It’s crucial to know when to prune lilac bushes. Most lilacs don’t need to be pruned until they are between 6 and 8 feet (2 and 2.5 meters) tall. Lilac plants should be pruned as soon as the flowering is finished. This gives new shoots plenty of time to grow before the upcoming blooming season. Lilacs can lose young, budding buds if they are pruned too late.
Early spring is the ideal time to prune lilac bushes or shrubs completely to a few inches above the ground. As long as there are still a few healthy shoots present, new shoots will continue to grow throughout the normal growing season. Remove any ugly shoots when the growing season is finished.
Lilac bushes’ health and bloom output depend on regular pruning. Lilacs are typically quite hardy, and with the right pruning, they will grow back bigger and better than before.
When should lilac bushes be pruned?
All lilacs should generally be clipped right away in the spring after they have finished blooming. Lilacs set their flower buds for the following year immediately after the current year’s flowers have faded, therefore trimming later in the summer or fall will result in the removal of most or all of the blossoms for the following year. The larger common lilacs as well as the shorter or more “shrub like” cultivars are all subject to this timing guideline. While the “when” of lilac trimming is rather simple, the “how” is a little more difficult. For the time being, we’ll refer to lilac pruning as either maintenance pruning or rejuvenation pruning to keep things simple.
For the winter, do you trim back lilac bushes?
An old, overgrown lilac was one of the few plants that endured my garden restoration. The fact that it obscured my neighbor’s garage and, more importantly, sported steel-blue double flowers, led me to rescue it. Although the blossoms on this shrub were both lovely and fragrant, it was difficult to appreciate them because there were so few of them. I decided to go with a rejuvenation pruning because I knew there was no reason to give up on this long-neglected plant because lilacs can handle severe pruning.
On stems that are no older than five or six years, the common French lilacs (Syringa vulgaris cvs.) yield the most and the largest flowers. The flowers get fewer, smaller, and farther away as the stems get older. A lilac, however, may reliably produce blossoms for decades with the right trimming. The method you choose will depend on how old your shrub is. Plants are maintained annually to keep them healthy. A more drastic trimming may be necessary for lilacs like mine that have seen better days.
Lilacs should be clipped annually to encourage healthy stem development and strong growth that improves flowering. Cutting sick, deformed, and unproductive stems to the ground constitutes annual pruning. I thin and cut back some stems as well to promote healthy, evenly spaced growth. To prevent them from growing too far away from the center of the plant, I also pruned a few of the new shoots that emerged from the roots. I left a few inches between each stem to prevent crowding. Since they produce the most, I maintain the pencil-thick shoots that extend all the way to the ends of the branches. Small, twitchy growth is unproductive and won’t blossom. This growth can indicate an excess of aged, unproductive stems or too much shadow. Remove stems as soon as possible after blossoming, or in late winter if you don’t mind losing a few blooms. Cut off stems and shoots at or just below the soil line.
Dwarf lilacs rarely need pruning
Both the “Palibin” Meyer lilac (Syringa meyeri “Palibin”) and the “Miss Kim” Manchurian lilac (Syringa pubescens ssp. patula “Miss Kim”) are twiggy-habiting, somewhat small lilacs. On these types, just deadheading is needed in terms of pruning. You can prune some of the older stems as the plants get older to make place for younger, more robust stems. In contrast to regular lilacs, these plants hardly ever spread out of control. They might never need to be entirely regenerated if you only undertake a tiny amount of trimming every few years.
After the blooms have faded, deadheading, another aspect of annual maintenance, should be carried out as soon as feasible. Just above the two new shoots that slant out from the stem that stopped with the old bloom, the base of the old flower cluster should be cut off. The new shoots will develop throughout the course of the summer, produce flower buds, and culminate in a cluster of flowers the following spring. While not as crucial as the annual thinning, eliminating the old blossoms enables the plant to focus more of its energy on developing robust branches and flower buds. In June, I deadhead and thin my plants as needed.
While performing this yearly maintenance, I occasionally come upon a young, robust shoot that may be getting too tall but is still a good, productive stem and is a candidate for tipping off. I cut the wasted flower’s entire top stem back to one or two side shoots at the desired height rather of just cutting it off at the base. The side shoots that are now near the top of the bush are encouraged to grow vigorously and develop flower buds for the following year by this cut, which also aids in shrinking the shrub.
