Answer: Lilac and wisteria have different pruning requirements. If your lilac isn't blooming, perhaps it's getting too much shade, or not enough winter chill. Lilac's sometimes bloom best if they're slightly stressed in late summer. Hold back on water beginning now and your lilac should react by blooming next spring. The flower buds are produced at the ends of stems. If you prune now, you may prune off next spring's bloom. It's best to prune lilacs in late spring, right after the flowers fade. This will give the shrub all summer to develop new flowering stems.
Wisteria is pruned continuously during the summer months. Prune out the tips of all new shoots when they reach 12" long. Then in the winter, shorten the shoots again so that about 6 buds remain on each shoot. Cut away all suckers that appear at the base of the plant.
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