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Basics of fruit trees

Understanding Pollination

If you are planting a fruit tree, it is most probably because you would like to have fruit! However, if you don’t have a basic understanding of what pollination is and how it works, you may end up with fruit trees, but no fruit. So, what do you need to understand about pollination?

What is pollination?

To explain it in the simplest terms, every kind of fruit and nut begins life as a flower. When you see flowers on your trees in spring, these might be its future fruits! In order for it to transform into a piece of fruit, however, each flower must be fertilised with pollen from another flower. This is what ‘pollination’ means.
The pollen can be transported from one flower to another in a few different ways; the most common being by wind and by insects. Most fruit trees rely on insects, especially bees, to carry pollen from one flower to another. That’s also why bees are so important for the ecosystem as a whole

Bourdon pollinisant un arbre fruitier

Self-fertile and Self-sterile

So we know that a pear flower, to take an example, cannot transform into fruit unless it receives pollen from another flower. But can that pollen come from another flower from the same pear tree? The answer is that it depends on the tree.

Certain pear trees can fertilise themselves: that is, if a bee takes pollen from one flower and moves it to another flower of the same pear tree, that flower may be fertilised and grow into fruit. The tree is then called ‘self-fertile’.

In the case of many pear trees, however, the pollen must come from the flower of a different pear tree (known as a ‘pollinator’) – or else the flowers will not be fertilised and there will be no fruit. The kind of tree that cannot fertilise its own flowers, and needs pollen from a different tree, is called ‘self-sterile.’

So in practical terms, a self-fertile tree can produce fruit even when it is alone.
On the other hand, if a self-sterile tree is alone without a pollinator, it will produce flowers, but the flowers will never turn into fruit.

It is also worth noting that even when a tree is designated ‘self-fertile’ it will still give greater yields with a pollinator. In general, the more genetic diversity around, the more fruit your trees will produce.

What counts as a ‘pollinator’?

If you have an apple tree and a pear tree planted nearby, will they pollinate each other? Can one Collet apple tree pollinate another Collet apple tree?

In both cases the answer is no.

The first rule of pollination is that if a tree is self-sterile – like the Collet apple tree – then another copy of that exact same tree will not work as a pollinator. Since the two Collet apple trees are genetically identical, it just gives the same effect as having one bigger Collet apple tree. You need a different apple tree.

You should also know that two completely different types of fruit trees will not pollinate one another. Only an apple tree can pollinate other apple trees. A cherry tree will not pollinate a pear tree!

In general, what you need to remember is that in the case of grafted trees like apple and pear, or any specific fruit cultivar, you need a different tree of the same type to act as a pollinator.

In the case of trees that are grown from seed, such as hazelnuts or walnut trees, each individual tree is unique, and all are genetically different from one another. Therefore, you simply need two of the same kind of tree. For example, any two of the hazelberts we sell will pollinate each other, and any two American Chestnut trees will pollinate each other.

Pollinisation croisée des pruniers

Special case: plum tree pollination

Plum trees work slightly differently to most fruit trees in terms of pollination. Japanese and American hybrid plums are self-sterile, and cannot produce fruit alone.

Moreover (this is the main difference from other fruit trees), they are not good pollinators for one another. Even if you plant two different cultivars next to each other, you are unlikely to harvest any fruit. Instead, these hybrid plum trees need a wild plum tree to pollinate them: either the Canada plum (Prunus nigra) which is considered the best pollinator, or the American plum (Prunus americana) which also works well. So if you intend to plant plum trees, you must also plant at least one of these nearby, unless of course you already happen to have one. One wild plum tree is enough to pollinate up to around five grafted plum trees.

Some examples of pollination partners:

  • Southworth pear tree and Patten pear tree ✅ (Two different cultivars of pear tree)

  • Minnesota 447 apple and Sweet Sixteen apple ✅ (two different cultivars of apple tree)

  • Grenville plum tree and La Crescent plum tree ❌ (These plum trees can’t pollinate each other, they need a Canada Plum tree or American plum tree)

  • Hazelbert tree and long-beaked hazel tree ❌ (These are not compatible and can’t pollinate each other. You need either two hazelbert trees, or two long-beaked hazel trees)