Some of you may have seen those overly-complicated looking pollination charts for fruit trees.

The reasons are rather simple, and hopefully the following explanation should give you a better understanding of what is going on in those pollination charts.

There are four things going on here.

Most types of fruit trees cannot pollinate themselves; you need two different varieties of the same fruit tree. This is nature’s way of trying to prevent the same fruit tree from pollinating itself, to increase sexual variety. That being said, there are often certain varieties that can pollinate themselves. One example of this is the sweet cherry variety Stella, which was originally bred from using irradiated pollen in the 1950’s. Then there are some varieties of fruit trees that may be capable of pollinating themselves, but have much more successful pollination rates if pollinated by another variety. Supposedly the Pear 'Conference' is one of these.

Second, some groups of cultivars are closely related to each other. An example of this among the sweet cherry varieties are Bing, Emperor Francis, and Kristin. So Bing cannot be pollinated by Emperor Francis, just as it cannot be pollinated by another Bing tree.

Third, some fruit tree varieties can be pollinated by any other variety but are just terrible at pollinating other varieties. So the pollination mostly goes one way. An example of this is the Pear known as “Pound” (‘Belle Angevine’).

Lastly, different varieties may have different flowering times. One variety is not going to be able to pollinate another if the flowering times are too far apart.