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Syringa Vulgaris: Growing Lilacs In The Garden

If you’ve ever come across a large deciduous shrub with dark green heart-shaped leaves and clusters of small purple flowers, then you may have encountered Syringa vulgaris, common lilac. Its most identifiable characteristic, however, is probably its scent. They tend to smell sweet and floral, almost like roses, and their scent carries easily on the wind, wafting through windows in late spring and early summer. 

Common lilac makes a lovely addition to any garden. They are early flowering and provide food for pollinators, including butterflies, in late spring before summer flowers have had a chance to bloom. The color of the flowers can range anywhere from white to various shades of purple, pinkish purple, and magenta. The most commonly available are the purple lilacs. 

Lilacs are known for growing quite tall if given space. Placing them on the north side of the garden, on the sunny side of a building, or as a border along a property line are all excellent uses for this shrub. The syringa species has been widely cultivated and requires low to medium maintenance. Once they are established they will flower profusely for years to come!

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Quick Care Guide

Syringa vulgaris
Syringa vulgaris is a gorgeous plant and well worth growing. Source: anro0002
Common Name(s)Common lilac, English lilac, French lilac
Scientific NameSyringa vulgaris
Days to HarvestFrom seed, 3-4 years for consistent flowering
LightFull sun
WaterDrought tolerant 
SoilFertile, well-drained
FertilizerCompost in early spring
PestsLeaf miners
DiseasesPowdery mildew

All About Syringa vulgaris

Syringa vulgaris starting to bud
Here you can see the flower buds just starting to form. Source: anro0002

The common lilac (Syringa vulgaris) is sometimes also referred to as English lilac or French lilac. They originated from the Balkan peninsula in southeastern Europe. It’s in the same family as the olive tree (Olea europaea) and shares the Oleaceae native range. This deciduous shrub is a perennial which will go dormant each winter and come back with new growth each spring. 

Syringa vulgaris is known for its clusters of purple flowers and blue-green heart-shaped leaves. Lilac can grow to be 15-20 ft tall, and may resemble a small tree but is in fact a multi-stemmed shrub that is known to put out root suckers. These suckers can be dug up and transplanted to another area of the garden for easy propagation. Although it can grow to be very large, regular pruning can help to keep it at a more manageable size. 

Lilacs have a notoriously short bloom time which only lasts a few weeks beginning in mid-spring. It’s best to deadhead them as soon as the blooms are spent so that the remaining energy in the plants can focus on establishing the roots before winter. Common lilac requires a certain amount of winter chill hours to break dormancy in the spring and thus, bloom. For this reason, they’re not easily grown in warm climates. 

While lilac flowers are highly fragrant and beautiful in their own right, they are also edible! The flowers can be used in several culinary applications. The fresh flowers can even be steeped in lemonades and iced tea for a floral flavor. It can be used culinarily in much the same way as dried lavender. Lilac essential oils, however, are often imitations since the process of extracting essential oil is too harsh for delicate flowers.

A deciduous shrub, such as lilac, is a necessary component in creating a landscape for wildlife. These plants provide food, cover, and places to raise young. Although their bloom time is short, the flowers provide pollen and nectar for bees, butterflies, and hummingbirds alike. This food is provided in mid-spring when most other flowers have not yet bloomed. 

During spring and summer when these bushes are full of blue-green foliage they provide cover and nesting sites for small birds like finches and sparrows. In the fall and winter, after their leaves have dropped, they are still able to provide overwintering sites for hibernating insects like ladybugs and solitary bees. They can create a windbreak on your landscape as well since they are extremely hardy. 

Popular Varieties of Lilac

Common purple lilac is the most familiar variety out there. After all, when you hear the word ‘lilac’ used to describe a color, you often think of light purple tinted with pink which is the hue of this widely available plant. The Bloomerang cultivars are an exciting prospect for those who lament the short bloom time of this plant. They begin flowering in May alongside other varieties. They will need to be deadheaded after their initial bloom and after a pause mid-season, they will put on new growth and bloom again in the late summer and into the fall. They add beautiful fall color to the garden late in the season.

For those living in a milder climate and longing for the chance to grow this fragrant flowering shrub, there are botanists producing several cultivars that are able to survive with lower chill hour requirements than that of the standard syringa species. Josee is another variety that is reblooming with a lavender-pink flower. The recommended growing zones for this type are USDA zones 3-8. In milder zones, it’s important to cease watering in the late fall and winter to encourage the dormant period that is necessary for blooming. 

