Syringa vulgaris
By Shthompson
Suffolk,
United Kingdom 
I planted this lilac last year and it flowered well, I didn't do anything to it after flowering and now find that it hasn't flowered at all this year. Should I have pruned it? But not having done so what can I do now?
28 May, 2008
Answers
I don't think you will do any harm by pruning it now - but not too hard, If it had flowered, this would be the correct time, after all.
28 May, 2008
Agree both. Unless it's in alkaline soil.
29 May, 2008
I`ve read that you shouldnt prune in its first year, but can after that, and it will recover from hard pruning.
29 May, 2008
I believe lilacs flower best in a sunny position. This year ours had flowers only on the unshaded side, it has gradually been overshadowed by nearby conifer hedge and wild cherry trees,. We have cut back the conifers and cherry trees to give it more sunlight and hope this and judicious pruning will help it have more flowers next year.
29 May, 2008
You should have pruned it
28 May, 2008