The most common species of lilac (Syringa vulgaris) is a welcomed site in the spring. Their beautiful fragrance is unparalleled. Lilacs come in many sizes and colors. The flowers come in either single or double blooms and include many shades of pinks, purples and white. Lilacs range from small shrubs to trees that can grow up to 30 feet tall. They are U.S. Department of Agriculture hardiness zone three to seven.
Lilacs shrubs need full sun, good drainage and fertile soil and should be planted in the spring. They are typically shipped dormant with bare roots and no leaves or buds. They can be bought as started shrubs at a local nursery.
Plant site is very important. Lilacs do not like to be planted near large trees. They need to be spaced about 10 feet apart. Lilacs love sun and should receive at least six hours of sun a day. They also need good soil drainage. Lilacs need a hole deep and wide enough for their root system.
A bare root shrub should be planted with the top layer of roots a few inches below the surface. If it has a root ball, then the root ball should be level with the hole.
Lilacs need fertilizer at the base of the plant each spring to provide nutrients for the coming year. Buds develop the previous year, so fertilizing in the spring feeds this year’s foliage and next year’s blooms. Mulch is recommended to keep moisture in the soil and reduce heat stress. The blooms should be cut off within a week after they fade. This will help the plant concentrate on more buds. If a lilac becomes too tall with sparse blooms, they be can revived by cutting 1/3 of all main steams with a diameter of at least 1 1/2 inches.
The Japanese lilac tree is very similar to the shrub varieties with a few exceptions. It grows more upright, has a wider trunk and can grow up to 30 feet. They have creamy white flowers that bloom in early summer, usually after the other lilacs are done. The flowers are similar to the common lilac but somewhat smaller. The tree should be protected from wind and damage that can be caused by other natural sources. The wood of the tree is softer and damages more easily. The tree should also be planted in full sun. With proper care these trees can survive for almost 100 years.
Insects and Diseases
Lilacs do experience problems with some insects and diseases. Bacterial Blight is a disease that appears where there is temperature fluctuation in the spring along with cold rains. Dark spots appear on leaves and will eventually wilt and turn brown. Flower buds can also be affected. They will turn black. Copper sulfate spray mixtures can be used, but it is better to cut off the affected areas. The cutting shears must be dipped in 70 percent alcohol before used on other plants.
Lilac leaf minor is a moth that lay eggs on lilac leaves. Once they hatch, they begin to eat the leaves. The leaves become black, and, if pulled apart will reveal little, pale, green worms. The best way to get rid of leaf minor is to hand pick and destroy the infected leaves. Sprays and dusts are not very effective because they can miss the larvae that is protected on the leaf.
The common lilac is native to southeastern Europe. There are thousands of cultivars, which are of French origin. The name lilac comes from the word nilak which is Persian for bluish. In Arabic, nilak became laylak and lilac in Spanish. Lilacs belong to the Oleaceae, or olive family, and then together with the genus syringe (from Greek) includes about 30 species of shrubs and trees native to Asia and southeastern Europe.