More pic's

I;'m not sure this is the problem but the mention of high acid makes me wonder. Lilacs like base not acidic fertilizer and I use vinegar (acid) to kill the shoots that insist on coming up beyond the border I maintain.

How much sun are the Lilacs getting? If they are being shaded it would explain the sparge foliage.

Mike

Given the tree in the pic and the dappled light showing on the lilacs, I believe they are in too much shade. Lilacs need lots of sun. It's heartbreaking to lose plants, I know. But, there are lots of shrubs that will take part sun or part shade!

Pretty shady area...could be the cause.

Lilacs are pretty tolerant of soil conditions but have a preference for alkaline soils....they thrive around here on dry shallow clay soils over limestone (pH 8.3+). I don't recall ever seeing a healthy lilac on acidic soils.

So how are they dong now? You could add lime to the soil to give them more basic conditions. I added some around mine and they really took off! Our soil is fairly neutral. Also using vinegar should not really have caused much problems, since it is organic, in about a week, all the acid would be broken down. Unlike say sulfur, which would stay acidic.

So, they look basically the same this year. I am going to add some lime to the soil and see what happens I guess. I can't imagine it could hurt at this point.

Another thing to try is to rejuvenate the plant by removing the old growth and hope that stimulates new growth. I did that to one of my bushes and I took too much off. Probably only 1/3 should be removed at most each year till renovated. I removed about 1/2 of the old growth and it looks thin, and hardly flowered, still new limbs are forming. They can be seen at the bottom middle.

On a 2nd bush I only removed the oldest branch. it flowered profusely, well is flowering profusely. I just went outside and snapped this photo. Not much new growth though....