Hi everyone. I have a Buddleja Davidii Royal red which is about three years old and in a container. I have never really pruned it before apart from taking off any dead stems. It flowers ok in the summer but is not prolific. I have read that I should be pruning it now and ''cutting back hard to 2" of last year's growth.'' Is that correct and will pruning it increase flowering? It always seems odd to me to cut back something that is leafing up nicely. Thanks.