Tip of the Week — 5/11/09

Posted in Gardening Tips on May 11 2009, by Sonia Uyterhoeven

Lovely Lilacs for the Garden

Sonia Uyterhoeven is Gardener for Public Education at The New York Botanical Garden. Join her each weekend for home gardening demonstrations on a variety of topics in the Home Gardening Center.

Lilacs have been a staple of the home garden for hundreds of years. They flourished and were coveted by founding fathers such as Thomas Jefferson and George Washington. The popularity of lilacs comes as no surprise—they are easy to grow, wonderfully fragrant, and produce beautiful, blousy flowers from late April into June (depending on the cultivar).

The common lilac (Syringa vulgaris) is also known as the French hybrids from important hybridizing work that was undertaken in France in the 19th and 20th centuries. This lilac, indigenous to Eastern Europe, is the image we conjure up when we think of lilacs. It has elegant heart-shaped leaves and large, fragrant flowers, typically in white or purple. Another common lilac is the early flowering hyacinth lilac (Syringa x hyacinthiflora). This is a cross between the common lilac and an Asian species. It flowers up to 10 days earlier. It looks very similar to the common lilac and has fragrant single or double flowers.

Tree lilacs (Syringa reticulata) are wonderful disease- and pest-resistant plants. These large lilacs can easily grow up to 20 feet tall. They have creamy white flowers that appear in June and lovely ornamental bark.

Meyer or ‘Palibin’ lilacs (Syringa meyeri) and the Manchurian lilac (Syringa patula) are two dwarf varieties that make excellent garden additions to beds and borders and are often used as screens or hedges. Their height ranges from 4 to 8 feet, and they produce pale mauve flowers in late May to early June. The popular cultivar ‘Miss Kim’ (Syringa patula ‘Miss Kim’) is one of the few lilacs that have a wonderful fall color—a deep burgundy.

For tips about growing lilacs…

Some tips to know about lilacs…

• Lilacs grow best in sites with full sun and good drainage. They prefer soil with a pH between 6 and 7. Once a lilac is established, it is fairly indestructible. They rarely need supplemental water, unless there is a drought. 
• Lilacs will tolerate partial shade, but plants tend not to flower as prolifically. Deadhead lilacs after the flowers fade. Some gardeners leave the spent flower heads on to provide seeds for finches and other birds later in the season. 
• Lilacs flower on second-year wood. Prune immediately after flowers fade, thinning out the stems and removing crossing branches. If your lilac isn’t performing the way it used to, rejuvenate it by cutting out one-third of the old wood for a three-year cycle to encourage vigorous new growth. Smaller varieties such as Meyer’s lilac (Syringa meyeri) and Syringa patula ‘Miss Kim’ rarely need pruning.
• Lilacs often suffer from powdery mildew. Fortunately, they are beset with the problem in late summer after most of the growing season is over. It is a cosmetic problem that doesn’t affect the health of the plant. If it is too unsightly or your plant is in a prominent place, spray with horticultural oil once the problem begins. As always, select disease resistant varieties for your home.