How to prune garden shrubs

Video by the Royal Horticultural Society. This guide draws on “How to prune spring flowering shrubs” from the Royal Horticultural Society’s Grow at Home series. The RHS is the UK’s leading gardening charity and their pruning guidance is about as authoritative as it gets. This particular video is a clear and practical introduction to the timing and technique that trips up most gardeners with spring-flowering shrubs.

1. Understand old wood and new wood

Most shrub pruning mistakes come down to not knowing which type of wood a plant flowers on. Spring-flowering shrubs — forsythia, philadelphus, weigela, deutzia — flower on wood produced the previous year. Prune them in winter and you remove all those buds. Prune them straight after flowering and the plant has a full season to grow fresh shoots that will carry next year’s display.

Summer-flowering shrubs — buddleja, lavatera, hardy fuchsia, many hydrangeas — flower on wood produced in the current year. You can prune these hard in late winter without losing a single flower, because all the flowering growth is still to come. That said, always check which group your specific plant falls into before reaching for the secateurs.

2. Use the right tools and keep them sharp

Good secateurs are the main tool for most pruning. They should cut cleanly with a single action, without tearing or crushing the stem. Blunt secateurs cause more damage than clean cuts and create entry points for disease.

For thicker stems — anything over about 12 mm in diameter — use loppers. For larger old wood, a pruning saw is cleaner and safer than trying to force loppers through something they were not designed for. Wipe blades with a disinfectant wipe between plants, particularly if you are working near any diseased material.

3. Make cuts in the right place

Always cut to just above a bud or a sideshoot, at a slight angle so water runs away from the bud rather than pooling on the cut surface. The cut should be close enough to the bud that you do not leave a dead stub, but not so close that you damage the bud itself. About 5 mm above is roughly right.

For thicker stems, the cut itself is less critical in terms of angle, but do remove the stem completely rather than leaving a short stub. Stubs die back and become an entry point for disease and rot.

4. Prune spring-flowering shrubs immediately after flowering

The timing on spring shrubs is tight. Once the flowers fade, that is the signal to prune. Do not wait until autumn or winter — by then the plant has already set next year’s buds and you will lose them. Cut out the oldest, woodiest stems completely at the base, and shorten the flowered shoots back to strong sidepairs.

This might feel like you are cutting too hard, particularly on a large forsythia or mock orange that has been left unpruned for a few years. To be fair, renovating an overgrown shrub is a multi-year project. Bring it back gradually rather than taking everything off in one go, or you risk weakening the plant badly.

5. Prune summer-flowering shrubs in late winter

Buddleja and similar summer-flowering shrubs respond brilliantly to hard pruning in late winter — February and March in most parts of the UK. Cut stems back to two or three pairs of buds from the base. It looks severe. In a few weeks, the plant throws out vigorous new shoots that carry the summer flowers.

Hydrangeas need a bit more care. Mophead and lacecap types flower on old wood (like spring shrubs) so prune lightly in spring, cutting spent flowerheads back to the first strong buds. Panicle hydrangeas flower on new wood and can be pruned hard in late winter. Worth identifying which type you have before cutting.

6. Remove the three Ds: dead, diseased, and damaged wood

Whatever time of year, dead and diseased wood comes out. Do not leave it to improve on its own — it will not. Cut back to clean, healthy wood, removing the affected section entirely. If a branch has died back, cut until you see white or cream-coloured wood at the cut surface.

Crossing branches that rub against each other also come out. Rubbing creates wounds that invite disease. Keep the centre of the plant open enough for air to circulate freely. A congested shrub is a shrub building up trouble for itself.

7. Feed after pruning

Pruning stimulates new growth, and new growth needs fuel. Apply a balanced general fertiliser around the base of the shrub after a hard prune, and water it in. A mulch of garden compost on top of the soil around the plant will help retain moisture and give the new roots something to grow into.

Do not overdo it with nitrogen-heavy feed, particularly late in the season. Lots of soft, sappy growth in late summer is more susceptible to frost damage and to powdery mildew. A balanced feed in spring is generally the sensible approach.

When to call a handyman

Richard can help with general garden tidying, hedge trimming, and getting overgrown shrubs back under control where access is straightforward. For very large shrubs or trees close to structures, a qualified tree surgeon is the right person to call. Knowing the difference matters — and most handymen will tell you honestly when something is outside their scope.