My own old, overgrown lilacs need more severe pruning. I went outside in the early spring before growth got going to get a good look at the bush. I looked to see if the plant had been grafted before I began chopping. I immediately cut it down to the ground as it hadn’t (for a grafted plant, see the panel below). I recognized that this drastic trimming would result in the plant losing part of its aesthetic appeal for a few years because lilacs bloom on the growth from the previous season. However, I was also aware that the reward—more blossoms and a stronger plant—would be worthwhile.
It’s crucial to nourish the plant after rejuvenation pruning with compost, composted manure, or a balanced chemical fertilizer and to make sure the soil pH is close to neutral, which lilacs appreciate. In the upcoming years, these supplements and some high-quality mulch will help to encourage vigorous new growth and enhanced flowering.
Has your lilac been grafted?
If your lilac has been grafted, check it out before you start making cuts to the stems. Grafting is a method of plant multiplication in which the scion, or branch, of one species is joined to the rootstock, or stem, of another species. This is typically done to enhance a plant’s look or traits. A graft union, where the cultivar’s scion wood joins the rootstock several inches above ground level, should be obvious. An apparent change in the bark from the rootstock to the scion’s bark, as well as a little swelling at the graft union, are things to watch for. If your plant has been grafted, all of your cuttings must be made above the graft union, and you must prevent shoots from the rootstock from developing into new flowering stems. Flowers of the desired shape or color will not be produced by shoots that emerge from the rootstock.
How much should lilac bushes be pruned?
Never remove more than one-third of a shrub’s stems in a single pruning season for lilacs. I just cut the branches of the lilac tree down to a manageable height when they started to stray too close to the eaves. After trimming the dead blossoms, I decided to call it a day. A little minor thinning might also be done to promote new growth.
In late winter or early spring, a more vigorous pruning should be performed, perhaps on older shrubs that haven’t been routinely tended to. At this time, you should remove any old wood and damaged stems while keeping the more recent growth. Reduce the aging stems to the ground.
I’ll simply cut any very long sections off the Bloomerang lilac to keep the shrub’s form. Because bloomerangs naturally have a spherical habit, you don’t need to bother about sculpting the bush too much. My plant has been in the garden for a while and is still adorable and manageable.
Is it possible to trim down an overgrown lilac bush?
We have two large, mature lilac plants. They no longer flower frequently and don’t appear to be healthy.
Your lilac sounds like it needs treatment, to be honest. Major restorative pruning should be spread out over three years to avoid stressing your lilacs.
Cut back roughly a third of the largest branching trunks to the ground once the spring blooms have finished. Then, cover it with fertile material such as compost or grass clippings (but only if they are free of herbicide residue). During the growing season, new branches should emerge from the earth.
An ideal pH for lilacs is around 7. Since the soil in Western Oregon is frequently too acidic for lilacs, I add extra lime every year.
Should lilacs be deadheaded?
The removal of spent flowers to encourage new blooming—deadheading—is a crucial part of lilac maintenance. Lilacs should be deadheaded as soon as the flowering is finished to allow the plants to grow robust, healthy buds that will flower vivaciously the following year. According to the University of Minnesota Extension, you can use a hand pruner, but larger plants could require a hedge trimmer. Only the dead blossom should be removed; the plant should still have two leaves.
According to the Chicago Botanic Garden, you should prune lilacs at the same time as you deadhead them since they set the blossoms for the following year quickly after flowering. By doing this, you can prevent damaging or removing the developing buds. Three to four years after planting, you should start pruning lilacs. It might be necessary to trim back overgrown lilacs to just a few inches above the ground. Winter is the ideal time to complete this. In this instance, it will take the shrub one or two growing seasons to start blooming once more.
What distinguishes a lilac bush from a lilac tree?
Lilac bushes (also known as shrubs) are characterized by their numerous woody stems that emerge from the plant’s base. In contrast, the trunk of the majority of lilac trees is the only woody stem. However, your neighborhood garden center might also sell shrub lilacs that have been grafted onto a single stem to give them the appearance of miniature trees.
The choice between a lilac tree and a lilac bush is typically determined by the amount of space available. Lilac bushes come in a range of sizes and can be placed in more compact areas of a garden. A lilac tree requires space to reach heights of 20 feet and widths of 15 feet. Both require sunlight to bloom well.
Does new or old wood produce lilac blooms?
