Q.plum tree not blooming
My plum tree is about 4 years old and has only ever had blossoms the first year it was planted and produced a golden plum. Is there anything I can do to promote its ability to produce blossoms?
Plum trees begin to bear fruit in earnest when they are 3-6 years of age. So you are right in that window where your plum tree is "just" getting mature enough. So your expectations may be too high at this point. Does your tree look healthy otherwise?
Have you pruned your plum tree? Pruning will encourage flower bud and fruit growth.
Do you fertilize your plum tree? They should be fertilized annually. Fertilizers higher in phosphorus will help with blooming and fruiting.
I would recommend you read the following article which discusses possible reasons for plum trees not fruiting: