Enjoy the sight and smell of lovely spring lilacs

By Dawn Pettinelli - UConn Home & Garden Education Center
Home & Garden - posted Mon., May. 7, 2012
- Contributed Photo

One of the most delightful flowers of May is the delicately perfumed, fragile, lavender blooms of the old-fashioned lilac, Syringa vulgaris. Lilacs are versatile flowering shrubs with a wide range of uses in the landscape. Try them as specimen shrubs, as a hedge, in a mixed shrub border, or as the backdrop for the flower garden.

While lilac flowers are quite delicate, the plants are among the most hardy, with some species being able to withstand temperatures of negative 60 degrees F. Lilacs are relatively carefree, blooming for many years, even if neglected. They range from 4 to 30 feet high. Lavender-colored blossoms are most common, but lilacs can be found in white, blue, pink, magenta, purple and even yellow.

There are numerous species and varieties of lilacs, as well as extensive hybridization. The old-fashioned lilac is most commonly grown in this country. Blossoms are very fragrant and many beautifully colored cultivars are available (a white variety is pictured above). This lilac can reach a height of 20 feet if not pruned and has smooth, heart-shaped leaves.

Lilacs require a sunny site with good drainage. They prefer the soil pH to be between 6.0 to 7.0, so limestone additions to the soil are often necessary. Plants are generally fertilized once each spring. Mulching will help retain soil moisture and, while drought-tolerant, lilacs will perform better if given water during dry periods.

Pruning is not usually necessary for the first three to four years following planting. After that, remove dead branches and weaker wood from the center of the plant. Overgrown plants can be rejuvenated by removing one-third of the older stems each year for three consecutive years, allowing new stems to take their place. Prune as soon as flowering finishes.

Lilacs have three major pests. Powdery mildew is a fungus which turns the leaves a powdery white in late summer, but generally does not hurt the plants. Non-toxic controls include sprays made from baking soda and the use of anti-desiccants applied as new growth appears. Oystershell scales appear as ashy gray bumps on the stems. These pests are usually controlled with horticultural oil sprays.

Lilac borers burrow into the wood, especially on older stems. A flexible wire can be inserted into each hole, crushing the larvae. The borers often enter the stem just a foot or two above the ground. Look for telltale piles of sawdust around the plant.

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