When to cut lilac flowers
Russell Tree Experts — When and How to Prune Lilacs
Please note: This article was originally published on 4/6/2020 and was republished on 6/9/2021.
Common lilacs (Syringa vulgaris) are a favorite landscape shrub here in Ohio and beyond, with flowers that provide beauty and an unmistakable fragrance every spring. Other cultivars of lilacs offer different habits and uses in the landscape, but provide the same display of flowers that we all love. In order to ensure you get the most flowers on your lilac year after year, it’s important to know when and how to prune them.
When To Prune
As a general rule for all lilacs, they should be pruned immediately after they’re done flowering in the spring. Since lilacs set next year’s flower buds right after the current year’s flowers have faded, pruning later in the summer or fall will result in cutting off many or all of next year’s flowers. This rule of timing applies to the larger common lilacs as well as the cultivars that are shorter or more “shrub” like. While the “when” of pruning lilacs is fairly straightforward, the “how” gets a little trickier. To keep things simple for now, we’ll think of lilac pruning as either maintenance pruning or rejuvenation pruning.
How To: Maintenance Pruning
For any lilac shrubs that have not outgrown their space or are still producing vibrant flowers each year, regular pruning can simply consist of any shaping that you choose to do along with removal of dead, diseased, or broken stems. You can also remove spent flowers from your lilacs to help encourage a cleaner growth habit and appearance. It’s always better to do this type of pruning by hand, rather than shearing. When making cuts, try to cut back to an outward facing bud. A good pair of hand pruners is the perfect tool for this and makes for much better pruning cuts than hedge shears.
How To: Rejuvenation Pruning
If you’ve ever had an older common lilac in your landscape that went unpruned for many years, you’re probably familiar with their overgrown, unruly habit when left alone.
Many people mistakenly believe that these shrubs have stopped flowering at this point. Oftentimes what’s actually happening is the flowers are being produced on just the upper portions of the shrub where the plant has reached a taller height and is exposed to sunlight. Once they’ve reached this stage, we’re often left to stare at bare, woody branches at eye level and below. For these overgrown shrubs, we can remove entire older canes or stems that are 2” in diameter or larger to encourage a rejuvenation of the shrub. We want to apply the rule of thirds when doing this type of pruning - Remove approximately one third of the older canes or stems each year for 3 years. This gives the shrub a chance to slowly transition back to a fuller, shorter shrub with more new growth filling in from the bottom. If you decide to drastically prune the entire shrub this way all at once rather than just a third of it, a little extra care like fertilization and watering will be important to encourage new growth.
Note that this “all at once” approach is generally not recommended for the health of the shrub.
Your lilac flowers can be influenced by many things, including the temperature, soil conditions, even disease and insect problems, but proper pruning goes a long way to ensuring they put on a great show every spring. And remember, if you have specific questions about pruning or anything tree and shrub related, your dedicated Russell Tree Experts arborist is only an email or phone call away.
*New* Video!
To accompany the above article, Walter Reins demos how to prune lilac trees in this new video! Click below!
Tips for pruning lilacs to encourage blooms for next year
A few years ago, when I went to grab the hose, I noticed a ton of branches had been torn off my lilac bush. I accused my poor husband of getting overzealous with the pruners. However, I soon discovered that the hack job was the work of a mother squirrel that was meticulously building her nest.
She’d rip off a branch or two and then run to my chimney (that’s a whole other story). I was worried about the lilac coming back the following spring, but it has been flourishing. Lilac is among my favourite spring scents—when I work outside on my deck, I take deep breaths when they’re in bloom, as they sway in the breeze. When those fragrant blooms fade, it’s a good time for pruning lilacs. So I thought I’d share a few tips!
The perfect time to prune a lilac bush is after the flowers have bloomed and faded. Spring-blooming shrubs should be pruned right after they have bloomed. If you save the task for later in the season, you risk pruning off next year’s blooms (because next year’s flower buds form on the current year’s wood)—a mistake I made in the past with an unruly forsythia!
Tips for pruning lilacs
There are three maintenance tasks I need to cross off my lilac to-do list in the spring. I need to trim the dead blooms off, prune the shrubs, and cut out suckers that have popped up underneath.
Most of the stems I’m dealing with are thin enough that I can use my hand pruners, but if stems are thicker, you may want to use a pair of bypass loppers. Make sure the blades are clean before you cut. And while the plant is blooming, use the same sharp pruners to snip bouquets. You don’t want to tear or snap off blooms, as this could harm the lilac bush.
