Why thinning pays off

If you have ever watched a branch sag under a crop so heavy the wood creaks, you already know why thinning matters. A tree sets far more fruitlets than it can bring to a decent size. Left alone, those crowded clusters compete for water, sugars and nutrients, and the result is a crop of small, hard, disappointing fruit rather than a modest harvest of apples you actually want to eat.

Thinning also protects the tree itself. Overloaded limbs snap in summer gales or bend and stay bent, ruining the shape of a trained tree for years. Heavy crops exhaust the tree's reserves and encourage it to take the following year off — the familiar biennial bearing of many older varieties. Removing a proportion of fruitlets in a heavy year evens out that rhythm and lowers pest and disease pressure, since codling moth larvae and brown rot spread easily between fruits that touch.

When to thin

Timing matters more than technique. Most apples and pears shed a proportion of their young fruitlets naturally in early summer, in what gardeners call the June drop — it often runs into early July. Wait until that has finished, then thin what remains.

The signal is size. Fruitlets should be roughly the size of a marble, about 2–3 cm across, with the stalk still firm enough to handle. Thinning earlier, in late May, risks the tree shedding more fruit afterwards and leaving you with too light a crop; thinning in August is largely a waste of effort. Choose a dry, mild day, as damp conditions encourage fungal spores to enter small wounds.

How much fruit to leave

Spacing is the simplest guide, and far easier to judge than counting leaves.

• Dessert apples: one fruit roughly every 10–15 cm along the branch.
• Large culinary apples such as Bramley: 15–20 cm, as each fruit needs room to swell.
• Pears: 10–15 cm, and always break clusters down to a single fruit.
• Plums and gages: 5–8 cm for dessert varieties, a little wider for large cookers.

Where fruit grows in a cluster of two to five, keep the best one and remove the rest. Choose the largest, cleanest, best-shaped fruitlets, with no blemish, no moth entry hole and no sign of scab. As a rough check, many growers aim for around 40–50 healthy leaves to support each fruit left on the tree. On a light-cropping tree, thin gently or not at all; on one carrying a huge set, be brave, because the fruit you leave will reward you.

Thinning apples and pears step by step

You can thin with your fingers, but a pair of small, sharp scissors or thinning snips is kinder to the tree and much faster on a big old tree.

• Work from the outside of the tree inwards and from the top down, so you can see what you are doing.
• Cut the stalk cleanly near the fruit, leaving the short stub attached to the spur. Never pull or twist fruit off, as this tears the spur and can remove next year's flower buds with it.
• Reduce every cluster to one fruit before you worry about spacing along the branch.
• Take damaged, misshapen and undersized fruitlets first — they are the easiest to part with.
• On apples, some gardeners remove the central "king" fruit of each cluster and keep a well-shaped lateral instead, partly because the king fruit is often misshapen and partly because codling moth females favour it. If it looks perfect, keeping it does no harm.

Thinning can feel brutal. A branch that looked generous in June will look positively sparse afterwards, and that is exactly right.

Plums, cherries and other top fruit

Plums set heavily and benefit just as much, especially if you want fruit for eating rather than jam. Space dessert plums 5–8 cm apart and remove any fruit with a small hole or gummy droplet at its base, which usually means plum moth. Thin plums by hand rather than reaching for the secateurs; plum wood is prone to silverleaf, and every pruning cut is a possible infection point.

Sweet cherries are rarely thinned in British gardens — the fruit splits easily and the birds will take their share anyway. Where a young cherry is badly overloaded, removing a few clusters by hand is enough. Quinces, medlars and mulberries generally look after themselves.

Looking after the tree afterwards

Thinning is only half the job. Give the remaining fruit the best chance of swelling by watering thoroughly in dry spells from July onwards, when the fruit is filling out — a good soak once a week beats a daily sprinkle. A mulch of well-rotted compost or manure around the roots, kept clear of the trunk, helps hold that moisture in.

Clear the thinned fruitlets off the ground and put them in the bin rather than the compost heap; any carrying moth larvae or rot will only cause trouble next year. If branches still look laden in August, prop them with a stout forked stick padded with cloth rather than letting them bend. A very young tree in its first two or three years is better off carrying no fruit at all, so strip it completely and let its energy go into roots and framework.

Do this for a season or two and you will notice the difference: fewer apples, yes, but each one heavier, better coloured and far more satisfying to pick.