I have white Lilacs about to open. The variety is called 'Avalanche' They were supposed to very large, but the more blooms are on the shrub, the smaller they are. I'm not finding them very fragrant.

I'm wondering if the fact I have neutral soil could be influencing that at all. Should I be adding Lime to the soil around them and if so, how often should I do that? Will that improve their performance at all? Improve the fragrance, the vigor? I'm happy with the fact the foliage is without mildew which was a problem with the old Lilacs I had, but they sure did smell more fragrant!