Without doubt, the factor that affects shrubs more than any other is the actual timing of pruning operation. There is certainly a best time when you should prune shrubs and trees - in particular if flowering excellence is high on your list. Prune at the right time, and you will get flowers when due; pruning at the wrong time often means no flowers!
Our pruning calendar set out below - month by month - gives the low down on when is the best time to prune shrubs and trees in the garden.
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.
One of the problems of writing a Calendar of Shrub Pruning, is the fact that every year brings seasons which are either earlier or later than usual - particularly spring and autumn, and of course, being a world wide website, there will be different hardiness zones in different countries, together with different general climatic conditions which will also affect the optimal timing of any pruning for some types of shrubs. This can affect the time when you prune your shrubs. You will have to gain knowledge about your own particular time zone to know this.
The basis of our calendar, is that of minimum average temperature of approximately -7deg. This corresponds to most areas within the UK. It is roughly equivalent to Group 8B on the USDA Hardiness Zones Table. As with all things in life, times change. So do temperatures - regardless of your feeling about global warming.
The calendar below will be added to.
Pruning at this time of year is normally confined to shrubs that flower on growths that were produced in the previous year. Therefore by pruning now, you are giving the plant time to produce new growth this year, which will also bear the flower buds for next year. Leave it too late, and there will be no time for the shrub to produce next year's flower buds. For this group of shrubs - prune immediately after flowering.
However, there are also several evergreens that can be pruned at this time - if they are simply being grown for foliage effect.
September can be a useful month for pruning certain shrubs - and trees - in certain ways! It is the month that gardeners normally start to do a bit of tidying-up, and snipping away at everything that looks overgrown can be a bit tempting. Wait! Don't!
The single most important this about pruning now, is to ensure that you are not cutting off the flower bud stem for next spring.
October - November
Winter Pruning Wisteria should take place in October or November
November - December
December - January
Cornus alba, stolonifera and sanguinea