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Why it’s best to prune your lilacs in early summer


Once a lilac bush is more than two years old, it requires annual pruning. The best time to grab your clippers and get to work is in early summer, after the flowers have bloomed and faded. Here’s what you should know about caring for lilac bushes and trees.


Why should lilacs be pruned in early summer?

Lilacs grow the next season’s flower buds in early summer, immediately after their flowers fade. If you put off pruning until later in the season, you risk removing the developing buds.

This is equally true for lilacs such as Bloomerang Purple that bloom twice a year. By pruning the bush after its initial bloom, you encourage new growth and more flowers in its second bloom in early fall.


Why is it important to prune lilacs annually?

If left to grow on their own, lilacs will eventually only flower at the tips of their uppermost branches. By pruning your lilac bush and creating a balance between older stems and new flowering shoots, you not only rejuvenate your plant but also make it more visually interesting.


How do you prune lilacs?

There are several techniques involved in pruning a lilac bush:

  • Get rid of dead, broken or diseased stems first, as well as any weaker branches. In addition, cut branches to prevent rubbing or crossing.
  • Remove old stems that are thicker than two inches. This prevents your lilac from growing too tall and encourages the growth of young shoots. The stems should be completely removed.
  • Manage sucker growth. Suckers are new shoots that grow around the base of the plant. A couple strong suckers can be retained to replace main branches, but all weaker suckers should be cut at the soil line so that they don’t steal away nutrients.

Finally, there are a few of rules of thumb to follow when pruning lilacs:

  • Trim mature lilac bushes so that they remain within 6 to 8 feet.
  • Aim to have 10 to 12 main stems, each of them 1 to 2 inches thick.
  • Never prune more than one-third of the bush.
  • Create a balance of older stems and new flowering shoots.


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For more plant management tips and for professional plant and tree pruning, trimming and restoration services, trust the team at ArborCare. Contact us today to find out more about our tree care services or to schedule an appointment in or near Calgary, Edmonton, Kelowna or Winnipeg.

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