Lilac bushes are a favorite with homeowners and landscapers. They produce beautiful early spring flowers. The scent of lilacs is admired by many and the blooms make aromatic cut flowers to enjoy indoors. The bushes are long-lived, lasting decades with minimal care. They are drought-resistant and require watering under only the most severe drought conditions.
With more than 20 species of the genus Syringa, lilac bushes can vary in height from 6 feet to more than 30 feet. The taller varieties, like the Chinese lilac tree, can spread as much as 25 feet. Old wood stems can grow to diameters of 12 inches. Their robust growth makes lilacs deal for hedges and borders.
Lilacs traditionally bloom in varying shades of lavender and purple. Some varieties are available that produce white, yellow and even pink flowers. Flowers are produced once a year and bloom in the early spring. Pruning a lilac should be done with care because the buds for next year's blooms begin to develop in the late spring to early summer, just after this season’s blooms have faded. Trimming too much may reduce the number of blossoms produced next year.
Where to Grow Lilacs
Lilacs need plenty of room to grow, so allow 15 feet between individual bushes. For the purpose of growing a hedge, lilacs can be planted 6 feet apart. Plant in well-drained soil with a pH of 6.5 to 7.0. Spring or early fall is the best time to plant lilac bushes. Lilacs can grow in partial shade but prefer full sun.
Care of Growing Lilacs
Lilacs that are growing vigorously do not need fertilizer. If growth has dropped off, a fall application of fertilizer with a 5-10-10 blend at a rate of ½ pound per 25 square feet should help. Pruning each year after blooms have fallen is recommended to stimulate new shoot growth. Remove old, dead wood branches from the center of the bush. This allows better air flow and reduces the risk of pests that prefer to invade dead wood from harming the bush.
Stimulating Flower Growth
Flower production can drop off for a number of reasons. Nearby recent construction may have damaged roots and it will take time for them to recover. If bushes are not pruned after flowers drop, the bush goes into seed production, which requires a great deal of the plant’s energy and results in poor blooms the following year. Pruning just after blooms have faded prevents this. Nearby trees or shrubs may have grown large enough to block adequate sun from reaching the lilac bush. These should be trimmed, or the plant should be moved. Finally, the age of the bush may require “renewal,” a process whereby the bush is cut back by one-third to the ground each year for three years starting with the center of the bush and working outward. After three years, the entire bush is newer growth and will produce better blooms.