Lilacs (Syringa) are bushes that, depending on the species, can reach heights of 15 feet and bear clusters of fragrant flowers. The flowers are attractive to butterflies and bloom in the middle to late spring. Lilacs thrive in soil that measures a pH of 6.0 to 7.0, which is regarded as neutral to slightly alkaline. This range is where the soil is least acidic and most alkaline. Only when the pH is below this range do they require lime.
Does garden lime like lilacs?
Everyone adores the lovely, fragrant lilac and how nice it is to have it in your garden to usher in spring. Everyone remembers visiting their grandparents’ home, where granny had a lilac, because they are so filled with nostalgia.
Making ensuring that lilacs are planted in the proper location is crucial when doing so. Lilacs require at least six hours in direct sunlight. They prefer to be the center of attention in their own space, so avoid planting them next to trees that already exist in the area because they don’t appreciate shade or root competition.
Create a foundation planting for them at the end of your landscaping, next to your house, or plant lilac hedgerow borders along the perimeter of your property. Put them in the middle of your backyard as a stand-alone plant. Just don’t cram them into an already-established space.
Lilacs require neutral, well-drained soil. They dislike conditions that are damp, muddy, poorly drained, and have acidic soil. You should feed lilacs with garden lime to balance out the more acidic soil conditions that are prevalent in Connecticut.
We sell pH test kits if you’re unsure if your soil is neutral or acidic, or you can have your soil tested at the Connecticut Agricultural Experiment Station in New Haven.
Pruning is a crucial part of lilac maintenance. A lilac can start to exhibit indications of neglect after a few years if basic maintenance is neglected, such as suckers that need to be pulled up from the ground. A lilac will grow to a height of six inches when it is healthy, and its shoots will be pencil-thick in width. Thin and spindly growth is an indication that the plant is unhealthy and requires fertilization.
Every year, prune 1/4 to 1/3 of the oldest branches and remove small branches and unhealthy canes to encourage the plant to produce lots of flower buds. Keep the plant’s main stem sturdy to allow for good airflow around the base.
If you’re going to sheer it, wait until after the flowers have bloomed. You won’t get any flowers this season if you go outside today and chop a third of it down. Before the Fourth of July, don’t forget to deadhead the plant after it blooms and as soon as the blossoms start to turn brown. You run the danger of affecting the blossoming for the following year if you wait too long.
Finally, water the base of the plant every time because lilacs dislike heavy overhead irrigation.
Even young lilac plants produce blossoms, which enhance the beauty and aroma of your yard. You can brighten up your yard with happy, healthy plants if you take good care of them.
Which fertilizer is ideal for lilacs?
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.
How can I improve the bloom of my lilacs?
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.
Are lilacs amenable to acid?
Lilacs prefer soil with a pH between 6.5 and 7.0, which ranges from slightly acidic to slightly alkaline. If the pH is either too high or too low, the bushes may suffer because the nutrients they require from the soil may not be easily available.
How can you promote the growth of lilacs?
3. Take the plant out of its pot and place it in the hole. Make sure the top of the root ball is about an inch or more above the soil surface.
4. Apply the soil mixture all the way around the root ball, pressing it down firmly.
5. Take a long drink.
6. Mulch the area you just planted to a depth of 2 inches, being careful not to pile mulch up against the base of the plant. This will help keep the soil moist and prevent weeds from sprouting by denying them access to sunlight.
How to Water Lilacs
After planting, monitor your plants frequently, and water them once or twice a week, or anytime the top inch of soil becomes dry. While watering, count to 10 to make sure you’re providing each lilac plant with enough moisture. (If the plant becomes too dry, the leaves will start to droop.) You can reduce watering to every other week once plants have been planted and have had a few months to establish themselves. Lilacs won’t require additional water during the second growing season or later unless there hasn’t been rain in your location for a month or more.
How to Feed Lilacs
Lilacs should be fed Miracle-Gro Shake ‘n Feed Flowering Trees & Shrubs Plant Food after they have bloomed in the spring to encourage the development of robust roots. This plant food is jam-packed with nutrients for your plants, including kelp, earthworm castings, feather meal, and bone meal. These ingredients nourish soil bacteria, which in turn break down organic matter into nutrients for your plants.
How to Help Prevent Disease Problems with Lilacs
Powdery mildew is the main problem with lilacs, especially common lilacs. What’s the best approach to prevent this? Purchase and plant lilac cultivars that resist powdery mildew (check the plant tag or online description). Lilacs benefit from being planted in areas with good airflow. This fungus disease won’t respond to spraying, and it will finally go away on its own.
How to Deadhead Lilacs
Be sure to deadhead young lilacs as they start to bloom (this could take a few years!). Deadheading involves clipping off faded flowers at the base as soon as they start to droop and fade. In response, the plant will use more energy developing new flower buds for the upcoming spring.
How to Prune Lilacs
Although the newer, smaller lilac kinds require less trimming than the enormous conventional lilacs, all lilacs will grow more effectively and bear more flowers with regular pruning. Here are a few possibilities:
- Cut an older lilac shrub to 8 inches above the ground in late winter (March or April), then let it grow out if it isn’t flowering despite receiving plenty of sunlight. The following March, choose 8 to 10 of the best-looking stems, and reduce them by half. Trim the remainder to the ground. The following year, new blossoms should appear.
- Selectively prune 1/3 of the branches all the way back to the ground each year to revive shrubs that aren’t flowering well instead of chopping the shrub all the way down.
- Cut back branches to reduce size as soon as the shrub’s flowering has finished.
How are lilac Fullers made?
Cutting off the tops of stems that have grown out of control is frequently insufficient when pruning lilacs. It is typically preferable to remove the entire stem. The best way to trim lilacs is with clippers. To avoid spreading and promote later blooms, remove spent blossoms right down to the stems. Three-quarters of the branches should be pruned. Remove any shoots that are emerging from the main trunk and are growing close to the ground. Lilacs within the inner branches may need to be trimmed in order to increase air flow or let more light through.
However, it may be essential to prune the entire bush or tree to approximately 6 or 8 inches (15-20 cm) above the ground if lilac shrubs are already too big or starting to look unpleasant. Remember that it takes around three years for flowers to grow after the entire bush has been removed, so you might have to wait.
How are lilacs kept in good health?
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.