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Frequently asked questions

My lilac is not flowering. Why?

  • Jardin botanique

Several reasons may explain why a lilac is flowering very little or not at all.

  1. Immature plant
    Like humans, plants must wait to reach a certain maturity before they are able to reproduce. Lilacs normally start flowering in their sixth year.
  2. Inappropriate pruning
    Lilac buds form at the end of branches during the previous year. If you want to remove wilted flowers, cut just below the flower head one to two weeks after blooming finishes. Pruning the ends of branches too severely or after the formation of buds will affect the next year’s flower production.
  3. Too much shade
    Lilacs need at least six hours of sun to flower properly. A lilac planted in the shadow of a building or a large tree will produce few flowers, if any.
  4. Over-fertilizing
    Plants given large amounts of nitrogen fertilizers produce more stems and leaves but a lot fewer flowers. Therefore, a lilac planted in the middle of a lawn that is fertilized on a regular basis may experience this type of problem.
  5. Biennial flowering
    Some lilacs are biennial – that is, they flower abundantly every second year.

To learn more, consult the Green Pages section on lilacs.

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