How and When to Prune Lilacs for Bigger Blooms

Updated on May 16, 2017
Anthony Altorenna profile image

I like spending time in the garden, around the house, in the workshop, and fishing. Many of the projects in my articles are originals.

Spring is popping with big, beautiful, purple lilac blooms.
Spring is popping with big, beautiful, purple lilac blooms. | Source
Purple Lilacs in Bloom
Purple Lilacs in Bloom | Source

Big, beautiful, and fragrant flowers makes the lilac one of the most recognizable and well known of the flowering shrubs. Blooming in spring, the burst of color fills the air with their floral scent to help awaken the garden after the long winter.

Lilacs are hardy, long-lived plants that are easy to grow. Healthy and well-pruned shrubs bloom proficiently in late spring, filling the garden with their sweet scent and color that attract the attention of hummingbirds, bees, butterflies, and gardeners. While purple flowers are the most common colored blooms, horticulturalists have developed many different cultivars with flowers in white, pink, yellow, and burgundy.

Lovely Lavender Lilac Blooms
Lovely Lavender Lilac Blooms | Source

Growing Lilacs

Lilacs are a landscape staple for several reasons: they are easy to grow, they bloom proficiently, and even after the flowers fade, the shrub looks good in the landscape.

  • For optimal blooming performance, select a planting site that receives full sun. Fertilize in early spring with an all purpose 10-10-10 fertilizer, and then reapply the fertilizer again after the blooms fade.
  • Established plants are very hardy but newly transplanted specimens may require watering during periods of drought.
  • Lilacs are easy to transplant and propagate from the many new shoots that sprout from the base of established plants each spring. Use a sharp spade to dig down and around the shoot, creating a small root ball while severing the shoot from the parent plant. Transplant the new little plant into a sunny location and keep it watered well until it becomes established.

My grandfather loved growing lilacs, and his pride and joy was a robust plant that exploded with white flowers every spring. Thanks to his gardening skills and generosity, I have several plants growing in my yard that are the direct descendants of his plants. My grandfather is gone now, but I am reminded of him every spring when 'his' lilacs are in full bloom. Thank you, Grandpop!

If these blooming shrubs have any drawback, it's that their flowers tend to fade quickly. By planting several different varieties with different flowering times in early, mid, and late spring, gardeners can extend the blooming season. Careful and selective pruning helps to keep a plant healthy and will increase blooms for the following year, but pruning a lilac incorrectly or at the wrong time can reduce or eliminate those wonderful spring flowers.

Here are a few tips for pruning lilacs to get the most blooms every year.

When and How to Prune Lilacs

Beautiful White Lilac Flowers
Beautiful White Lilac Flowers | Source

When to Get the Clippers

There is a right time of year to prune a lilac, and there are also lots of wrong times for pruning these flowering woody shrubs. They grow quickly and they can grow quite tall so they need an annual trimming to retain their shape and to keep them blooming consistently every year. The only right time to prune these shrubs is just after the last of the flowers fade away in late spring. Prune lilacs in late spring to remove the dead flowers and broken or damaged limbs before the plant sets out its buds as it prepares for next year's blooms.

Deadheading the spent blooms and removing the spent flowers also prevents seeds from developing for the next generation, and redirects the plant's energy towards producing those new buds that will form flowers next spring. Deadheading and removing the old flowers is an important step towards ensuring that your shrub will bloom proficiently year after year.

Lilacs begin to form next year's buds shortly after this year's flowers finish blooming. To avoid cutting away next year's flowers, it is very important to trim them right after they finish flowering. The new buds are hard to see, but they begin to form in the late spring. The trick is to prune and shape the bush within the first few weeks after the plant finishes blooming, but before it starts growing new buds. Waiting too long to trim your lilac means either putting off the chore until next year, or risk cutting off the flowers for next spring before they even get the chance to grow.

