Lilacs are renowned for their longevity and hardiness. Numerous lilac shrubs reach ages of greater than 100. They frequently outlive the residence of the gardener who planted them due to their extended lifespan. As a result, if you’re driving along a country road and come across a few what appear to be random lilac bushes, it was probably a farm or house a century ago.
Try growing lilacs in your garden if you haven’t already. They not only return every year, but they also put on a display for the senses with vibrant blossoms and enticing scents. Lilacs have a lot to offer, and learning about their history demonstrates just how unique these plants are.
How can an ancient lilac tree be revitalized?
The common purple lilac is a hardy, dependable shrub that can grow up to 20 feet tall. Unfortunately, the lower, shady sections of lilac shrubs typically lose their leaves as they get older. Large, overgrown specimens as a result are frequently leggy and ugly. Pruning can restore or rejuvenate old, neglected lilacs. Home gardeners have two alternative pruning techniques to pick from.
Cutting the entire plant back to within 6 to 8 inches of the ground in late winter is one method of renewing a huge, overgrown lilac (March or early April). A significant number of shoots will sprout during the growth season as a result of this aggressive pruning. Select a few sturdy, robust shoots to construct the shrub’s framework, keeping a few of them, and cut off all the others at ground level in the late winter of the next year. To promote branching, head (clip) back the retained shoots to just above a bud.
Cutting back the overgrown shrubs over a three-year period is a second method for pruning mature lilacs. In late January, start the process by digging up and removing one-third of the big, old stems. The following year, trim out half of the remaining old stems (again in late winter). Additionally, trim out some of the recent growth. Keep a few healthy stems that are evenly spaced apart and cut off the rest. In the third year’s late winter, completely remove all of the old wood. It is also necessary to thin the fresh shoots more. This pruning technique should enable you to take pleasure in blossoms every spring because lilac wood must be three years or older before it blooms.
Within a few years, with the right pruning, an old, overgrown lilac can be converted into a robust, appealing shrub. Pruning should be a frequent component of the lilacs’ management regimen after they have been revived. By cutting a few of the oldest branches every three to five years, the shrub can be kept strong and healthy.
(This article, which first published in the Sunday edition of the Lincoln Journal Star Newspaper in February 2005, has since been amended. Consult the Terms of Use for details on how to copy this content and use any images or visuals.)
When should lilac trees 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.
Fungal diseases
This season, the Lilac Pseudocercospora leaf spot, a fungus, was detected in lilac samples examined by the Plant Disease Clinic. The same symptoms have been recorded (yellowing then browning leaves, dieback).
The PDC places a strong emphasis on sanitation because it appears that Pseudocercospora spores can survive on plant detritus for a number of years (leaves, stems, dead flowers, bark).
- To assist lessen the possibility of reinfection the next season, remove fallen leaves.
- Consistent watering and renewal cutting to reduce density will sustain the stressed plant.
Several of the plants in our landscapes, including lilacs, are afflicted by verticillium wilt. Verticillium dahliae and Verticillium albo-atrum are the two fungi that cause it. For a plant with this fungus infection, there is no cure.
- As a result of the fungi clogging the branch’s vascular system and preventing the transfer of water and nutrients, individual branches turn brown and die quickly.
- To increase plant longevity, increase watering and fertilization.
- The disease can spread across all sections of the afflicted plant, thus the best preventive is to buy resistant cultivars and practice proper hygiene.
Insects
The Lilac Borer, sometimes known as the Ash Borer, is a clearwing borer moth that creates tunnels in lilac stems.
- Frass, sap, and sawdust are warning signs (excrement).
- Some plants can withstand this harm.
- Others see branch dieback, and occasionally the entire plant dies.
- They won’t likely catch anyone’s attention.
Jeff Hahn, an extension entomologist, confirmed that no lilac borer samples have entered his lab this year.
Herbicide damage
Broadleaf weed treatments on lawns may volatilize, changing to a gas, and float onto unintended plants if sprayed during periods of extreme heat and humidity.
Herbicide damage signs like cupping and browning would appear in patterns:
- along a hedge’s one side but not the other,
- bushes positioned in or close to lawn areas, at the same level throughout their bases,
- and most critically, away from the area’s predominant winds.
Lilac hedges next to agricultural fields or other sizable herbicide-treated areas may experience damage in this manner.
Zones:
The majority of lilac types can withstand cold temperatures in zones 3 to 8, although others, like Scentara Double Blue, can (S. hyacinthiflora). There are some cultivars that don’t require a winter chill, like as “Lavender Lady” (S. vulgaris), which is heat tolerant to zone 9. The majority of others do need a wintertime period of cold and dormancy.
Height/Spread:
The common lilac, Syringa vulgaris, reaches heights of 12 to 15 feet and widths of 10 to 12 feet. The majority of dwarf types are smaller and reach maturity at 4 to 6 feet tall and 3 to 7 feet broad. Syringa reticulata, often known as the Japanese tree lilac, grows up to 30 feet tall.
