My 12 yr old lilac Bush isn't producing many blooms last 3-4 yes. What

try this link --- https://ask.extension.org -- will depend a lot on your grow zone, environment, etc.

https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm

It may be getting woody...have you trimmed it lately? I would trim it to try and promote new growth.

Trim it back then use epsom salt and jobs fertilizer sticks. (Mix gal water with 1 cup Epsom) pour around base of tree then stick 1 fertilizer stick near base.

Although lilacs tolerate a range of soil types, they prefer well-drained, humus-rich soil. Therefore, working compost in with the soil will help create a suitable planting soil for them. They should be watered thoroughly but not too often, as lilacs do not like their roots to become saturated.

Frequent use of fertilizer is not necessary for lilac tree care. However, fertilizing in early spring may help give blooms a boost, provided there is not too much nitrogen, which will result in insufficient flowering.

Soooo, you might want to have the soil tested at your local Cooperative Extension location, or purchase a kit, they are not that expensive.

Yes but you can always put moth balls in holes!!

I am in New England and have sandy soil. When I inquired at the local garden center, they recommended copper powder. Adding copper to the sandy soil helps the lilac to grow better and then produce more flowers. I was skeptical last year, but we have a ton of buds this year. Hopefully they will be open for Mothers' Day.

Several years ago we fertilized our apple trees every year and had NO apples; when we quit they gave us more than enough--this may be what is happening if you done this