Trimming off lilac flowers
Removing the dead flowers from your lilac bush will encourage more blooms the following year. The important thing when trimming off your flowers is that you simply cut off the spent flowers—don’t worry about any surrounding stems. If you can see next year’s blooms forming (two new shoots coming from the stem), simply focus on the spent bloom’s stem. You don’t want to cut off next year’s flowers!
To deadhead lilacs, simply snip the dead flower, leaving the stem and leaves in place. If you see next year’s growth, leave it be.Now with my dwarf Bloomerang, I want to encourage a second blooming, which should take place towards the end of the summer or early fall.
Pruning off the spent spring blooms will encourage more new growth and more blooms for that second bloom time. I could also add a light dose of fertilizer that’s been formulated for woody plants, which will also encourage the shrub to bloom again.
Pruning lilac shrubs
A good rule of thumb when pruning lilacs is not to prune more than one third of a shrub’s stems per year. When one of my lilacs climbed a little too high towards the eavestrough, I simply trimmed those branches to a reasonable height. I then trimmed the spent blooms and called it a day. You can also do a bit of light thinning to encourage new growth.
A more aggressive pruning, perhaps on older shrubs that haven’t been regularly maintained, should be done in late winter or early spring. At this point, you want to cut out older wood and malformed stems, and keep the newer stems to encourage new growth.
Cut the older stems down to the ground.
With the Bloomerang lilac, I’ll just trim any especially long pieces to maintain the shape of the shrub. Bloomerangs have a nice rounded habit in the first place, so you don’t have to worry about shaping the bush too much. Mine has been in the garden for a few years and it’s still nice and small and compact.
Removing lilac suckers
Another part of pruning lilacs is removing the suckers. What are suckers? Around my lilac there are a few new lilac trees—single stems a few feet away, shooting up from the soil, making their presence known. These are the suckers. I simply cut them off at the soil line (or slightly below). However stems close to the trunk of the bush itself, you may want to leave, as a healthy lilac has a mix of old and new stems. You could also dig up the suckers and replant them elsewhere. Who doesn’t love new plants?
Suckers that aren’t close to the actual lilac are simply trimmed at the soil line.In a pruning mood? Here’s another piece I wrote about how to prune a rose of Sharon.
This video offers a synopsis of these lilac-pruning tips.
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Lilac pruning. Basic Rules and Tips
Photo Flickr.comTips, Care Views: 60 517 0
Lilac belongs to shrubs for which correct and timely pruning is extremely important. She cannot be neglected.
This article is a continuation of material "Rules for planting and caring for lilacs" .
Sanitary and shaping trim
Sanitary pruning is best done in early spring (March - early April) and in summer immediately after flowering. However, if it was not possible to hold it in the spring, then one summer one will be enough.
In the spring, you need to remove all broken, damaged, frostbite (may form even in winter-hardy varieties, if there were strong temperature changes) branches during the winter.
It is also necessary to cut off the shoots that have grown under wet snow in early spring.
Last year's growth is also removed if it is not necessary for propagation by layering: a large number of growth takes moisture and nutrition from the main plant, and also increases the size of the bush and worsens its appearance. nine0003
In spring we do not recommend trimming lilacs in height and doing formative pruning: there is a risk of removing flower buds located on the top of the shoots.
Formation pruning, as a rule, is combined with summer sanitary and carried out after flowering. The measure includes:
- removal of branches that thicken the crown too much, weak non-viable shoots and shoots with dried tops and bases;
- cutting off shoots affected by pests and thinning the crown; nine0029
- removal of old branches, crossing shoots, small branches growing inside the crown;
- trimming the tops of the branches to form a beautiful and even crown.
Do not forget about the newly appeared growth, which also needs to be cut out.
[stextbox id="info" caption="Advice" ccolor="000000" bgcolor="F4B0FF" cbgcolor="F4B0FF" bgcolorto="F4B0FF" cbgcolorto="F4B0FF"]After sawing off large branches, cover the cut with garden pitch. So you prevent the defeat of plants by infectious diseases.[/stextbox] nine0003
Rejuvenating pruning
This type of pruning is relevant for aging native-rooted lilac bushes, both varietal and specific. If there are already few shoots on the old branch, then cut it down to the ground. Within 2-3 years, replacement shoots will form from the young shoots.
We do not recommend replacing all the old skeletal branches at once. It is better to do this gradually, 1-2 branches per year. Thanks to this, the plant will rejuvenate without losing its decorative effect.
On grafted lilacs, rejuvenating pruning is carried out up to the trunk above the grafting site.
An insulating material, such as garden pitch, is applied to the cut site.
Pruning to regulate flowering
Lilacs have a peculiarity - if one year it bloomed too abundantly, then the next year the flowering will be very weak.
