How to Prune Correctly – Things You Need to Know

How to prune the trees and shrubs in your garden is a popular topic for Plews Gardening Lessons and Courses. In fact, it was the prickly problem of pruning roses that started me teaching ‘students’ how to garden in their own garden.

What I intend covering in this article are some of the basics for successful and safe pruning. There are links below to related blogs which you may find useful, including ones on topiary and hedges.
But what are the critical questions you need to ask yourself before you start on the pruning? They are: –

Why?
When?
How?

Regarding trees, larger shrubs and hedges you should also ask yourself: –

Is there a Tree Preservation Order?
Do I live in a Conservation Area or National Park?
Is the tree or hedge too large for me safely prune myself or do I need a tree surgeon?

Also: –

Does the tree, shrub or hedge bear edible fruit?
Are there birds nesting, is it a wildlife habitat?
Do you want a formal or informal look? This question is generally more relevant for hedges.

Knowing the answers to these questions will enable you to successfully prune the trees, shrubs and hedges in your garden. Or know that you need help to do so.

Oh, and one last, rather important tip – only woody perennials are pruned. Herbaceous perennials are cut back. This is because their growth remains soft and green; woody perennials develop a tough stem or trunk.

How to Prune Ornamental Flowering Shrubs

Some gardeners may find it helpful to colour code their shrubs to remind them when they should be pruned. You should also be aware that certain shrubs rarely need pruning, for example, Camellia, Cotoneaster.

Why?

Early flowering shrubs, say the January – June flowering period, flower on the growth they made after flowering the previous year. For example, Forsythia, Philadelphus.

Late-flowering shrubs which start from about July, produce flowers on the tips of growth they produce in that current year. For example, Caryopteris, Buddleia.

When?

Early flowering shrubs
The fundamental rule is to prune after flowering to allow next year’s flowering shoots to grow.

Late flowering shrubs
Tend to be cut back in the late winter and /or early spring after they have flowered.

How?

Early flowering shrubs
The shoots with old flowers cut back and, in most cases, something old from the base of each sawn out to encourage new shoots at ground level; up to a third of the shoots can be removed.

Late flowering shrubs
These are cut hard back to a low woody framework in March/April, from which they will rapidly regrow. A careful eye should be kept on the weather forecast, as a late or snap frost can cause die back.
They are sometimes pruned back by a third or half in the early winter. This is to prevent damage from storms if the shrub or small tree is likely to rock and loosen its roots.

Climbing Shrubs

There are variables with this type of shrub. For example, does your climber need to be supported, is it self-clinging or does it twine around a trellis? This will affect the way in which you prune it. When you prune it relates back to when it flowers and, possibly, when it fruits.

A general rule of thumb is to follow the advice above for flowering shrubs if your climber blooms. If it’s grown for foliage, then deciduous plants are usually pruned in the dormant period. Where the climber bears berries overwinter, you would probably prune in the late winter or early spring. Some of the comments about hedges are valid for climbers and wall shrubs.

Roses

There’s a link to pruning roses below.

Pruning Clematis

Pruning Clematis, like pruning Roses, seems to frighten many novice gardeners. It doesn’t need to, there are simple rules to follow. Return to the three questions of Why, When and How. The ‘when ‘ is answered if you know which flowering group your Clematis comes into.

Clematis fall into three main groups for the purposes of pruning. If you know which one you plants is, that’s half the battle. Check the label, or if you know which variety it is, you can look it up.

Why you’re pruning may be to increase number of flowers or to reduce a vigorous climber.

When to prune
Group 1: Prune mid to late spring, after flowering and once the risk of frost has passed
Group 2: Prune in February and after the first flush of flowers in early summer
Group 3: Prune in February

How to Prune Clematis

For the early flowering clematis, Group 1, little regular pruning is needed, although they may need thinning out when older. If this is required, plants can be cut back to 15cm from the base, after flowering. NB heavy pruning will reduce flowering capacity.

Group 2 clematis flower May to June on short shoots developed from the previous year’s growth. Some flower again in late summer on new growth. Generally they are only deadheaded. Taking down to a large bud immediately below the flower as soon as flowering is over will encourage a second flush.

Group 3 clematis are late-flowering clematis best pruned back hard in February each year to the lowest pair of buds. If left unpruned, the clematis will continue to grow from where it ended the previous season. This results in a tangled mass of growth, flowering above eye level with bare stems at the base.

Herbaceous clematis are treated as Group 3.

How to Prune Hedges

When you prune hedges 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.

Formative pruning refers to getting the shape correct. This is carried out on young plants and for the first two years after planting. Old hedges which are out of control would require restorative pruning. Maintenance pruning is usually carried out in summer.

Deciduous hedges have formative pruning carried out in winter, just after planting.
Evergreen hedges have formative pruning carried out in the spring after planting; and then for the two years following.

Whether your hedge is formal or informal will also guide how it is pruned.

How to Prune Fruit Trees

The point about fruit trees is that you are pruning to encourage a greater quantity of fruit. Three basic rules as to when you prune: –

Pip fruits – apples, pears and so on – are pruned when dormant ie bare branches.
Stone fruits – cherries, plums, etc – are pruned when they are in leaf.
Trained fruit tree forms – if pip fruits, they are summer pruned with occasional light winter pruning.

You also need to know whether the fruit is carried on mainly on the tips of branches or on spurs or clusters along the branch.
There are many variables, including fruit bushes and climbing fruits which need more detail, so this section requires a blog all of its own! (watch this space…)

Pruning Tools

Make sure you have the right tools and that they are sharp. An obvious statement which begs the question – “What are the right tools?”
Safety point, it is NOT a good idea to be reaching too far above you to make a cut into a tree branch. What will you do when it falls on your head?

Hand tools

Bypass secateurs (scissor shaped) for best cutting living stems and branches as they give a sharp, clean cut.
Anvil secateurs are best for dead wood, or where a slight crushing of the stem doesn’t matter.
Loppers are basically secateurs with a longer handle that you use two hands for and often have a ratchet motion which gives greater cutting power to your wrists. They may have elbow length handles or be extendible to reach into lower tree branches.
A Pruning saw has a slightly curved handle which makes reaching into the shrub or tree much easier than with a straight saw.
Pruning knives are used more by professional gardeners who like to have a good range of specialist tools. (Guilty as charged)

Power tools

If you use a chainsaw without wearing the proper safety clothing and without some form of training do not expect sympathy when you lose a leg.
That said, they can be useful in the right hands.

Finally

I began by saying pruning was the genesis of Plews Gardening Lessons. The point is that each garden, each tree and shrub in your garden, is going to vary from those in your neighbours’ and from the illustrations in a book or on line. I do offer ‘one-off’ pruning lessons as I’m aware it’s a pinch point for many.

Or you may decide an advice visit for what should be pruned and when will help resolve what the shrubs in your garden are and if they’re healthy and whether they need pruning. Because we can be flexible to resolve your gardening issues, the two can also be combined.

Please contact Plews for more help.

Happy pruning!

For further gardening advice and inspiration, check out Plews Potting Shed blogs, including the selection below and our monthly Tipsheet – You could come and find us on Instagram Pinterest and Facebook too.