Dwarf Korean is a great option for gardeners who are tight on space. This variety is often pruned to look like a small tree rather than a bush. It has a mature spread of 4-6 ft. This can be beneficial when planting if you don’t have 15ft of space to dedicate to this plant. Madame Lemoine is one of many french hybrids that is known for its white flower blooms. White lilacs are stunning in the garden and smell just as fragrant. They can add interest to a long row of bushes and break up the purple with pops of white. 

Care

Lilac buds developing
A view of lilac buds close up as they start to open. Source: anro0002

As mentioned above, lilacs require medium maintenance. These plants can continue to grow and bloom with minimal care and borderline neglect, but regular pruning will help you get the most out of this shrub. Under the right circumstances, these plants can grow for 100 years! 

Sun and Temperature

When planting your lilac be sure to choose a spot with full sun. These plants require at least 6-8 hours of sunlight per day. It tolerates light shade, but may not bloom as profusely with less exposure to sunlight. The recommended USDA growing zones for Syringa vulgaris are zones 3-7. 

As mentioned above, lilac does best with a certain amount of winter chill hours, generally around 2000 hours spent below 45 degrees. This period of dormancy allows the buds to mature and it will only bloom after the chill requirements are met. This prevents the plant from blooming too early, while it’s still winter, when there may be a rogue warm day in January or February. Common lilacs are known to be extremely frost-hardy (down to -40 degrees) and do best in places with a cold winter. 

Water and Humidity

One of the things that makes lilac so easy to care for is that they are very tough and considered to be drought tolerant. If you forget to water them they will most likely be fine! But for the best results and the most flowers, there are a few best practices to follow. 

This plant prefers moist soil but doesn’t do well if overwatered. Watering it deeply with a soaker hose every two weeks yields the best results. If you live in an area that regularly receives measurable rainfall throughout the spring and summer, then you may not need to water it at all. Once the foliage has dropped and the plant has returned to dormancy in the fall then watering is no longer necessary. Be sure to water at the base of the plant to avoid wetting the foliage as that may cause issues with powdery mildew.

Soil

This shrub can do well in a multitude of soil types as long as it is provided with good drainage. It will not, however, tolerate acidic soil. A soil test may be necessary if you suspect that you have slightly acidic soil which can be amended with the addition of lime. It survives best in the pH range of 6.5 to 7.0. Providing these plants with well-drained, fertile, alkaline soil will keep them happiest. 

Fertilizing

As far as fertilizing goes, all cultivars of Syringa vulgaris can thrive without them. This is another factor that makes them an excellent choice for beginner gardeners, as they require little to no maintenance in this area. Topdressing with compost in early spring is more than sufficient for this hardy shrub. 

Pruning and Training

Regular pruning is probably the most important part of caring for your lilacs. Immediately after the flowers have bloomed, snip back the spent buds to the first leaf node. This will prevent the plant from expending energy on the seed set and will redirect it to root growth. This is also a good time to remove older stems that may have permanent damage or no longer produce flowers. This will allow for good air circulation and create space for new growth in the spring. 

Lilac stems can grow quite thick over time and may require heavy-duty loppers to cut through the bark. Cut them back at the base as close to the ground as possible. Lilacs are also known for putting out sucker shoots, so this is also an opportune time to promptly remove root suckers before they expand further – or don’t if you’d like your plants to spread out! 

Lilacs don’t do well with harsh hedging techniques and do best when allowed to grow in an irregular outline, but regularly pruning back older growth will keep them at a manageable size. Since they grow at a medium rate, pruning may not be necessary each year, but the ideal time to evaluate this is immediately after the plants have bloomed. 

Propagation

As mentioned above, common lilac is known for producing root suckers and if you promptly remove these suckers you can prevent unwanted colonial spread. However, these suckers can also be used for propagation purposes. Dig them up, including their root ball, and plant them out in another full-sun location or give them away. Leaving them in place will allow your plants to branch out and spread on their own. Lilacs can also be grown from seed. However, it will require at least 3-4 years of growth before their first flower will appear. 

Harvesting and Storing

Syringa vulgaris in flower
Syringa vulgaris in flower is a delight! Source: anro0002

Now for the fun part, harvesting your lilacs! The flowers can be cut and admired indoors in an arrangement or, as mentioned above, are edible and have several culinary uses. 

