The common lilac, or syringa, arrived in the United States with the early settlers and has been cultivated for more than 500 years. A deciduous shrub valued for its colorful, fragrant flowers, syringa reaches up to 20 feet tall and requires only basic care to thrive in the home landscape. In fact, many lilac bushes live for years on abandoned homesteads with no care at all. Most syringa varieties survive temperatures well below zero and grow across the United States with ease. Hardy and long-lived, lilacs grow slowly and make ideal plantings for hedges, borders and privacy screens.
Plant syringa during spring, summer or early fall, though early spring planting yields the best results. Choose a planting site that receives at least six hours of bright sunlight and consists of well-drained, moist, fertile soil.
Dig a hole at the site just wide enough to hold the root system without crowding, and 1 to 2 inches deeper than the original planting depth. Insert the roots into the hole, cover with soil and water lightly to initiate growth. Space syringa plants 10 to 15 feet apart.
Spread a 2- to 3-inch layer of mulch over the ground surrounding syringa to conserve moisture, control weeds and maintain a steady root temperature. Replenish the mulch whenever necessary to keep the mulch at least 2 inches thick all year.
Water the plant once per week during the first year of growth to help establish the root system. Reduce watering frequency thereafter to once every two weeks, or once every week during periods of extreme heat and drought. Soak the soil to a depth of 6 to 8 inches at each application for the best results.
Feed syringa once per year, during March or early April, using a balanced 10-10-10 NPK fertilizer. Water thoroughly before and after applying to prevent root burn and release the fertilizer into the soil. Check the manufacturer's directions for proper dosage.
Prune during winter or early spring, when the plant is dormant, to improve both the plant's health and appearance. Use hedge clippers to remove all dead wood, diseased growth, weak branches and suckers, or the horizontal branches that grow from the base of the plant. Suckers sap nutrients from the rest of the plant and do not produce flowers or foliage.