Q.My French Lilac Shrub Hasn’t Bloomed In 15 Years. What Should I Do???
It bloomed the first year. Then I replanted it.
Certified GKH Gardening Expert
It likely doesn't like its new spot. You may need to change locations. I would also test the soil for nutrient deficiencies or pH swings.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-plant-fertilizer.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/transplanting-lilacs.htm