What specifically prevents these traditional plants from blooming? Instead of focusing on just one theory, consider a number of potential causes for this issue, including (in addition to illnesses and pests):
- Pruning when it’s not necessary
- The flower buds die in the cold
- placing your lilacs in the incorrect location
- The shrub in question either isn’t old enough to generate flower buds or is too old to do so.
You’ll see that while reasons one and three point to the gardener having done something incorrect, arguments two and four point to no one having done anything incorrect.
Why does it matter what time of day you prune? Shrubs called lilacs produce flowers on rotting wood. This indicates that the flower buds for the upcoming spring’s blooming season have already been formed on the growth from the previous year. When this growth is pruned, the flower buds and, consequently, the blooms they would have produced, are lost. Because of this, it is recommended that you clip lilac bushes as soon as they finish flowering (before they have set bud for next year).
Click Play to Learn How to Prune Lilacs
Despite being a relatively cold-hardy plant, the common lilac (Syringa vulgaris) can suffer harm if a hard frost or freeze occurs just as the flower buds are about to open. As a result, that year’s flowers are lost. You can’t really stop it, so simply accept the loss and look forward to the blossoming twice as much the next year.
Where you put your lilac shrub matters a lot, just like it does with most other plants. Lilacs require full sunlight and prefer well-drained soil. If you made a mistake when you first put your plants on either of these fronts, you can be paying for it today by your lilac not blooming. However, there is a simple solution to the issue: move your shrub to a more favorable location.
Regarding the fourth reason, be aware that although though these bushes have a long lifespan, they do tend to produce fewer flowers as time passes. Implementing a rejuvenation pruning on your lilacs will solve this issue (do not expect immediate results, though). Sometimes, though, the converse is true: your plant may be too young to bloom. Allow some time.
Can lilacs be pruned to preserve a small size?
One of the joys of spring is the luscious aroma of lilacs. The lilac bush, which blooms in late April or early May with clusters of tiny purple flowers resembling bunches of grapes, is a common sight in most communities.
These are primarily common lilac shrubs (Syringa vulgaris). Kris Bachtell, vice president of collections at the Morton Arboretum in Lisle, described it as “grandma’s lilac.” It is widely known.
He said that there are hundreds of cultivated types. Although there are cultivars with magenta, pink, and white blooms as well, the majority bloom in hues of purple. They are all resilient and enduring.
Despite being widely cultivated, common lilac is difficult for some gardeners to grow. Even if some newer types are more resistant to powdery mildew, older ones are frequently deformed by it in the late summer.
The plants, which are native to rocky Balkan hillside soil, require full light and well-drained soil. An older lilac’s blooming cycle may end if nearby trees have grown to shade it.
Lilacs require frequent renewal trimming to reduce their size and thin them out. According to Bachtell, this necessitates the yearly removal of certain elder stems as well as dead wood. Lilacs also frequently sprout suckers from their root systems, which may need to be cut back.
The common lilac can simply be too much of a shrub for smaller yards because it is a large shrub or small tree that grows 8 to 20 feet tall and almost as wide.
Fortunately, Bachtell says, there are alternatives. “He said that several other lilac species are somewhat smaller. “They might be more disease- and shade-tolerant than grandma’s.
Meyer lilacs (Syringa meyeri) can reach heights and widths of 6 to 8 feet. Even though it thrives in direct sunlight, it can tolerate some shade. The flower clusters are smaller but very fragrant, and they emerge a little later than those of the common lilac. Autumn causes the leaves to become yellow. Although there are various cultivars, Palibin is the most popular.
One cultivar, Miss Kim, of the Manchurian lilac (Syringa patula), is primarily recognized. On a plant that is 5 to 8 feet tall, it bears delightfully scented light purple blossoms that turn light pink as they age. In the fall, the ruffled leaves become purple-red. Compared to other garden lilacs, the plant is a little more resistant to powdery mildew.
Hybrid lilacs that rebloom in the late summer or early fall do so less profusely than they do in the spring. Bloomerang Purple (Syringa ‘Penda’), Bloomerang Dark Purple (Syringa x ‘SMSJBP7’), and Bloomerang Dwarf Pink (Syringa x ‘SMNJRPI’) are just a few cultivars in the Bloomerang line. They are all smaller than typical lilacs, although cultivar differences in size should be noted on the label.
According to Bachtell, pruning should be done in the first week or two after the spring shrub has stopped flowering if it’s necessary to keep a lilac untangled and at the right size. Pruning in the winter will destroy buds that might otherwise develop fragrant blooms since lilacs bloom from buds that were formed the previous year.