Hi,
I have one of these in my garden. For various reasons, I didn't prune in the autumn as I normally do, so I'm setting about it now. I know from past years that the plant grows substantially in the summer. Is it OK at this time of year to prune really hard? I'm always reluctant to do so in case I kill it, but how much could I cut back if I start now. And should I cut one in three to ground level? Thanks.