Lilacs have been long revered for the heady scent produced by their abundant clusters of flowers. In the 1500s, the shrub was brought from the Persian Empire to Europe. Settlers brought them to North America. New Hampshire even made it their state flower.
While there is a host of magical plants that love the hot temperatures of Southern California, the common lilac is not one of them. There are a few varieties that can take the heat, but most types need more chill hours than the warmer zones can provide.
The proper name for the common lilac is Syringa vulgaris. It is a member of the Olive (Oleaceae) family. Other familiar members include olives (Olea europaea), ash trees (Fraxinus), jasmine shrubs and vines, forsythia and privets.
This shrub may be found as common lilac, French lilac or just lilac.
Preferred USDA Hardiness Zones
The lilac will flourish in Zones 3-7. It originally comes from the Balkan Peninsula in Europe.
Size & Shape
Common lilacs will be anywhere from 8-20' tall and 6-12' wide, depending on what variety you have planted. Pruning can help keep it to a more desirable height. The shape can be irregular, oval or round.
Plant your common lilac in an area where there is full sun. The shrub will grow in some shade, but will likely fail to produce many (if at all) of the prized blooms.
The leaves are 2-5" long and come in either a cordate or oval shape.
They can be blue-green or dark green.
The star attraction of this shrub is its floral display. Highly fragrant flowers are clustered together in a form called a panicle. There are a wide variety of color options available. These days you can find lilacs that have blooms that are purple, pink, blue, white, variegated, picotee and yellow.
Once the flowers have been pollinated, they produce brown capsule fruits.
Design Tips for Common Lilac
Lilacs can be a wonderful addition to your xeriscape. You should not plant lilacs near ash trees, as they serve as a host for ash yellows. This disease is caused by Candidatus fraxinii and will cause the tree to be deprived of nutrients and water. In lilacs, it forms a witches' broom, which can be aesthetically unpleasant. Affected branches can be trimmed away from the shrub.
There are hundreds of lilac varieties available. Check out:
- 'Andenken an Ludwig Spaeth' - purple
- 'Belle de Nancy' - double pink
- 'Krasavitsa Moskvy' - pale pink
- 'Leon Gambetta' - double purple
- 'Miss Ellen Willmott' - double white
- 'Mme. Lemoine' - double white
- 'Primrose' - yellow
- 'Sensation' - purple and white picotee
- 'Wedgwood Blue' - blue
- 'Wonderblue' - sky blue
- 'Yankee Doodle' - purple
Growing Tips for Common Lilac
If your soil is acidic, you'll need to make it more alkaline, as this is what lilacs need. They also need to have soil that will drain properly, lest they have wet feet.
Test your soil before you add any fertilizer. Unless your results show a need for a certain nutrient, you probably won't need to fertilize your lilac some years as extra nitrogen can be harmful.
Lilacs produce suckers, which can be good news or bad news depending on your location and desire. Just nip away any suckers that you don't want to help keep it under control.
Pruning is a must for lilacs if you expect to be able to comfortably reach and enjoy the blossoms. You will want to prune your lilacs just after the flowers are spent so you won't ruin next year's blooming potential. These plants fall under the general guideline of only pruning 1/3 of the shrub each season.
Pests & Diseases of Common Lilac
Lilacs can possibly fall prey to many different pests and diseases, though they are usually not too badly affected. They include:
- Aphids (Aphididae family)
- Citrus nematode (Tylenchulus semipenetrans)
- European fruit lecanium (Parthenolecanium corni)
- Fuller rose beetle (Asynonychus godmani)
- Ground mealybug(Rhizoecus kondonis)
- Lilac borer (Podosesia syringe)
- Mice (Murinae subfamily)
- Oystershell scale (Lepidosaphes ulmi)
- Voles (Arvicolinae subfamily)
- Armillaria root rot (Armillaria mellea)
- Bacterial blight or canker (Pseudomonas syringae pv. syringae)
- Botryosphaeria spp. (causes fungal dieback)
- Botrytis blight (Botrytis cinerea)
- Gray mold
- Nectria spp. (causes fungal dieback)
- Phomopsis spp. (causes fungal dieback)
- Phytopthora spp. (causes fungal dieback)
- Powdery mildew
- Tubercularia spp. (causes fungal dieback)
- Verticillium wilt (Verticillium spp.)
Powdery mildew is especially prevalent on common lilacs. There are varieties available that are less likely to have this problem.