rather lax, open habit as a shrub, so I think the only time you might see it as a dense one is if its treated as hedging. The only time I've seen anything like a reasonable display of berries has been on unpruned ones, let to go a bit wild, sorry Katrina.

Hello Bamboo, Thank you very much for all your information! I am happy to hear from you again, as I didn´t see you here for quite a long time.
Maybe I can use special underground border around it, from plastic in order to prevent disobedient spreading...hm...will see, it has flowers and berries for the whole autumn and winter, so I will try to cut it at the end of spring what will happen.
Wishing you all the best in a New Year.

I'm still a member, Katarina, but don't contribute much any more. Thanks for your good wishes, and the same to you!