My lilac bush won’t bloom. It hasn’t for several years.

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

You might have trimmed at the wrong time of year. Only trim lilacs in late spring. They set their buds in the fall for the coming spring. Feed them in the fall. Good luck!

feed them with what ferilizer

Do not trim new growth on your lilac bush because flowers bloom off of it. The best time to trim is right after the bloom. Then Let it grow for next year‘s blooms.

Another thing you might do is cut the bush back to 6-9” above ground. They come back beautifully. No blooms the first year but gorgeous the second!

With your old bushes I’d suggest the second option.

Hello Linda! Lilac bushes typically don’t need trimming. However, if you’ve done that, it is possible that you trimmed at the wrong time of year when buds were ready to bloom. You say you don’t want to get rid of the tree. However, it may be a good idea to replace it with a new, younger bush. That’s what we did at my house and we are happy with the new bush, the new blooms, and the new look. Good luck!

Some varieties require very cold or freezing temperatures for a certain period of time, in order to bloom... I have known several people who put Ice on the roots for several weeks to simulate the cold temps.