[Kleftiwallah]

How can I assist the blossoms to set, would a fine water spray help?

Cheers,  Tony.

[gobs]

I don't think so. Wildlife should do it.

[Middlesexbloke]

Loads of bees around already due to the warm weather. If in doubt, you could 'tickle' each blossom with a very fine artists brush. I do that with my apricot tree and it helps with fruit set but only practical if the tree isn't too big!

[8doubles]

A quick google says sweet cherries need cross pollination so diy is a waste of time.