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You can prune a reblooming lilac to keep it blooming beautifully all season long.
Pruning a reblooming lilac isn’t complicated, but it does require a slightly different approach than pruning a traditional lilac.
If you’ve been wondering how to prune a reblooming lilac without sacrificing those second and third flushes of flowers, you’re in the right place.
In this post, we’ll walk through exactly how to prune a reblooming lilac, when to make each cut, and the simple techniques that keep your shrub vigorous and full of color.
Let’s dig in.
Why Pruning a Reblooming Lilac Is Different
The biggest mistake gardeners make is treating a reblooming lilac like a traditional one.
A standard lilac blooms once in late spring, so you prune it right after that bloom fades.
But a reblooming lilac, like Bloomerang or reblooming lilac varieties, produces flowers on both old wood and new wood.
That means when you prune a reblooming lilac, you have to be strategic about which stems you remove and when you remove them.
If you cut too much at the wrong time, you’ll accidentally remove the buds that would have become your second and third rounds of flowers.
So, learning how to prune a reblooming lilac correctly is the key to enjoying those extended bloom cycles.
1. The Two-Flush Rule Matters
To know how to prune a reblooming lilac, you first need to understand that these shrubs bloom in two main waves.
The first flush appears on old wood from the previous year’s growth.
The second flush comes later in summer on new wood that grows after the first bloom.
When you prune a reblooming lilac, you need to protect the new wood if you want that second flush.
This is why heavy pruning in late summer or fall is a bad idea.
Doing so removes the new wood that would carry next spring’s first flush.
2. Light Pruning vs. Hard Pruning
There are two main ways to prune a reblooming lilac: light pruning and hard pruning.
Light pruning is what you’ll do most years to remove spent flowers and shape the shrub.
Hard pruning is a renovation technique for older, woody, overgrown lilacs that need a fresh start.
Both have their place, but you need to know exactly when to do each one.
When to Prune a Reblooming Lilac
Timing is everything when you prune a reblooming lilac.
The best time to prune a reblooming lilac is immediately after the first bloom fades in late spring or early summer.
This is your main pruning window.
At this point, you can safely remove spent flower clusters and do any shaping without harming the upcoming second bloom.
Why does this work?
Because the shrub has all summer to push out new growth, and that new growth will produce the second wave of flowers.
You can also do a very light tidy-up in midsummer after the second flush finishes, just to remove faded blooms.
But avoid pruning a reblooming lilac after mid-August.
Any cuts made that late will stimulate tender new shoots that won’t harden off before winter.
1. Deadheading After the First Bloom
The simplest way to prune a reblooming lilac is to deadhead it after that first big flush of flowers.
Grab a pair of clean, sharp pruners and cut off the spent flower clusters right where they meet the stem.
Make your cut just above a pair of healthy leaves or a leaf node.
This not only cleans up the plant but also encourages branching.
More branches mean more spots for future flower buds.
So if you’re wondering how to prune a reblooming lilac for maximum blooms, deadheading is your number one move.
2. Shaping and Thinning in Early Summer
After the first bloom, that’s also the time to do any structural shaping.
To prune a reblooming lilac for shape, remove any crossing branches, dead wood, or stems that rub against each other.
Also, take out the oldest, thickest canes at the base.
This is called renewal pruning.
By removing a few of the oldest stems each year, you encourage new, vigorous shoots from the base.
This keeps the shrub younger, healthier, and more floriferous.
Just make sure you never remove more than about one-third of the total stems in any single year.
3. Avoid Pruning in Late Summer or Fall
One of the most important things to remember about how to prune a reblooming lilac is what not to do.
Do not prune a reblooming lilac in late fall or winter.
Unlike some shrubs that benefit from winter pruning, reblooming lilacs do not.
That’s because winter cuts remove the old wood that holds next spring’s first bloom buds.
You’ll essentially cut off your spring show before it even starts.
So keep your pruners in the shed from late summer until after the first bloom.
How to Prune a Reblooming Lilac That’s Overgrown
What if your reblooming lilac has been neglected for years?
Can you still prune a reblooming lilac that’s become a tangled mess?
Absolutely.
You’ll just need to use a more aggressive approach called renovation pruning.
1. The One-Third Rule for Renovation
To prune a reblooming lilac that’s overgrown, start by removing the thickest, oldest one-third of the canes all the way down to the ground.
Use a pruning saw or loppers for these larger stems.
This opens up the center of the shrub to light and air.
It also stimulates strong new shoots from the base.
Do this in early summer after the first bloom, and the plant will reward you with fresh growth.
2. The Three-Year Method for Severe Cases
For very old, woody lilacs, you might need to spread the renovation over three years.
In year one, remove one-third of the oldest canes.
In year two, remove another third, including any weak or spindly growth.
In year three, remove the last of the old canes.
Throughout the process, you’ll prune a reblooming lilac right after the spring bloom so you never miss out on flowers.
This slow, steady approach is the gentlest way to prune a reblooming lilac and get it back to peak performance.
What About Pruning Reblooming Lilac Suckers?
Reblooming lilacs often send up suckers from the roots, and these can sap energy from the main plant.
When you prune a reblooming lilac, you should also deal with these suckers.
To prune a reblooming lilac sucker, pull it out by hand if it’s small, or cut it off below the soil line with pruners.
You can do this at any time of year, though early summer is easiest when the soil is soft.
Removing suckers keeps the plant’s energy focused on blooming rather than spreading.
So, Can You Prune a Reblooming Lilac?
Yes, you can prune a reblooming lilac, and you should do it every year for the best display.
The key is to prune a reblooming lilac right after the first wave of flowers fades in early summer.
Deadhead spent blooms, remove a few oldest canes, and shape lightly without overdoing it.
Avoid all pruning from late summer through winter to protect next spring’s buds.
So, now you know exactly how to prune a reblooming lilac for continuous color from late spring through fall.
Get out there, make those careful cuts, and enjoy a lilac that just keeps on giving.