One of our customers, M, got in touch with a fruit tree pollination question, asking about the difference between:
- Not self-fertile
- Partially self-fertile
- Self-fertile
M had bought a Summer Sun cherry tree, and noted that the RHS said she’s partially self-fertile, whereas we clearly state that she’s practically kinda almost self-fertile.
Other top garden sites like Garden Focused lean toward our nuanced assessment:
Summer Sun is sometimes described as partially self-sterile but will produce a good crop even as a standalone tree. It can almost be considered as fully self-fertile.
Pollination Testers Put a Bag On It
We don’t mean to be crude about this, but it comes down to putting a light, airy cloth bag over the flowers so bees and other bugs can’t get them.
When the flowers are full, a pollination tester would reach in the bag with a brush to twizzle around inside the flowers, simulating a bee moving the pollen, then tie up the bag again.
- Not self-fertile: No fruit will form
- Partially self-fertile: Fruit will form, but the crop will be small. The fruit are often normal, but might be poorer in flavour/texture/size, or misshapen
- Self-fertile: Normal size crops of good fruit will form. However, they can usually be improved further by pollination
We have not bag-tested Summer Sun ourselves, but the word on the street is that it’s at the high end of partial self-fertility, producing decent, but not big, crops of normal fruit with no partner.
Stella Cherries Are Everywhere..And So Are Other Pollination Partners!
Summer Sun is a smashing cherry, and it has the bonus feature of being a highly compatible pollination partner for Stella.
Stella is one of the most popular cherries in Britain, so chances are high that one is nearby!
So, in practice, Summer Sun works out to be “effectively self-fertile”, meaning you can have just the one cherry tree in your garden, and it should get the pollen top up it need from neighbours to crop really well.