Spring Pruning will rejuvenate the shrub to provide stronger stems and shoots which in turn will produce better foliage throughout the summer months to come.
Eucalyptus gunni, Catalpa Aurea, Cotinus, Dogwoods, Sambucus, Robinia frisia, etc. will all benefit from a spring pruning.
Hard pruning in the Spring for Shrubs that flower late mid-late summer:
Tamarix pentandra (T. ramosissima)
Not Tamarix tentandra which requires different treatment, Hydrangea Paniculata types.
Also Buddlejas, Hardy Fuchsias, Hypericum, Lavatera, Prunus triloba (right after flowering), etc.
To rejuvenate old shrubs
or bring back into line shrubs such as Brachyglottis and Hypericum. Most shrubs can be given a new lease of life by cutting back hard. However, realise that the shrub will not stay small simply because you have given it a short back and sides. It will spring back into growth with a new enthusiasm.
Don't forget that it now has a root system that was used to supporting and feeding the old large shrub. It will 'pump' soil moisture and nutrients to ensure that the shrub gets back to 'normal size' as soon as possible.
Cutting shrubs back hard to near the ground is the normal procedure for producing masses of new shoots and lush colourful foliage. It looks savage - but it works. The pruned shrub will normally regain its normal - size prior to pruning - in the growing season Spring to Autumn.
If you have any doubts as to whether a particular shrub will respond by re growing, then simply cut out one third of the branches to be removed. Once they start shooting out near to or at ground level, then you can safely cut down the remainder of the shrub.
A huge framework of new branches is the result
This pruning job was done on a Sambucus racemosa Aurea, where abundant new shoots and foliage were required - and provided!
Eucalyptus Cotinus can be treated this way to (a) restrain the size of the shrub and (b) to produce spectacularly coloured foliage throughout the growing season. The same is true of Catalpa bignonioides Aurea.
The pruning should be carried out in early Spring (March) and a dressing of Fish Blood Bonemeal - or your own favourite balanced fertilizer - to help the plant produce the strong growth required.
Tamarix pentandra showing previous spring's pruning cuts. This Spring should see all of the shoots cut back to within 5cm (2in) of their starting point.