Pruning Basics

Many shrubs and plants live quite happily without the need
for pruning, clipping or trimming, as you look around your
garden you will see that there are plants that are right
for their situation - taking this to the extreme you could
 say that in it's natural environment no plant needs
pruning. Thats not the always the case with our garden shrubs,
and there can be additional benefits for our gardens from
either pruning, trimming or clipping - more or larger flowers,
fresh colored growth, more berries, more compact denser growth etc
  

Just a few things to start with

If you prune a shrub hard it will try to recover to it's original
height as fast as it can, so if you want long young canes
like with dogwood (Cornus) thats the way to go.

If however you tip it carefully you will end up with small weak
growth trying to replace what has been removed.

With that being said you are most likely to produce more
flowers and better foliage/stem color from younger growth

Before you rush outside and mow all your shrubs to the floor
there are other criteria to consider

Early flowering shrubs

Shrubs that flower in spring or early summer usually do so on
growth made last year. These are normally pruned just after
flowering (before mid summer) so that the new growth has
a whole season to ripen in readiness for next years flowering.
two common examples are Forsythia (golden bells) and
Philadelphus (mock orange) if you prune these too late you
will lose next years flower.

Late Flowering Shrubs

Shrubs that flower from the middle of summer onwards, these
flower on this years growth, so are pruned in the winter or
early spring they then grow and flower before the end of the year
two common examples are Buddleia (butterfly bush) and
Laveteria (mallow)

Old Shrubs

We need to be a bit careful here but in general most old shrubs
can be rejuvenated by a firm cutting back. (if there is no evidence
that the plant can grow from old wood you really need to make
sure of the of the plant first - if you have ever seen a conifer
hedge that has been cut too hard you will understand why).
If the decision has been made there are several ways to do it,
you can just go for it and reduce the volume in one hit - there
is a chance of "shock" which will hinder the plants recovery.

You can reduce the volume over two or three years taking
out 50% or 30% - this will reduce the chance of shock for the
plant and also could leave you enough plant for it to continue
to flower as the new growth replaces the old (sometimes
called replacement pruning).
 
Evergreens

Evergreens are best pruned in mid summer , this gives the new
shoots chance to grow after the spring frosts and to harden
before the winter frost.

Thanks for visiting