This is as you’d expect a fairly large subject. For the winter pruning of Wisteria, Clematis, fruit, roses and grape vines, please refer to relevant articles in ‘Sages & Gurus’.
General Tips
The critical questions before you start on the pruning are : –
- Why?
- When?
- How?
Regarding trees, larger shrubs and hedges add in: –
- Is there a Tree Preservation Order?
- Do I live in a Conservation Area or National Park?
- Is a tree surgeon needed ?
And finally: –
- Does the tree, shrub or hedge bear edible fruit?
- Is it a wildlife habitat?
- Is a formal or informal look required? (generally more relevant for hedges).
It is also inadvisable to prune when there is a heavy frost, or late in the day when a frost is forecast. This is because the pruning cut is an open wound and the frost may damage the tree or shrub until it has healed over.
Pruning Tools
Possibly a be self evident comment – but use appropriate tools for the job and be sure that they are sharp.
It is generally advisable to work in pairs when working at height, with particular power tools or where areas need to be cordoned off. Follow the relevant protocols set out for your garden or organisation. Failure to do so will invalidate any potential insurance claims.
Hand tools
- Bypass secateurs – (scissor shaped) for cutting living stems and branches
- Anvil secateurs for dead wood, or where a slight crushing of the stem is less important
- Loppers – basically secateurs with a longer handle; often have a ratchet motion which gives greater cutting power. They may have elbow length handles or be extendible to reach into lower tree branches.
- Pruning saw -has curved handle and or blade which makes reaching into the shrub or tree much easier than with a straight saw.
- Pruning knives – as saw but smaller
Power tools
These require further training above that which should be given to personnel using hand tools. They may be petrol, battery, mains electric and include hedge trimmers, pole pruners and chainsaws.
These are covered in detail in other articles, but briefly, in winter: –
Evergreen Trees and Shrubs, Conifers
Evergreens can theoretically be pruned at any time of year. Generally, however, they are best pruned in late summer.
Sometimes they need to be pruned during the winter, perhaps to make room for a new building, fence or planting scheme. Or because they have been damaged.
Start by removing, dead, diseased, damaged and dying stems and branches. Then those which are rubbing against each other.
If the aim of the pruning is to make space, you should still consider what needs to be done to produce a balanced, attractive tree or shrub. Ideally not more than 15 – 20% of the top growth should be removed in one go. This figure excludes dead and diseased branches.
Note re conifers – the majority of these will not regrow where they are pruned back to old wood.
Deciduous Trees and Shrubs
Firstly, is this being grown for its –
- ornamental flowers
- decorative winter stems
- decorative winter bark
- none of the above, particularly
It may be helpful to colour code shrubs for when they should be pruned, particularly if there are less knowledgeable staff or volunteers. And actually as a useful aide memoire!
Late flowering shrubs, those that produce flowers on the tips of the current season’s growth are pruned in the late winter or early spring after they have flowered. They may be pruned by a third or even a half earlier in the winter in order to prevent damage from storms if the shrub or small tree is likely to rock and loosen its roots.
Apart from this, follow advice as above for evergreens.
Coppicing and Pollarding
Those trees and shrubs grown or their winter bark or stems may be coppiced or pollarded to increase their decorative effect rather than simply pruned. However this technique is also used to allow more light to the lower levels of a planted border. Both techniques cause new shoots to develop rapidly during growing season.
Coppicing is a pruning technique that cuts trees and shrubs to ground level, to a low stump or potentially knee high. The actual height pruned to may depend on the desired decorative effect and surrounding plants during both the summer and following winter. It creates a multi-stemmed plant.
Pollarding is carried out on standard trees, which are cut close to their head at the top of a clear stem. Ideally, this method should carried out on young trees and shrubs once they have reached the preferred height. Older trees can be pollarded, but care should be taken not to prune off too much at one go.
Climbers / Climbing Shrubs
There are variables; for example, is it self-clinging or does it twine around a trellis? This will affect the way in which pruning is done.
- The general rule of thumb is to follow the advice above for flowering shrubs.
- If the climber is grown for foliage, then deciduous plants are usually pruned in the dormant period.
- Where the climber bears berries overwinter, it is best to prune in the late winter or early spring.
- Purely decorative vines are often treated as per Wisteria for pruning purposes. Vines being grown for grapes, follow particular pruning regimes.
Hedges
When hedges are pruned should take into account the potential for nesting birds. It is an offence under the Wildlife & Countryside Act 1981 to damage or destroy the nest of any wild bird while it is in use or being built. The bird nesting season is usually considered to run from March to August. This means that a late winter prune may run foul of the law, so plan timings carefully.
- Formative pruning refers to getting the shape correct and is carried out on young plants.
- Deciduous hedges have formative pruning carried out in winter, including after bare root planting.
- Old hedges which are out of control would require restorative pruning, preferably during the dormant season.
- Whether your hedge is formal or informal will also guide how it is pruned.
Marie Shallcross
Plews Garden Design and Consultancy