Harvesting

If harvesting for a cut flower arrangement, it’s best to take the flower clusters when about 50% of the buds are still closed. This will allow them to continue to open and last even longer in a vase indoors. When harvesting for this purpose you’ll want to cut a sizeable portion of the stem below the flower clusters. This portion should be cut to the length of your vase. At the base of the stem, place a V-shaped cut so that it can continue to take up water and assist the remaining buds with their bloom. 

On the other hand, if you’re harvesting for culinary purposes, then it’s best to wait until the flowers have opened completely. Cut just below the bottom of the flower cluster. Remove the tiny purple flowers individually from the main stem. This is a great time to inspect them for bugs or other small insects that may need to be brushed off. Refrain from rinsing the flowers with water as they are very delicate. When deciding to consume these flowers please make sure to only harvest from plants that haven’t been treated with any harsh chemicals.

Storing

Lilac flowers are edible and can be used in several different culinary applications. When using the flowers fresh, it’s advisable to use them as soon as possible after harvesting. They can be used to infuse other foods which can then be used to flavor other dishes. A few ways to do this would be to make a simple syrup, lilac-infused honey, or infused sugar. These sweeteners can then be used in baking or stored for future use. Lemon lilac tea cakes, anyone?

For longer-term storage, the flowers can be dried either naturally in a cool, open-air environment or a dehydrator at a very low heat setting. This way they will be preserved indefinitely, but their flavor will decrease after a year of storage. The dried flowers yield the best flavor when steeped in hot water for tea and other beverages. Lilacs can also be candied, but this is a painstaking process due to their delicate petals. 

Troubleshooting

Leaves of S. vulgaris
The leaves of Syringa vulgaris are spade-shaped and lushly green. Source: anro0002

Syringa vulgaris is notoriously easy to care for and therefore an ideal plant for the beginner or gardeners looking to add something relatively low maintenance to their landscape. There are, however, a few issues that may require debugging.

Growing Problems

Waiting too long to prune your lilac may result in an overgrown and unmanageable mess. Removing old and/or damaged branches is paramount to the overall health and longevity of these plants. Pruning helps encourage new growth and more flowers. Older growth tends to flower less and less often until it doesn’t flower at all. Regular pruning also helps provide good air circulation.

Pests

Leaf miners are the most common pest issue for lilacs. They may bore through some of the leaves from time to time, but rarely do any lasting damage to this large deciduous shrub. To prevent their populations from getting out of control, be sure to attract predatory insects like soldier beetles, to your garden. Providing plants with plenty of pollen will attract these beneficial bugs. Soldier beetles eat soft-bodied insects such as aphids, caterpillars, and leafminers alike. In the event of an uncontrolled infestation, neem oil can be used to deter leaf miners. Bacillus thuringiensis, or BT, is also effective against leafminer pests.

Diseases

Powdery mildew is the most common disease to affect Syringa vulgaris. As mentioned above, your greatest weapon in the fight against powdery mildew is regular pruning. Powdery mildew is a fungus that loves hot, humid conditions. Therefore, providing your plants with good air circulation via pruning is the best way to prevent powdery mildew from taking a foothold along with watering at the base of your plants and avoiding wetting the foliage. Wet leaves can also provide the perfect condition for powdery mildew to thrive. Placing a soaker hose at the base of the shrub is an easy way to avoid this.

Most additional disease problems are related to fungal leaf spots. There are a wide variety of fungal causes, such as Alternaria leaf spot, that can cause yellow to brown spots on leaf surfaces. Eventually, the brown spots will collapse and fall from the leaf. Similar to powdery mildew, these fungal leaf spots will thrive in humid, hot conditions, so water at the base of plants to avoid aiding the leaf spot fungi. 

Both powdery mildew and many leaf spot issues can be prevented by regular applications of neem oil. Remove heavily-damaged material from the plant when discovered so the fungal spores do not continue to spread. Treating the remainder of the plant with either neem oil or an OMRI-rated copper fungicide can reduce the chance of reappearance.

Frequently Asked Questions

Lilac about to bloom
Just before blooming, there will be a myriad of buds preparing to pop open. Source: anro0002

Q: Is Syringa vulgaris invasive?

A: No, it is not considered to be invasive.

Q: How fast does Syringa vulgaris grow?

A: At a medium rate.

Q: Where do lilacs grow best?

A: Zones 3-7 in areas with a cold winter in fertile, well-drained soils.


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