The shrubs mentioned in this calendar for pruning do NOT HAVE TO BE PRUNED in many instances. These are simply optimum times if you so wish. For instance, some of the evergreens are best pruned back by mid summer in order that they gain sufficient 'hardy;' growth before the onset of the following winter.. You will soon be aware of why 'when to prune shrubs' is as important as 'how to prune shrubs'.
Pruning is necessary for some shrubs - not because they actually
need it, but more because we have either planted them in the wrong
place, or they are simply not conforming to what we think they should
look like. But if you are going to prune, it is essential that you know when to prune shrubs, for if you prune some shrubs at the wrong time, you can lose flowers for a year or maybe two.
There are many other shrubs that simply need pruning to do their best for us - whether new lush foliage, stems or flowers. The downfall of pruning in many cases - certainly as our mailbox suggests - is that many shrubs are pruned at the wrong time.
This results in either cutting off the flower buds for the season - hence no flowers for a year; cutting off the stems in autumn which would normally give us a great display through the winter; or even pruning some types of shrubs/trees at the wrong time of year, which then allows fungal spores to enter!
Buddleja hard pruned in spring - ready to send a lot of new growth and large flowers.