Q.French Lilac Pruning Advice
My lilacs were planted last year. They didn’t bloom but they have now got buds. Should I protect in winter and when should I prune?
Certified GKH Gardening Expert
If you are in the hardiness temperatures that were on the label the lilacs should be fine over winter. If you experience late freezes in the spring, you may want to protect them to save the flowers.
You can prune out dead or diseased wood in late winter, but save height reduction pruning till after the lilac flowers in the spring. Since they form buds in the previous summer, you don't want to cut those off.