How to Prune

A well-shaped lilac needs annual pruning to retain the rounded form that most gardeners desire, and to help control the overall height of the shrub. Depending on the variety, these hardy growers can reach up and over 20 feet in height. And since most of the buds form on the tips of the branches, the flowers of a tall lilac will bloom near the top of the plant—out of reach and perhaps beyond where the flowers are easily seen and enjoyed.

While your plants are blooming this spring, look closely at the shape of the shrub. Also, take note of where the plant is sporting most of its blooms. Lilacs flower at the tips of its branches, and the areas that receive the most sunshine will boast the biggest and brightest flowers. After the blooms fade and die off, selectively prune the branches to control the height and to re-form its shape. In most cases, lilacs do not require much pruning beyond deadheading and removing a few select branches to improve the shape and appearance of the shrub.

Healthy lilacs sprout new suckers from the ground each year. Prune out some of the suckers, and remove any crossing branches or leggy limbs. Remember that they flower on the older stems, making it important to remove only those limbs and branches that are necessary to maintain a nicely shaped and well proportioned shrub.

Over time and as the plant ages, the interior may become congested with a tangle of older limbs. Lilacs will bloom reliably for years with minimal care, but some older plants may become less productive. To reinvigorate an older plant and to encourage more blooms, remove about one third of the plant each year by cutting the selected shoots and branches back at ground level. Severe pruning encourages new growth, but since lilacs flower only on old wood, it can take several years before the lilac blooms proficiently again after a severe pruning.

This well shaped lilac blooms profusely every spring.
This well shaped lilac blooms profusely every spring. | Source

What Is Your Favorite Color of Lilac?

What Is Your Favorite Color of Lilac?

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Will Lilacs Grow in Your Garden?

USDA Plant Hardiness Zone Map

The USDA Plant Hardiness Zone Map is now interactive: Search using your zip code or click on your state to find your exact plant hardiness zone for your area.

USDA Plant Hardiness Zone Map
USDA Plant Hardiness Zone Map | Source

Will You Have Lilacs Blooming in Your Yard This Spring?

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The Right Pruning Tools

For lilacs and other shrubs:

Long handle loppers for extra reach
Long handle loppers for extra reach | Source

A Pair of Pruning Shears

Every spring means lots of yard work including shaping and thinning out the shrubs, pruning and limbing up trees, cutting out dead and broken branches damaged by the ice and snow, as well as working on a list of new spring projects.

Using the right tools makes pruning a more enjoyable task. Sharp, quality tools not only makes the job easier, but sharp blades slice cleanly for cuts that heal quickly. The three tools that I use for nearly every pruning job are the bypass shears for deadheading spent blooms and clipping off the ends of thin branches, long handled loppers for reaching deep into the shrub and for cutting through thicker branches, and a pruning saw for limbs and clearing out dead wood.

Bypass Loppers

The bypass blades on shears and loppers cut cleanly through live branches with very little effort. A pair of bypass shears slice cleanly for collecting fresh flowers, as well as making quick work of nipping off spent blooms. The long handles on give plenty of reach for thinning out shrubs, limbing up trees and reaching deep into the brambles for cutting shoots off at the base.

The lopper's cushioned handle grips are comfortable and slip-free, and the bright orange label helps the tool standout and made it easy to find when I carelessly left it on the ground. The long handle length also gives the tool some extra leverage for slicing through branches.

Bypass loppers are designed for pruning and cutting live branches up to 1 1/2" thick. They are not designed to cut deadwood, which is extremely dry and hard and can damage the cutting edge or even bend the blade. For old dead wood, use an anvil style cutter. If you trim a lot of shrubs and trees, you need both a bypass cutter for living branches and an anvil cutter for dead wood.

A Pruning Saw

For larger diameter branches, the aggressive teeth of a pruning saw rips through wood quickly and with little effort. I use a folding pruning saw so that I can safely close the blade for carrying around the yard.

