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Lilac Pruning

Discussion in 'Landscape Architecture and Design' started by mikesjumpingin, May 3, 2003.

  1. mikesjumpingin

    mikesjumpingin LawnSite Member
    Messages: 101

    I suppose the best time of year for lilac pruning is Feb. or during dormancy, but I have a customer that wants a dwarf trimmed now.

    Usually I prune so sun can get in, but I once pruned my own lilac in February and got no flowers until the next entire season, and I've heard this happens to guys who've top them.

    What is the best way to do lilacs, and can someone refer me to a good book on pruning? I've found the little Stihl pruning guide (free) to be helpful for a beginner like me, but only in a general sense.


  2. kris

    kris LawnSite Bronze Member
    from nowhere
    Messages: 1,578

    The ideal time to prune most plants is during the dormant season prior to the start of new growth. Flowering shrubs may be an exception..... I say may because some hort specialist believe the effect of the shrub's structural branching characteristics is more important than its flowering effect in the total landscape design. Therefore, it may be better to prune all flowering shrubs in early spring before new growth starts. Some bloom will be sacrificed by this method.
    Shrubs that bloom in spring may be pruned after flowering. Late flowering shrubs that bloom on wood produced the same year can be pruned before growth starts in the spring.
    Either method can be recommended. One has to determine for himself the time to prune deciduous shrubs.

    I prune lilac after they flower.
  3. Turfdude

    Turfdude LawnSite Bronze Member
    Messages: 1,899

    Just remember that if you prune heavily, that it generally will take 3 years for a lilac to bloom again.
  4. CMerLand

    CMerLand LawnSite Senior Member
    Messages: 393


    As a general rule of thumb you will prune spring flowering shrubs after they bloom. These include forsythia, azalea, rhododendren, lilac etc.

    Now with this lilac what are your goals? Renovation, rejuvination or just to get the plant from blocking the windows? Each situation requires different techniques. Lilacs and similar shrubs do not flower as profusely as they age. By rejuvination, you prune out 1/3 of the oldest wood each year for three years to allow the younger more vibrant wood inside to become established. After three years you have a new plant with young healthy wood and without dramitacally changing the appeareance all in one shot.

    Renovation of shrubs such as some spirea and forsythia, involve cutting the entire plant back severely to allow the young growth to grow to form new bushes from the new sprouts that will grow up from the base stems and root system. If done in early spring you will lose the bloom that year but will have a new vigorous plant the following season.

    Best of luck

  5. mdvaden

    mdvaden LawnSite Bronze Member
    Messages: 1,946

    Lilac, if I recall this correct, blooms this year, on the new growth of last year.

    Forsythia is like that too.

    Other shrubs will bloom on this years new growth.

    You need to do a search on Google, or look in a book, to determine that for each shrub.

    Dormant pruning benefits are so minor and undetectable, that it is safe to prune all 365 days per year, provided you stay moderate - nothing radical.

    Even if dormant pruning was significantly better, the general public would get "blown out of the water" financially, if pruning and tree services had to shift an entire year's income needs into only 2 or 3 months.

    I have pruned extensively for over 20 years, all year long, without evidence of health problems.

    Of course there are current experts teaching about pruning and bud formation - and what they say is true, but its insignificant when looking at the big picture. And the casualties are not there to justify major timing transitions.

    The key is moderation.

    So on the lilacs, either prune off very few of the ends remaining from last year, or, wait for the plant to bloom, then prune it.
  6. mikesjumpingin

    mikesjumpingin LawnSite Member
    Messages: 101

    Practical info!

    I noticed the research reflects a lot of ideal/best times, but those of us working need to factor severity of timing vs. practical scheduling. Good points, everyone.

    Thanks guys!


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