Lilacs are one of the most beloved shrubs. Some are classified as small trees, but it doesn’t matter: it’s the carefree flowering, the fragrance, and the low maintenance that is attractive.

Lilacs have come a long way from the traditional purple blooms; you can find lilacs that are in hues of red, pink, blue, yellow, cream or white. Although there are many different species of lilacs; the two most cold hardy varieties are Chinese lilac (Syringa x chinensis) and Early Flowering Lilac (Syringa x hyacinthiflora). Hungarian lilacs (Syringa josikaea) are hardy to zone 5. All of these species can grow eight to 12 feet tall. Because homeowners in urban spaces prefer a smaller plant, breeders have created more compact varieties. So, there’s a lilac for everyone! Even though lilacs are fairly low maintenance, they still need certain things to grow to their full potential.

Critical needs

Pruning is critical. Newly planted lilacs don’t need any pruning for their first two to three years. However, after that, and with more established lilacs, regular pruning is necessary. The focus should be on pruning away old, weaker wood from the center of the bush. This allows for improved air circulation, something that’s critical to prevent disease issues. The pruning window is short for lilacs; only prune right after flowering. Here is a link to a short video on pruning lilacs from the University of Maine Extension: https://www.youtube.com/watch?v=8jyI4-FLRZc

Lilacs have to receive as much sun as possible, six to eight hours. Avoid nitrogen rich fertilizers. Soil must be well-drained. Lilacs also need to be watered deeply during dry spells.

Get your soil chemistry right for lilacs: they prefer slightly acidic to alkaline soil. Let our CCE of Oneida County help you check your soil pH by submitting a soil sample before you plant a lilac. If your existing lilac isn’t doing well, consider a soil test. Find more information about how to take a soil sample by visiting our website at http://cceoneida.com/home-garden/gardening/soils-climate

Why lilacs don’t bloom

If one or more of the critical needs is not addressed, chances are lilacs will produce a lot of foliage but no blooms. Excess shade, lack of proper pruning or pruning at the wrong time, a nutrient deficiency, or lack of moisture are the usual suspects if a lilac fails to bloom or produces very few flowers.

Lilac problems

Powdery mildew disease is the main issue with lilacs. Some of the newer varieties have been bred to be more resistant. If you notice the foliage with a dusty white coating, chances are it’s powdery mildew. The disease is environmentally driven and can be very difficult to control once it has taken over the plant. The disease shows ups during humid summers; it won’t kill the plant but the plant won’t look very nice. Having plants in full sun, along with having good air circulation around the shrub and pruning will help with powdery mildew. You can use a fungicide spray; read the label to insure lilac and powdery mildew are on the label. It’s better to spray as a preventative versus waiting until the disease has appeared and spread. Most fungicides won’t eliminate existing mildew, but they can slow down the spread of the disease.

The National Garden Bureau has named 2022 as the Year of the Lilac. Known as the “queen of the shrubs,” lilacs are wonderful landscape plants. Newer and smaller lilacs such as the variety ‘Baby Kim’ allow gardeners in small spaces to have lilacs. For more information and suggestions on which varieties to grow, visit the National Garden Bureau’s website at: https://ngb.org.

If you missed signing up for the current master gardener volunteer training, we can put you on our list for the next upcoming training. For more information, call us or visit http://cceoneida.com/ and click on Facebook and YouTube icons at the bottom of the page for great research and garden information. Or phone 315-736-3394, (Dial “1” when you hear the recording and then hit x100.)