All multi-stemmed shrubs, including lilacs, can and should be "renewal pruned, that is, the largest, oldest, thickest stems are cut as near to ground level as possible, leaving behind the youngest growth, which will produce more flowers (next year)_ anyway. The use of hedge trimmers and the like on multi-stemmed shrubs is classic monkey see-monkey do business. That tool is for clipped or sheared hedges, not informal shrub borders like lilacs are used for. Ouch. But it happens everywhere. Shrub care and pruning are easily the weakest, most poorly-understood facets of landscape maintenance...in the country.

+oM

Well those turned out upside down. Sorry! Hopefully you can still tell what's going on..

Sell the hedge trimmer. They will survive, but it won't be gorgeous for a couple of years. I would take my pruners and cut some/ f the old wood in the middle, and all the dead wood. Mulch them and hope for the best.

They have been trimmed as a formal hedge in the past. So that is why they didn't bloom - flowerbuds have been constantly cut off. Far from being overgrown they have been persistently thwarted in their attempts to grow to their natural size and shape. If you want them to bloom you will need to accept them being taller and less formal in shape.

Miss Kim unplugged...

Nice illustration of my point, catkinZ8a.