Blooming Lilacs in our backyard.
Blooming Lilacs in our backyard. | Source

© 2012 Anthony Altorenna

Tell Us About the Lilacs in Your Garden

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    • profile image

      MS 8 months ago

      Can you suggest some very fragrant purple lilac hybrids that don't need the low chill factor and can grow in the south (N.C.).

    • profile image

      Mlg 19 months ago

      when we bought our house the lilacs must have been new but over the years they have grown huge. They have taken over the alley. The path in our yard and other plants. My husband is afraid to prune them in case they don't bloom again. He's gone for a few days so I am going to prune as much as I can. They are to tall now to do much but I want to reclaim my yard. They have just finished booming so am hoping for the best

    • profile image

      cyndi 21 months ago

      My mother loved me picking them and bringing them to her for the inside of the house. Thanks for the tips on pruning. I have a big purple one in the front yard and it does not bloom to well and I would like to spread them all over the yard as well. Thank you for the tips again.

    • Lady Lorelei profile image

      Lorelei Cohen 4 years ago from Canada

      Ah it is springtime again and the lilacs are just opening their blooms where I live. They are such a fragrant flower I can see why they are so very popular as a choice of wedding flower. Hope you are having a wonderful spring.

    • vineliner57 profile image

      Hal Gall 4 years ago from Bloomington, IN

      I can smell the lilacs now. I can't wait for spring!

    • GardenIdeasHub LM profile image

      GardenIdeasHub LM 5 years ago

      I love lilacs. Thanks for the tips!

    • favored profile image

      Fay Favored 5 years ago from USA

      Yes, I've never seen a yellow lilac.

    • Lady Lorelei profile image

      Lorelei Cohen 5 years ago from Canada

      I didn't realize that there were so many shades of lilac. I am used to just seeing the light purple and the white variety. Lilacs sure are a fragrant flower. I love their scent.

    • LiteraryMind profile image

      Ellen Gregory 5 years ago from Connecticut, USA

      The smell of lilac is uplifting and mood changing. Nothing beats it. Never knew you had to prune lilacs -- good to know.

    • squidoopets profile image

      Darcie French 5 years ago from Abbotsford, BC

      I always used to bring my mom lilacs from the neighbour's yard for mother's day and her birthday, which is in May as well. They're still her favorite flowers :)

    • profile image

      TheDeeperWell 5 years ago

      I have native ceonothus, a white California lilac that blooms at the edges of my back yard meadows. It is my favorite scent of spring.

    • Steph Tietjen profile image

      Stephanie Tietjen 5 years ago from Albuquerque, New Mexico

      My Lilacs (lavender and white) are blooming right now! I appreciate the info on pruning.

    • Diana Wenzel profile image

      Renaissance Woman 5 years ago from Colorado

      Really appreciated learning how to care for my lilacs. I have a lilac bush in front of my house but it has not yet bloomed. I stopped by to learn about fertilizing it. The pruning is bonus information. Lilacs remind me of childhood and enjoying the lilacs that were blooming around nearly every farmhouse. My property would not seem complete with lilacs.

    • profile image

      anonymous 5 years ago

      I think that I could even smell the lilacs here! I sure wasn't aware that there were so many varieties and certainly didn't know anything about caring for them. I love the story about you having descendants from your grandfather's beautiful white lilacs...blessed!

    • ecogranny profile image

      Kathryn Grace 5 years ago from San Francisco

      Lilacs always rank right up there as one of my two or three favorite flowers of all time. Only the sweet-smelling English violet consistently beats it for first place. Beautifully done page. If ever I get to live with a garden again, I will have lilacs.

    • profile image

      anonymous 5 years ago

      There is nothing in the garden as beautiful as a lilac.

    • flycatcherrr profile image

      flycatcherrr 5 years ago

      I really like lilacs (and so do my bees) and though I have never got around to deadheading them, they do bloom like billy-ho! I can only grow the vulgaris here, though, and perhaps they aren't as particular as the lovely hybrids that are beyond my microclimate's reach... Lovely and helpful lens, Anthony, as always!