no plums

I have exactly the same problem with an apple tree bought last year and which produced a crop for me.   It has blossomed this year, but no apples are developing.    I saw an apple grower interviewed on the TV News, and he said it is a disastrous year for fruit.     Long established apple trees that he usually gets about 500 apples from will only be bearing about 50 apples each this year.    All down to the spring we had, according to him.    The wrong weather when the blossom was out meant a lot of it was destroyed, and not enough pollinating insects at that time either.   

Now I am sure some gardeners will add to this thread that they are having a bumper crop of apples and plums! 

We bought a 2-in-1 plum tree about 4 years ago. It's half damson and half greengage, grafted on to one rootstock.

It has grown well but stubbornly refused to flower at all. It's nota pollenation problme, there simply are no flowers.Then this year it produced two tiny flowers together. One of these has set, so we are looking forward to our first plum!

I still don't know what we're doing wrong, I gave it a good feed of potash early in the year. I've pruned it a bit now, but am not sure whether I've done this right. If anyone has any ideas on how to encourage it to blossom, please tell me!

Move it to a warmer climate!  I'm sure the lovely warm weather we had in May made the trees think it was June, then we've had a very wet June (so far) so the poor trees think we're back in March.  No wonder they're not producing!