I was given a young plum tree three years ago as a present from colleagues. It had perhaps two tiny plums.
Last year, after being planted for several months, the little tree was a mass of blossom in late April/early May and produced literally pounds of small sweet plums.
This year it has produced a lot of leaves, but not one single flower. Although we have fed it, and watered in dry spells, and it looks healthy, we don't understand why there is no blossom this year. It is self pollinating, but I cant recall the name of the plum, alas!