Not mature enough? Too much nitrogen?

If it is now 10' tall, it is certainly not Bloomerang, which is a complex hybrid that only gets about 5' tall max.

Overly rich soils, excessive (nitrogen) fertilization and late spring freezes can all impact flowering. But we are only guessing at best unless we can confirm the ID of the plant in question. Photos?

Here is the lilac. Re maturity, isnt a decade long enough??

' I picked it up from a roadside stand '

That's cool. I didn't know people still did that.

Those leaves in the picture look more like S. vulgaris. But it's a wonder, if that's what it is, why there has been no blooms.

My syringa reticulata 'ivory silk' started blooming on its 7th year in the ground.

I just took these pictures; they are longer and larger than my regular lilacs.

And of course, grows in a Tree form.

This was last summer. Third week of June.