A lilac's annual cut

To keep a lilac small without sacrificing bloom

Left: That's a "dwarf" lilac blocking that window.
                                                                      Annual pruning can keep it blooming at a more acceptable size (below).

You can keep a lilac's height under control, but still have lots of flowers. To do it you'll need loppers, pruners and fifteen minutes per shrub per year.

Every year, beginning in that year when the shrub first reaches the size you can allow:

  • Cut after the shrub blooms but before July.
  • Cut out the oldest wood -- every cane that's bloomed and is the height you've set as your upper limit. Cut those canes out right at ground level so you don't create a clutter of stubs. Stubs make pruning tougher every year and look unsightly, too.
  • Clip off all the spindly, weak suckers and those coming up at a distance from the center. The latter are not desirable unless you can allow the shrub to increase in width.
  • Thin the newest "keeper" canes. A lilac is most healthy and blooms best when it has only a handful of main canes; if there are more they will tend to be weakened by competition.
  • More photos of this process starting with a lilac that was allowed to grow too big: Prune a dwarf lilac.

Below, the loppers are nipping off an old cane at ground level.
A thicket of weak shoots is at "a."
At "b" is a cane that's coming up from roots well outside the plant's natural center. Take it out, unless you can allow the shrub to become wider.
At "c" is a sturdy one year old cane that is positioned for enough light and room to grow side branches; it's a keeper that will be of blooming age before it crosses your upper limit.

Use loppers or a small saw to remove the canes that have reached your height limit. Hand pruners are fine to remove excess new canes (left of the pruners) and thin, weak growth.

Learn one, learn a bunch of bushes!

Most spring-blooming shrubs can be pruned just this way. Go to What's Coming Up #86 for a shrub pruning guideline that explains when and how to prune over 60 kinds of shrubs.

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