The lilac bush, also known as common lilac or by its Latin name Syringa vulgaris, is a flowering, deciduous shrub or small tree native to areas of Europe and Asia. The bush reaches up to 15 feet in height with a spread of 12 feet when fully mature, and produces clusters of large, fragrant flowers in shades of purple, pink, blue and white, depending on variety. Hardy in USDA plant hardiness zones 3 through 7, the lilac bush thrives in most areas of the United States with only minimal care.
Site and Soil
Choose a planting site for your lilac bush that receives full sunlight throughout the day. Lilac bushes tolerate partial shade in warmer areas, but will not bloom as profusely. Ensure the planting site consists of well-drained, moist, fertile soil for optimal growth. Plant lilac bushes in midspring or early summer to allow enough time for the roots to become established before winter. For the best results, space lilac bushes at least 10 feet apart.
Watering and Mulching
Water your lilac bush once per week during the first month of growth to help establish the root system. Reduce frequency thereafter to once every two weeks, except during periods of extreme heat or drought, when the plants should receive water once or twice per week as necessary. Do not allow excess water to accumulate around your lilac bush, or the crown may rot.
Apply a 2- to 3-inch layer of mulch over the ground surrounding lilac bush to deter weeds, insulate the soil, improve moisture retention and gradually add nutrients to the soil. Chopped leaves, grass clippings and pine straw are all ideal mulches for lilac bushes. Replenish the mulch whenever necessary to keep it at least 2 inches thick throughout the year.
Fertilizing and Pruning
Fertilize lilac bushes twice per year, once during early spring before active growth begins and again immediately after flowering ends to help the plant recover. Use an all-purpose 10-10-10 NPK fertilizer to provide adequate nutrition for root formation and flowering. Water after fertilizing to release the nutrients into the soil and prevent root burn. Apply fertilizer according to the manufacturer's directions for the best results.
Prune bushes once every year during late winter, just before active growth resumes in spring. Trim away a third of the oldest growth from the bottom of the plant each year to encourage the growth of new stems from the base. Remove any diseased or damaged stems as well to improve the overall health of the plant. Dispose of diseased stems by burning them in a remote location to prevent the spread of the illness to other plants.