Rejuvenation Pruning for Japanese Lilac Trees

First Year

• Remove about one-third of the largest branches on Japanese tree lilacs grown as shrubs, cutting back to ground level. On specimens grown as a small tree, remove one-third of the largest lateral branches, evenly spaced in the tree's canopy.

Second Year

• Prune out another third of the oldest branches in the same manner as the first year. Head back vigorous new shoots that grew as a result of the previous years' pruning, making them various lengths and removing approximately one-third to one-half of the length of the new growth.

Third Year

• Cut out the remaining old branches in the third year, exactly the same as you removed them in the previous two years. Cut back vigorous new growth to about one-third to one-half its height.

One-Shot Rejuvenation Pruning

• The Syringa species is one of a few species of shrubs that responds well to a drastic rejuvenation pruning technique. The plant is cut back entirely to just above ground level. It will respond by putting out a lot of vigorous new growth, but will most likely not flower until the following year.