Bloom Time:
The majority bloom in late May, however there are new re-blooming kinds, such the Bloomerang series, as well as early spring, mid-spring, and late-season blooming variants.
Color:
The common lilac (Syringa vulgaris) has gray to gray-brown bark, purple blooms, and dark gray-green to blue-green foliage (with no fall color change). But there are actually seven recognized hues for lilac flowers: white, violet, blue, lavender, pink, magenta, and purple, with several variations of each hue.
Other:
True lilacs, such as the California, mountain, and wild lilacs, are truly members of the genus Ceanothus. Butterfly bushes are frequently referred to as summer lilacs, especially sterile and non-invasive varieties.
If cut, will lilacs grow back?
Lilacs are a lovely addition to any landscape, but proper pruning is essential if you want your bush to maintain its beauty and continue to produce its distinctive, fragrant blossoms year after year.
“The aroma of lilacs fills the air when the mauve, pink, purple, or white blooms open. They can also be planted in containers and require a sunny location with rich, fertile soil that drains well, according to Leigh Clapp, a gardening expert for Period Living.
Lilac trees shed their leaves every fall because they are a deciduous plant. On the growth from the previous year, they develop new leaves and blossoms the next spring. A lilac, on the other hand, will continue to grow and can spread up to 9 feet wide and 21 feet high if it is not clipped.
As the ends of the branches were the parts of the tree that were actively growing the previous year, the lilac will only begin to bloom at these points. branches from earlier years that are still around are turning woody. In the worst-case scenarios, its blossoms will be too high, making it impossible for you to enjoy the beauty or fragrance as one of your flower bed ideas.
Can lilacs be severely pruned?
A: There are a number of potential causes for your lilac’s failure to bloom. The two most frequent culprits are insufficient sunlight and poor pruning. 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 couple of weeks of the plant blooming, pruning must be done in order to prevent the removal of the buds for the next year. You can softly clip young lilacs to keep them in check, within boundaries, and flowering profusely. In order to revitalize older plants and increase flower production, a rigorous pruning almost to the ground may be necessary. 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. One year, hard prune half of the shrub’s stems; the following year, hard prune the remaining stems.
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. The number of blossoms won’t increase with fertilization. A lilac’s failure to bloom could potentially be due to its proximity to turf that receives frequent fertilization.
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.
How is a lilac tree cared for?
Lilac trees don’t require much care as they develop, but a little bit of maintenance will enable them to reach their maximum size and produce more of those wonderful blooms. The following are some steps to take when caring for lilacs:
- Apply a thick layer of mulch every year to keep moisture in and keep weeds under control.
- The common lilac trees should not be watered until the top is completely dry.
- Sparingly fertilize your lilac plants. A quality fertilizer applied in the late winter will be adequate for the remainder of the year.
- When it comes to caring for lilacs, correctly pruning them comes first on the list of things to do. Once the blossoms have stopped, trim them. They get stronger than previously as a result of this.
- The plant will produce more blossoms if you deadhead lilacs. Additionally, it will enhance the appearance of the plants.
- Keep grass away from the lilacs’ roots to encourage better flowering.
What height are ideal lilacs?
The second or third year of growth is when many of the newer lilac cultivars may need to be pruned because of how swiftly they develop. A stem should typically be clipped when it has a diameter of more than 2 inches. If you diligently prune your lilac shrub every year, it will reach a height of around 8 feet and have blossoms on all of its branches.
Just after the spring flowers have faded is the ideal time to prune established lilac plants. Lilacs produce bloom buds for the following season relatively promptly, therefore late pruning will result in the loss of flowers for the following season. Early pruning also provides young shoots more time and energy to grow, resulting in a spring with many of blossoms.
Liqueur trees dormant or not?
I had a variety of roles as a founding worker at Gardener’s Supply over the years. I currently run my own business, which is called Johnnie Brook Creative. A huge vegetable garden, a seasonal greenhouse, a cutting garden, perennial gardens, a rock garden, a shade garden, berry plantings, numerous container plants, and a meadow garden are among the gardens surrounding my Richmond, Vermont, home. The garden is the only place I would rather be. Check out this Garden Gate magazine video interview from January 2021 if you’re interested in learning more.
Among all shrubs, lilacs are among the easiest to maintain. Their requirements are straightforward: lots of sunlight, excellent drainage, nutritious soil, and yearly pruning. The only maintenance you’ll need to perform is yearly trimming to preserve a great shape, so pick your planting location wisely. You’ll be rewarded with bouquets of scented blooms in the spring.
Lilacs can be planted either in the fall before the ground freezes or in the spring after the earth has thawed. Lilacs are frequently supplied bare-root and dormant in the spring. The plants are merely “sleeping,” not dead. When the roots arrive, take off any packing and soak them in lukewarm water for 10 to 15 minutes. Read How to Plant a Bare-Root Tree or Shrub for planting guidelines. Lilacs are also available in containers. Read How to Plant a Tree or Shrub for details on planting procedures.
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.