University of Maryland Extension

Lilac Pruning

Author: 
Carolyn Puckett
A lilac bush

Herman, D.E., et al. 1996. North Dakota tree handbook. USDA NRCS ND State Soil Conservation Committee; NDSU Extension and Western Area Power Administration, Bismarck. Courtesy of ND State Soil Conservation Committee

What do you do with an overgrown lilac?

The soothing scent of lilac blooms is a spring delight. However, an old-fashioned lilac ( genus Syringa) can grow up to 15 or 20 feet high, looking leggy and unattractive, and may bloom less as it ages. However, there is a way you can rejuvenate your lilac to look more appealing and encourage more blooms.

While it is possible to just cut down the entire plant to about six inches, you will not have blooms for a couple of years if you use this option. Instead, spread the pruning over a three-year period. The first year in March or April, cut out any damaged stalks first and then choose the oldest and biggest third of stalks to cut down to the ground. The second year cut another third of the old stalks to the ground. Of the new stalks that sprouted the prior year, select the most well placed shoots to keep and cut the remaining stalks down to the ground. Choose stalks to keep that are growing toward the outside rather than toward the center, and make certain the remaining stalks are not crossing each other. The third year you can cut down the remaining old stalks and any new stalks that you wish.

You can also head back the remaining stalks just above a bud immediately after blooming to encourage branching if you wish. You can continue with this pruning technique in future years to keep your lilacs attractive and blooming well.

For more information see http://umaine.edu/gardening/blog/2012/03/19/how-to-prune-a-lilac-bush/.

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