Understanding Pollination Groups
What is pollination?
To produce fruit, a flower must first be fertilised. After pollination and fertilisation, the flower’s ovary develops into the fruit. Pollination usually happens thanks to insects such as bees, flies, beetles and wasps. In theory, you could do it yourself with a small brush, but it’s far easier (and more reliable) to leave it to the insects. So normally, you need at least 2 compatible trees to ensure pollination, and fruit.
Self-fertile trees
Some fruit trees are self-fertile, meaning they can pollinate themselves and still produce fruit. Self-fertile varieties often produce a better crop when they have a compatible partner tree nearby.
Triploid trees
To make things more complicated, some fruit trees need two other compatible, and different, varieties nearby to produce fruit.
How Close Should Trees Be?
Ideally, fruit trees should be planted within 18 metres (around 55 feet) of one another to ensure good pollination – ie this ensures bees and other insects can travel between the trees. That said, in towns and cities, it’s likely that pollinating insects will visit nearby gardens too — so your tree might still be pollinated even if you don’t plant companions yourself. Bees can travel over two miles, but it is always best to plan for lazy bees and ensure you have compatible trees nearby!
Flowering Groups Explained
Pollination only works when trees flower at roughly the same time. They also need to be the same species (ie an apple can’t fertilise a plum). Tree nurseries therefore group fruit trees into flowering groups based on when they bloom. Fruit trees can be pollinated by a partner tree in the same flowering group, or adjacent flowering groups. Ie, an apple variety in group 2 can be fertilised by a tree in group 2, but also in groups 1 or 3.