Why Do Lilacs Not Bloom

Although there are several potential solutions to this problem, pruning might hold the key. Lilacs blossom on the growth from the previous year, so it’s crucial to cut them as soon as the spring blooming is through. Pruning a lilac in the summer, fall, or winter may result in the removal of buds that would have bloomed the following spring.

After the spring bloom, try to only lightly prune the plant. If you want to avoid delaying the next bloom by drastically pruning your lilac shrub, simply remove the oldest and heaviest branches and trim the inner branches to make room for sunshine to enter the bush.

Take into account the age of your lilac bush, which by this point may have evolved into a tree. On younger wood, lilacs bloom at their best. If the majority of your lilac’s structure is old, decayed wood, blooms may be scarce. An elder lilac can require rejuvenation pruning, followed by a two- to three-year wait before it can bloom fully again.

What stops lilacs from blooming?

A. There are a number of potential causes for your lilac’s failure to blossom. Lack of sufficient sunlight is the main culprit. Lilacs (Syringa) should be planted in an area with at least six hours of direct, bright sunlight per day. They can withstand a wide range of moisture levels as long as they are grown in soil with good drainage.

If your lilac is clipped at the wrong time of year, it might not blossom for another reason. Lilacs bloom in the spring on the growth from the previous year, and soon after, they begin to form the buds for the following year. Within a few weeks of the plant blooming, pruning must be done simultaneously with the removal of the wasted flowers in order to prevent the removal of the buds for the following year. A late freeze can harm flower buds on types that bloom early.

Lilacs have a tendency to mature into overgrown, leggy shrubs with minimal foliage at the bottom. When this occurs, it might be required to prune them to within 12 inches of the ground in order to completely rejuvenate them. When the shrubs are dormant in late winter, this should be done. Lilacs benefit from this repair, although their blooming cycle will be hampered for at least one season. Lilacs can receive a rejuvenation pruning over a two-year period to stop the interruption of bloom cycles. Half of the shrub’s stems should be hard pruned the first year, and the remaining stems the following year.

Lilacs do not consume a lot of food. Excessive fertilization, particularly nitrogen fertilizer, can frequently promote luxuriant vegetative growth at the expense of flower development. A lilac’s failure to bloom could potentially be due to its proximity to turf that receives frequent fertilization.

How can I increase the blooming of my lilacs?

Lilacs with good form require annual pruning to maintain the rounded shape that most gardeners like. For the purpose of regulating the shrub’s total height, pruning is also crucial. These robust growers can grow up to and over 20 feet tall, depending on the variety. A tall lilac’s flowers will also blossom close to the top of the plant, out of reach and possibly beyond where they can be easily seen and appreciated because the majority of the buds develop on the tips of the branches.

  • Pay close attention. This spring, as your plants blossom, pay particular attention to the shrub’s shape. Note where the plant has the most of its flowers as well. Lilacs bloom toward the tips of their branches; the sunniest spots will have the largest and most vibrant flowers.
  • Selectively prune. Selective pruning should be done after the blooms have faded and died to manage height and restore shape. Lilacs typically only need to be deadheaded and a few choice branches removed to enhance the form and look of the plant. It’s vital to only prune the limbs and branches required to maintain a properly shaped and proportionate shrub because they flower on the older stems.
  • Cut those suckers off. Each year, healthy lilacs send up new suckers from the ground. Cut back some of the suckers and get rid of any twisted or lanky branches.
  • Cut back by a third. The inside of the plant may get crowded with a tangle of older limbs over time and as it ages. Lilacs will consistently bloom for years with no maintenance, but some elderly plants may start to produce less. Cut back the chosen shoots and branches at ground level to eliminate around one-third of the plant each year in order to revitalize an older plant and promote more flowers.

Does pruning encourage or delay a lilac’s growth?

Although harsh pruning promotes new growth, because lilacs only bloom on old wood, it may take the plant several years to recover from a severe pruning before it can bloom effectively once more.

What should you do if lilacs refuse to bloom?

Lilacs often bloom quite consistently, although occasionally they don’t. To ensure that yours grows, follow these suggestions:

  • Usually, the issue is a lack of sunlight. Each day, the sun should be exposed for at least six hours.
  • Nitrogen in excess might be problematic. Lilacs are frequently cultivated in lawns, and nitrogen-rich fertilizers are utilized to make lawns greener. This results in lovely green foliage on the lilac but minimal blossom. Avoid using nitrogen-rich fertilizers.
  • Make sure to prune when the season is perfect. Remove any dead or damaged timber in the early spring. However, avoid performing any significant pruning because you can just remove the dormant flower buds. It’s acceptable to perform more significant trimming after the flowers have faded, such as reshaping or rejuvenating an elderly bush. The old flowers can be taken out as well. Just be sure you finish it before the middle of the summer. A few of the flowers from the upcoming season may be lost if you wait too late.

Visit the Lilac Planting and Care page for a comprehensive guide to lilac planting and care.

How can a lilac bush be revitalized to produce more flowers?

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.

Which month 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.

Are lilac bushes suited to coffee grounds?

Lilac plants don’t require a lot of food or fertilizer. A 10-10-10 fertilizer mixture applied yearly in the early spring is what we advise. (The amounts of nitrogen, phosphorus, and potassium, or NPK as they are popularly known, are represented by the digits 10-10-10 in the formula.) Early spring fertilization of lilacs with a high phosphorus solution encourages blossoming.

Coffee grounds and grass clippings are also excellent sources of nitrogen. Use in moderation since an excess of nitrogen in the soil can lead to subpar blooms. The ideal soil conditions for lilacs are slightly alkaline (6.5–7.0 pH), wet, and well-drained. The soil may become more alkaline by adding bone meal to it. Use Miracle-Gro Shake ‘n Feed Flowering Trees & Shrubs Plant Food in the spring if you decide to feed your plant. Last but not least, lilac plants dislike acidic soil. Epsom salts can be used to encourage blossoming while the plant is dormant.

Can you trim back lilacs to the ground?

The lilac tree will resemble nothing more than a twig in the garden by the end of September. It shouldn’t be reduced to the ground, though. Despite the fact that lilac trees are known for their resilience, it will likely take several years before you see blossoms again because you cut off all the blossoming growth.

If your lilac tree is more mature and unruly, it may require more aggressive pruning and some chopping back; just make sure that it doesn’t take up more than a third of the tree.

How can I fix my lilac bush?

Examine the branches for damage like as exit holes and sawdust, sap, and frass, which are indicators of insect infestation. Damage from damaged branches could be stopped by pruning them off. Next spring, as the lilacs begin to bloom, keep an eye out for the adults and place pheromone-activated traps (see Lilac borer).

Which fertilizer is ideal for lilacs?

Lilac bushes respond well to fertilizer made from bone meal. This is as a result of increased soil alkalinity. It is a simple natural plant food that the lilac may consume.

Lilac fertilization isn’t necessarily required until the first and second years after planting. To sweeten the soil and prevent too much acidity, they could be fertilized with superphosphate and limestone when they are planted.

You can exclude standard fertilizer mixtures if the soil has the right balance and has a lot of organic matter. The only bushes that will truly benefit from annual feeding are those planted in poor soil. When you do feed the plants, use a 5-10-10 ratio. Around the plant’s root zone, distribute 1 cup (237 ml) of granular food evenly, and then water the soil.