When should I prune a plum or cherry tree?

Late spring to midsummer, never winter — the silver leaf reason behind the rule, and what to do if the tree needs work outside that window.

Difficulty: beginner
Time: 20 min
Read: 5 min

Short answer

Prune plums, damsons, gages, cherries, apricots and ornamental prunus between late spring and midsummer — roughly May to July — when the tree is growing strongly. Winter pruning exposes wounds to silver leaf and bacterial canker, both of which can kill the tree.

This is the piece of garden timing that costs people whole trees. Silver leaf is a fungal disease whose spores are released mainly in the cooler, wetter months and which enters through fresh wounds. A tree pruned in June is growing vigorously, seals its wounds quickly and faces far fewer spores. A tree pruned in January is doing neither, and the infection travels down inside the branch, silvers the leaves and eventually kills the limb or the tree.

What you'll need

Sharp, clean secateurs and a pruning saw
Disinfectant for tools (optional)

Step by step

Prune only between late spring and midsummer.Roughly May to July for established trees. Some growers prune young, newly planted stone fruit slightly earlier, in spring as growth starts, to get the framework going. The hard rule is that nothing is pruned in autumn or winter.
Prune on a dry day.Spores travel and infect in wet conditions. A dry, settled spell in June is the ideal, and it also means the wound dries quickly.
Understand the disease you are avoiding.Silver leaf gives a silvery sheen to the leaves on affected branches, and a cut branch shows a dark stain in the wood. Bacterial canker causes sunken dead patches on the bark that ooze gum, with shot holes in the leaves. Both enter through wounds and both are much more likely from winter pruning.
Prune as little as possible.Stone fruit resent heavy pruning. Take out dead, damaged, diseased and crossing wood, open the centre a little for light and air, and stop. A well-shaped plum needs very little attention most years.
Cut cleanly and just outside the branch collar.The collar is the slight swelling where a branch meets the trunk, and it contains the tissue that seals the wound. Cutting flush removes it; leaving a stub means the stub dies and rots back.
Disinfect tools between trees.Particularly if there is any known silver leaf or canker in the garden or a neighbouring one. Wipe blades with a garden disinfectant or methylated spirit.
Deal with storm damage immediately, whatever the season.A torn branch is already an open wound and a hazard. Cut it back cleanly to a proper point straight away rather than waiting for June. An untidy tear is a far worse infection route than a clean cut.
Do not seal the wounds.Wound paints were once recommended specifically for stone fruit and are no longer considered useful. They trap moisture and can encourage decay. A clean cut at the right time of year is the protection.
Remove and destroy infected wood promptly.Cut affected branches back well into healthy wood — at least 150mm beyond any staining visible in the cut end — and take the material off site or burn it. Do not compost it and do not leave it lying around as a spore source.
Check for nesting birds before cutting in the season.May to July is peak nesting. The horticultural window and the nesting season overlap almost exactly here, so a careful check of the tree before starting is essential.

Tips

Ornamental flowering cherries follow the same rule as fruiting ones. They are the same genus and the same diseases apply, which is why so many suburban ornamental cherries decline after a winter tidy-up.
Plums fruit heavily and break branches under the weight. Thinning the fruit in June and propping heavy branches prevents a wound you then have to deal with.
If a plum tree needs major reduction, it may be better to accept the tree as it is, or to replace it. Stone fruit tolerate hard pruning badly at the best of times.

Common mistakes

Pruning with the rest of the fruit trees in winter — Apples and pears are winter-pruned and stone fruit are not. Doing the whole orchard on the same January afternoon is exactly how silver leaf gets in.
Pruning hard to reduce a big tree — Large wounds on stone fruit heal badly and invite infection even in summer. Repeated light pruning is the only good approach.
Leaving a torn branch until the right season — The tear is already an infection route. Clean it up immediately, whatever the month.
Pruning in wet weather — Spores are dispersed and infect in wet conditions, and the wound stays open and damp for longer.

If it doesn't work

Silvery sheen on the leaves of one branch

Cause: Silver leaf — Fix: Cut the branch back well into clean, unstained wood, in summer, and take the material away. If the whole tree is affected there is no cure.

Sunken dark bark patches oozing gum

Cause: Bacterial canker — Fix: Prune out affected wood in summer, well below the damage, and improve the tree's vigour. Severely affected trees are usually best replaced.

Gum oozing from the trunk with no dead bark

Cause: Gummosis — often a stress response rather than a disease — Fix: Check for waterlogging, drought or mechanical damage. It is common on stone fruit and not always significant.

Branch broken under the weight of fruit

Cause: Heavy crop, unthinned — Fix: Cut back cleanly to a good point immediately, and thin the fruit in June in future years.

Questions people ask

Can I prune a cherry tree in winter?

No. Stone fruit should only be pruned between late spring and midsummer. Winter pruning exposes wounds to silver leaf and bacterial canker when spores are abundant and the tree cannot seal quickly.

What if my tree really needs cutting back now, in December?

Wait unless it is a safety issue or storm damage. If a branch is broken or dangerous, cut it cleanly straight away — a clean cut now is better than a jagged tear all winter.

Does this apply to ornamental cherries too?

Yes. Ornamental flowering cherries, almonds and blackthorn are all in the same genus and susceptible to the same diseases. Prune them in summer, and prune them as little as possible.

How do I know it is silver leaf and not just dry weather?

Cut a branch that shows silvering and look at the cut face. Silver leaf produces a distinct dark stain in the wood. Leaf silvering without any staining in the wood is a different, non-fungal condition that usually recovers on its own.