What is thinning, and why is it necessary?
Gardeners often complain that despite their fruit trees producing copious blossom and fruitlets, the final fruits turn out to be disappointingly small and riddled with pest and disease problems.
Fruit trees produce more fruitlets than they can realistically ripen. In the wild, many of these are lost to pests or diseases. In garden cultivation, with intensive management of pest and disease problems and with the development of resistant cultivars, this natural thinning may not occur to the same extent.
Many healthy fruit trees drop fruit naturally in early summer. But even after this ‘June drop’, too many fruitlets can remain on the branches, resulting in a final crop of disappointingly small fruits, and in the spread of fungal diseases and pests between fruits that are so close as to be almost touching.
Deliberate thinning of the fruitlets can produce better-sized, ripe and healthy fruits, albeit in smaller numbers. Thinning allows sunlight and air to penetrate the branches, so improving evenness of ripening, and discouraging the spread of disease.
When to thin
We recommend midsummer, i.e. around July. Experienced growers tend to thin before this, in early summer, as this results in the greatest increase in size of those fruits remaining. But for the amateur or inexperienced gardener, it is best to wait until after the natural June drop, otherwise there is a risk of being left with nothing.
Apples
Overcrowded fruitlets Slightly thinned branch King fruit in a clusterThese apple fruitlets are overcrowded. There would be no room for all of these apples to develop to maturity.
This branch has been thinned a little - just enough to identify the separate clusters within the crowded fruits.
The ‘king fruit’ of the cluster is indicated. This is usually centrally placed, may be larger and more irregularly shaped than the other fruits, and often has a shorter, thicker stalk (petiole).
Small, thinned cluster Final thinning and spacingThe king fruit and its stalk (petiole) can be seen more clearly in this small cluster. This branch has been thinned to a very generous spacing, as would be done with a large cooking apple, aiming for one fruit every 15-23cm (6-9in).
Dessert apples can be thinned less severely, aiming for one or two fruits every 10-15cm (4-6in), depending on whether they are small- or large-fruited cultivars. Thinning can be done using secateurs, or with a firm tug between thumb and forefinger.
Pears
Pears can be prone to over-bearing; thin clusters to two fruits (one for a small cordon), 10-15 cm (4-6in) apart.
Peaches and nectarines
Thin peaches to one every 10cm (4in) when the size of a hazelnut, then again to one every 20-25cm (8-10in) when the size of a walnut. Thin nectarines to 15cm (6in) at walnut size.
Apricots
Apricots are less prone to over-bearing; thin only if the crop is excessively heavy, to 5-8cm (2-3in) apart when hazelnut sized.
Plums
Thinned plum branch Plums have a particular tendency to overcropping, so thinning is vital. Heavily laden branches may need additional support with stakes and/or ties even after thinning to prevent them snapping.
Thinnings can be plucked off between thumb and forefinger.
The breadth of the splayed hand is a useful rough guide to spacing. An ‘average’ hand is 15-16cm (approx. 6in) in breadth when the fingers are splayed. (Those with larger or smaller hands can adjust their measure accordingly).
The aim is to leave one fruit every 5-8cm (2-3in), or a pair of fruits every 15-16cm (approx. 6in), i.e. a pair of fruits at every hand’s breadth, as in the image.
Maya Albert
