Many pear trees need to be cross-pollinated with another variety to make fruit.
To help you choose the right trees to pollinate each other, we have put them into 4 groups in the colour coded table below.
It's very easy: a pear tree can cross-pollinate with any tree in its own group or a group next to it on the table. So, it works like this:
|Name||Use||Harvest||Pollination Group||Cross Pollinates With Which Groups?
|Louise Bonne of Jersey||Eating||Mid||A||A,B
(Except Williams Bon Chretien)
(A poor pollinator for other pears)
(Triploid - cannot pollinate other trees)
|Williams bon Chretien||Eating||Early||B||A,B,C
(Except Louise Bonne of Jersey)
|Doyenne du Comice||Eating||Mid||C||B,C,D
|Humbug||Eating / Cooking||Late||C||B,C,D|
|Invincible||Eating / Cooking||Mid||C||B,C,D|
(Except Doyenne du Comice)
|Hellens Early||Eating / Cooking||Mid||D||C,D|
More Facts About Pear Tree Pollination:
For two pear trees to cross-pollinate each other, the flowers of both trees need to be open at the same time.
The groups above refer to each tree's flowering period: Group A is Early, Group B is Mid-Season etc.
Because the flowering periods overlap, trees in each of the 3 groups can cross-pollinate trees in the group or groups next to them
Flowering Dates vs Harvest Dates:
Your pear tree's flowering group is not connected with the date when the fruit ripens.
You will notice that all of the early and late cropping pear trees are in the mid season flowering group, while all of the early and late flowering trees crop in the main season.
Self Fertile Pear Trees:
The fact is that many pears aren't very good at pollinating themselves.
Conference and Concorde are truly self-fertile, while trees such as Louise Bonne of Jersey trees are partially self-fertile, which means they will carry some fruit without another variety to pollinate them, but their crops will be much larger if there is.
Not all is lost if you do not have room for two pear trees however. Pollination is done mainly by bees who fly enormous distances on their pollen "collection" rounds. As long as a neighbour within a few gardens has a compatible pear (which includes ornamental pears) you should be fine.