The purple lilac, scientifically known as Syringa vulgaris, is one of the hardiest plants around. These bushes and trees, left attended, can grow for years on their own, producing some of the most magnificent lavender displays imaginable. Favored for their easily identifiable and soothing scent, lilacs are a staple for many homeowners and landscapers. Used as privacy hedges or as single design element in the landscape, lilacs provide a breathtaking focal point wherever they grow.
Lilacs originated in Asia and Europe hundreds of years before coming to America. According to historian Leon Anderson, the purple lilac was first brought to the U.S. in 1750 from England. It was adopted as the state flower of New Hampshire in 1919 as lawmakers felt it represented the hardiness of the people of the Granite State.
Lilacs adore full sun so a sunny location is a major consideration when choosing a site. Also, depending on the variety of the bush, leave plenty of room for growth. Some can reach heights of 15 feet and spread almost as wide. Well-drained soil is a must. Waterlogged plants don't do well. Adding a little mulch around the base of newly planted bushes for the first couple of years will help keep weeds to a minimum. After that, the growth and density of the shrubs will take care of most weeds themselves.
Lilacs require very little care. They are quite drought resistant and need little watering after the first year. Pruning is necessary only to remove damaged or dead wood or if controlling the shape due to the location of the bush is important. Pruning after the last blooms fade is recommended because lilacs set their buds for next year later in the summer. Pruning after this time will reduce the number of blooms next spring. Never remove more than 1/3 of the bush during any one pruning session.
Lilacs are quite hardy and able to resist pests. Scale insects such as the San Jose scale or the oystershell scale suck juices from the plant, causing an infection which will weaken it. Treat them with a dormant oil spray. Lilac borers prevent water from flowing to the branches properly and can be detected by the appearance of wilting branch and a pile of sawdust at the base of the branch. Insecticides help but the most useful method is to remove the entire branch along with the borer and destroy it.
Bacterial wilt often occurs in the spring when conditions are overly wet. Browning or blackening edges on young leaves followed by wilting of the branch is an early indication. Remove the affected branch, sterilizing the pruning shears with alcohol between snips to prevent spreading the disease. Powdery mildew can cover lilac leaves with a white or gray patch of fungus, usually late in the growing season. It does not harm the bush, merely affects the appearance.