LOP TILL YOU DROP

A vigorous winter cutback will give you masses of fresh bushy growth, says Monty Don – as long as you know what to prune

Now – or during the next six weeks – is the ideal moment to do all the winter pruning to the trees, shrubs and climbers in your garden. But before you start wielding your loppers in an enthusiastic cutting frenzy it is worth being really clear why you are pruning and what will most benefit the plant and the way that it performs for you.

If you are pruning flowering shrubs, timing is critical. Those that flower in the first half of the year, such as spring-flowering clematis, lilac, chaenomeles or daphne, do so on wood that has grown in the previous growing season – i.e. April to August of last year. The time to cut these plants back is immediately after flowering – certainly before the longest day of the year on 21 June – to give the new growth time to mature and form flowering buds for spring. Prune these in winter and you will have new growth – but no flowers.

The opposite holds true for plants that flower after June.

They form their buds on new growth, so you can afford to be ruthless in winter and cut them back hard in the knowledge that this will instigate healthy new shoots which will carry all the flowering buds later in the summer.

The critical thing to remember about all winter pruning is that the harder you cut, the more vigorous will be the regrowth. So for plants that produce their flowers on older wood you will have fresh shoots that will not bear flowers for a year or two. If you prune an apple tree too hard each winter it will make new growth but no flowers – and therefore no fruit. Prune this new, sappy growth the following winter and it will happen all over again.

But you can use this method to coppice trees or shrubs. This means cutting them right down to the ground every few years to stimulate vigorous new shoots that either have good-coloured bark like dogwood (cornus) or willow (salix); useful straight rods for bean sticks and supports, like hazel; or that grow extra-large decorative leaves as a result of the pruning, like paulownia or catalpa.

It will also reinvigorate an old ‘leggy’ hedge. Trimming it in summer will maintain its existing shape whereas a hard winter cutback will result in fresh bushy growth to fill gaps.

If you wish to restrict growth, either to train into shape or if the plant has outgrown available space, leave the heavy pruning to July when the foliage is fully grown and before the roots start to store food for winter.

So prune all trained fruit such as espaliers, cordons and fans in winter to encourage new growth and then again in July to reduce established growth. In this way you can grow and manage complex shapes.

Finally, however ‘correct’ your pruning, it must look good. Take your time, stand back to examine your handiwork and enjoy it!

PRUNING TIPS

Always use really sharp tools for the job. It’s easier, safer and a sharp edge cuts cleanly leaving less risk of damage to the plant or infection. Good secateurs, loppers and a sharp pruning saw will deal with almost everything.

Do not paint or cover any large wounds after pruning, as this just seals in moisture and disease. It’s better to leave a clean cut and let the wound heal itself.

Mulch all climbers and shrubs after pruning to set them up for their burst of extra growth in spring.