The fragrant Syringa, or lilac shrub, has been cherished by people throughout history for its lovely purple flower panicles and intoxicating springtime scent. It has been grown in America since colonial times, when it was imported by Dutch, French and English settlers who had loved it in their native lands. Lilacs are easy to care for and are available in a wide variety of sizes, from dwarf to tree size, and with flower colors including white, pink, blue, red, lilac, violet and dark purple. Following some relatively simple guidelines will ensure successful growth of your new shrub.
Consider your lilac's mature size before planting to be sure it will not outgrow its spot. Syringa chinensis or Chinese lilac grows 8-12 feet tall and makes a good hedge plant. Tree lilacs can reach 30 feet with a 25-foot spread.
If your yard is small, try planting one of the smaller Korean varieties such as Syringa patula Miss Kim, which grows to 5 to 8 feet. An even smaller variety is Syringa palibiniana (dwarf Korean lilac), which rarely gets larger than 4 feet.
Find a spot with well-drained soil and full sun, as lilacs bloom best when they get plenty of light. Avoid spots where the lilac will have to compete with trees or other shrubs for water.
Select a plant that is grown on its own roots, rather than being grafted. Such plants are hardier and easier to prune.
Follow the instructions on the plant tag of your particular variety to determine the best spacing. In general, dwarf lilacs should be spaced 4 to 6 feet apart; larger varieties 10 to 15 feet apart. If planting lilacs in a hedge, leave 6 feet between each shrub.
Choose early spring or fall to plant a container-grown lilac; field-dug (sometimes called B & B, or balled and burlapped) shrubs should be planted in spring prior to bud break.
Find a location that has well-drained soil. According the the Arnold Arboretum, lilacs will do well in a soil which is slightly acidic to alkaline. (You can find out where on the pH range your soil falls, and how to amend your soil, by contacting your local county extension service--see Resources). In general, if you notice that lilacs in your area grow and bloom well, yours most likely will too.
Be sure the hole you dig is deep and wide enough to accommodate the shrub's roots without damaging them. The hole should be three times as wide as the root ball, and as deep as the root ball's height. When placing the shrub in the planting hole, the top of the root ball should be 1/2 to 1 inch above the surrounding soil, to allow for some settling.
Water the newly-planted shrub well. Adding a mulch will keep down weeds, help conserve soil moisture, and protect the plant from mower damage. Monitor the plant's water needs carefully until it is established.
Apply a slow-release fertilizer, such as 18-6-12, to the surface of the soil about 4 weeks after planting.