Pruning basics: when and how to prune shrubs

Most pruning comes down to one question: when does the plant flower? If it flowers before midsummer, it usually blooms on stems that grew last year, so you prune straight after flowering. If it flowers from midsummer onwards, it usually blooms on stems produced this year, so you prune in late winter or early spring. Get that timing right, cut cleanly just above a bud, and you will avoid almost every pruning disaster.

You do not need to prune everything. Plenty of shrubs, such as skimmia and sweet box, are happiest left mostly alone. Pruning is a tool for a purpose: more flowers, better fruit, a healthier plant or a shape that fits your space. If you cannot name the reason for a cut, leave that stem where it is.

Why prune at all?

There are four good reasons to reach for the secateurs. First, health: dead, broken or diseased wood is an open door for rot, so it should come out whatever the season. Second, flowering and fruiting: many shrubs and fruit bushes flower more freely on young wood, so removing tired old stems encourages fresh growth. Third, size and shape: a shrub planted too close to a path or window will need regular restraint. Fourth, renewal: an old, leggy shrub can often be brought back to life with a staged hard prune over two or three years.

Every cut you make is also a signal to the plant. Cutting a stem back removes the dominant tip, so buds lower down wake up and grow. Hard pruning tends to produce vigorous, leafy regrowth; light pruning produces less. That is why cutting back an overgrown shrub hard in winter can make it come back bigger and bushier than before.

When to prune: a simple UK calendar

Late winter to early spring (February–March). This is the moment for shrubs that flower on the current year’s growth. Buddleja can be cut back to a low framework of stems around 30–60cm high; it will still reach head height and flower in July and August. Bush roses are pruned now too, before the buds fully break. In colder northern gardens, wait until March so the fresh shoots are less likely to be caught by frost. The March garden jobs page lists what else to prune that month.

Straight after flowering (April–July). Shrubs that flower in spring and early summer, such as forsythia, weigela and mock orange, form next year’s flower buds over the summer. Prune them as soon as the blooms fade by cutting a few of the oldest flowered stems right back to the base or to a strong young shoot lower down. Leave it until autumn and you will be cutting off next spring’s display.

Summer (July–August). Wisteria gets its first prune now: shorten the long whippy green shoots to about five or six leaves from the main framework. Trained apples and pears grown as cordons or espaliers are also summer-pruned to keep them compact. Lavender is trimmed after flowering, keeping just above the bare wood.

Winter (November–February, while dormant). Free-standing apple trees are pruned while leafless, when you can see their structure clearly. Wisteria gets its second prune in January or February, cutting the summer-shortened shoots back again to two or three buds. Summer-fruiting raspberries are cut after harvest in late summer, while autumn-fruiting types are cut to the ground in late winter.

Leave until spring. Mophead and lacecap hydrangeas keep their faded flower heads through winter as frost protection for the buds below. Remove them in March or April, cutting back to the first pair of fat, healthy buds.

How to make a good cut

Always cut just above a bud, leaving roughly 5mm of stem. Too far above and the stub dies back and rots; too close and you damage the bud. Where buds are alternate along the stem, make a slanting cut that slopes away from the bud so rain runs off. Where buds come in opposite pairs, as on hydrangeas and buddleja, cut straight across just above the pair.

Choose an outward-facing bud whenever you can. The new shoot will grow in the direction the bud points, so outward buds keep the centre of the shrub open to light and air. This matters on roses and fruit trees, where a congested middle encourages fungal disease.

When removing a whole branch, cut just outside the slightly swollen collar where it joins the main stem. Do not cut flush with the trunk, and do not leave a long stub. For heavy branches use three cuts: an undercut a little way out, a top cut just beyond it to drop the weight, then a final clean cut at the collar. This stops the bark tearing down the trunk.

The three Ds, then shape

Whatever you are pruning, start in the same order. Take out anything dead, damaged or diseased, cutting back into clean, healthy wood. Next remove stems that cross or rub against each other, as the wounds they create let in infection. Only then think about shape and size.

Work slowly and step back every few cuts to look at the whole plant. It is very easy to get carried away on one side. As a general rule, remove no more than about a third of a shrub’s growth in one year unless it is a type that is meant to be cut hard, such as buddleja or red-barked dogwood, which is cut to near the ground in early spring for the brightest winter stems.

Common mistakes

Pruning at the wrong time. The classic error is giving a spring-flowering shrub a tidy-up in autumn and losing all its flowers. Check first.
Blunt or dirty tools. Crushed, ragged cuts heal slowly. Sharpen blades and wipe them with disinfectant between plants, especially when you have been cutting diseased wood.
Using secateurs on thick stems. Bypass secateurs handle stems up to roughly finger thickness. Use loppers or a pruning saw for anything thicker.
Shearing everything into a ball. Clipping the outside of a flowering shrub with shears removes flower buds and leaves a dense shell of twigs. Thin from the base instead.
Cutting lavender and rosemary into old wood. Bare brown stems rarely sprout again. Trim only into leafy growth.
Painting wounds. Wound sealants are generally unnecessary and can trap moisture. A clean cut in the right place heals best on its own.

Troubleshooting

My shrub did not flower after pruning. You probably pruned off the flower buds. Next year, prune immediately after flowering, or for late-summer bloomers, in early spring.

It sent up masses of leafy shoots. That is the normal response to hard pruning. Thin the new shoots to the best-placed few in summer, and prune more lightly next time.

Branches are dying back from the cut. The cut was likely too far from a bud, leaving a stub. Cut back again to just above a live bud. If dieback spreads widely and you find white fungal sheets under the bark near ground level, read about honey fungus.

Leaves are coated in white powder after a summer trim. Soft regrowth in a crowded, dry spot is prone to powdery mildew. Open up the plant and water at the base during dry spells.

Once you have your timings sorted, pruning becomes a quick seasonal habit rather than a chore. If you are also planning to tidy up the borders, our guide to making compost explains which clippings to recycle and which to bin.