Lilacs were planted by some of the early settlers, not just for their beauty but also because of their ability to survive and adapt to most climates. The hardiness of this shrub is evident at old vacant homes.
"Lilacs love it here," says Jerry Goodspeed, Utah State University Extension horticulturist. "Even when ignored for several years, they continue to survive and bloom. Lilacs do best in neutral to alkaline soil, which is what we have here in Northern Utah. Many other plants want an acid soil, which can cause problems."
They are also easily adaptable to the landscape, Goodspeed says. They can be used as an informal hedge, specimen planting, background shrub and at times as a focal point. Lilacs come in a variety of sizes and colors. The old common purple or white lilac has been replaced with more exotic, interesting varieties.
It is estimated that there are more than 800 different cultivars of lilacs, he says. With so many available, it can be hard to select just one or two for the yard. "One of my favorites is Charles Joly, which is a dark purplish-red color with a double blossom. Other purples include President Roosevelt, Ludwig Spaeth and Adelaide Dunbar."
A popular white cultivar is Madame Lemoine, Goodspeed says. Pink has become more popular lately. Some of the better pink cultivars are Sweetheart, James MacFarlane and Lilac Sunday. Lilacs also come in blue, magenta, violet and even a creamy yellow color.
"Lilacs need a sunny location with a minimum of eight hours of sunlight per day," he emphasizes. "They can grow in more shady locations, but the bloom production decreases. They like a well-drained soil but can adapt to most soils if not over-watered."
Fertilize the plants every spring with an all-purpose fertilizer, Goodspeed says. They like deep, infrequent watering. If possible, keep water off the flowers when they are setting bud and in bloom. Mulch around the base of the plants to keep the moisture at a consistent level and reduce weeds.
Lilac flowers are produced during the summer, winter over and emerge in the spring, he says. This is why lilacs should be pruned after flowering. If they are pruned early in the spring the flowers are removed and the shrub loses a year of blossoms.
"Lilacs are easy to prune," Goodspeed says. "Simply remove one-third of the older canes right at the base. Doing this every year helps the plant keep its shape and maintain a height of about 6 to 8 feet. Do not top a lilac bush. This causes excess branching at the top, and the plant really starts to look shabby and unnatural."
If the plant has not been pruned for many years and appears to be taking over the neighborhood, a few more of the older canes should be removed, he suggests. This stimulates new growth from the base. Over a three-to four-year period the older canes can all be removed and the newer canes will replace them. This lowers the overall height of the shrub and opens up the center of the plant, allowing better air movement and more comfort for the plant.
For more information, contact your local USU County Extension office.
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Issued in furtherance of Cooperative Extension work, Acts of May 9 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Robert L. Gilliland, Vice-President and Director, Cooperative Extension Service, Utah State University, Logan, Utah. (EP/09-98/DF)