Why won't my Japanese Tree Lilac bloom?

Asked May 9, 2016, 10:04 AM EDT

About five-six years ago I purchased a Japanese Lilac Tree from Bailey Nurseries through the City of Minnetonka as part of their tree promotion for citizens. The tree is planted in my back yard in fairly rich organic soil and receives plenty of sunshine. I keep hoping it is going to bloom but does not. It looks healthy with plenty of foliage but no blossoms. Any suggestions??? Thanks! Bette Neitzke

Hennepin County Minnesota

1 Response

Following are comments from an Iowa State University bulletin. It refers to lilacs in general so some of the information does not apply to a Japanese tree lilac. However, the time needed for lilacs to bloom after planting is relevant.

Although Japanese tree lilacs grow well in Minnesota and often produce billows of fragrant flowers, some years even mature specimens fail to bloom.

"Since lilacs are chiefly grown for their attractive, fragrant flowers, many gardeners are disappointed when plants don't bloom quickly. Lack of flowering may be due to several factors. While Syringa meyeri 'Palibin' will flower when quite small, many lilacs won't bloom for 4, 5 or more years after planting. Lilacs and most woody plants must grow and mature before they are capable of blooming. Exposure also could be a factor. Lilacs need at least 6 hours of sun to bloom well. Improper pruning is another possibility. Many lilacs bloom on the previous season's growth. The flower buds form during the summer months. Pruning lilacs in fall or late winter could remove much of the blooming wood. There is little that an individual can do to encourage lilacs to bloom. Fertilizing the shrubs encourages vegetative growth, but may actually delay flower formation."

Go here to read the complete bulletin:
https://www.extension.iastate.edu/newsrel/2001/may01/may0106.html

Information here may also be of interest:
http://articles.extension.org/pages/39133/i-have-a-five-year-old-japanese-lilac-tree-syringa-reticulata-the-tree-is-in-the-middle-of-a-large-a