For this reason, regular pruning is necessary to ensure even annual flowering of the bush. It is carried out in early spring, before the start of the growing season. At the same time, part of the shoots with an excess number of flower buds is removed. nine0003
Common lilac ‘Beauty of Moscow’
Pruning of faded inflorescences
This type of pruning is needed for laying next year’s flower buds on lilacs.
If faded panicles are not removed in a timely manner, then the nutrients of the plant will be used for fruit ripening, and the number of new flower buds will decrease significantly.
Never break or pluck out faded panicles. They only need to be trimmed, leaving small stumps.
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Cutting for bouquets
Cutting flowering branches also activates the emergence of new flower buds. However, they should not be abused - we advise you to leave about half of the inflorescences on the bush.
By cutting everything, you give the plant a signal to form a large number of new shoots, which will begin to grow everywhere, break the shape of the crown, and also deplete the plant.
Do not break flowering branches: lacerations can lead to plant disease. nine0008
Use a sharp garden tool to cut into bouquets. Pruning should be sufficiently long shoots up to two-year-old wood, while leaving no stumps.
It must be understood that when pruning lilacs, we are primarily pursuing the goal of obtaining abundant and strong flowering. Getting enough light, moisture and air, in the crown of a properly formed lilac, each skeletal branch has its own segment for development. Ultimately, pruning forms such a crown through which, as gardeners say, a sparrow can fly in winter without hitting branches with its wings.
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Lilac has faded, what to do next? Is it possible to break off lilac branches and is it necessary to cut lilac inflorescences?
Is there any point in trimming lilacs if everything is in order with them anyway? We figure out how to save a lilac bush and guarantee lush flowering for the next year.
Anna Zalesskaya
How to make a rejuvenating pruning of lilacs after flowering, how to properly care for lilacs and achieve lush inflorescences? Why is it impossible to cut off all lilac brushes with branches and how to properly deal with the growth of lilacs? Read our article. nine0003
Contents of article
Should lilacs be trimmed and why?
Many summer residents believe that it is not necessary to trim the lilac, the shrub is unpretentious and feels great without any attention. But experienced gardeners assure that pruning a bush is a very important (if not the main) step in caring for lilacs.
It is necessary to prune lilacs annually so that in the future the shrub continues to bloom magnificently, and the inflorescences do not become small.
The fact is that pruning stimulates the formation of new shoots, on which flower buds are laid for the next year. You should not delay pruning already faded inflorescences, otherwise they will begin to set seeds and spend energy on their formation, taking nutrients from the shrub. The more nutrition is spent on laying seeds, the worse the quality of new panicles will be in the future. nine0003
How to prune lilac panicles?
Cut to the nearest branch, being careful not to leave the stem between the slingshot. Then flower buds will be laid on the regrown side branches for the next year.
Under no circumstances should the flower panicles be trimmed along with part of the branch, unless you want to thin out the bush and remove interfering branches.
The fact is that lilac flower buds are formed only in the axils of the largest, upper leaves at the ends of the shoots that grew last year. If you cut panicles with part of the branches, you will remove the rudiments of these buds, and next spring you will be left without lilac flowers. nine0003
How to form a lilac bush?
This should also be done after the lilac has faded. You can cut branches that grow inside the bush or strongly deviate to the sides. You can also lower the height of the bush, but in this case there will be much fewer flowers next year.
If a lilac bush has a lot of young shoots, then everything that interferes can also be cut off. It is enough to leave 4 main trunks so that the rest of the growth does not take strength from the bush. Shoots and extra stems are cut at ground level or slightly lower, leaving no stumps. nine0003
If the lilac bush is already more than 6-7 years old and has strongly developed in height, it will be difficult to reach the inflorescences, and it will be difficult to cut them, which means that over time the flowers will become smaller and thinner. To prevent this from happening, it is better to immediately carry out anti-aging pruning and thinning of the shrub. If a healthy strong shoot is too high, it can be shortened to a pair of side shoots at the desired height for you. Lilacs will quickly grow new shoots, but they will bloom only after a year.
Is it true that lilac branches are better to break off?
There is a common belief that lilac should be broken, not cut, and the more you break, the better the bush will bloom later.
The truth is that you should never do this. In park gardens, rare varieties of lilacs are constantly destroyed in this way.
Each pruning is stressful for the plant, so it is important to use a quality sharp pruner. A neat, even cut of a pruner will quickly overgrow, and broken, split branches (like torn wounds) will overgrow for a very long time and become a source of the spread of various infections. nine0003
How to choose a place for a lilac bush
Lilac should not be planted in a damp and dark place, because the shrub, although unpretentious, still prefers light soils and sunny places and does not tolerate stagnant moisture in the roots.
