Q.Asking for help with stinking lilacs
I have the most repulsive stinking lilacs, one in a large pot, the other is a well established bushy tree in well draining soil. Plants are not related (not derived from each other)..stinks of cat piss. Can I change fertilizer, soil pH or watering habits to force the plant to smell more fragrant? I cannot believe these are related to the traditional old fashioned lilacs, so famous for their fragrance.
There are some plants that are known to smell like cat urine to certain people; not everyone is affected by these smells.
Lilac is not generally one of 'offensive plants' on the list.
Perhaps you have a more sensitive olfactory sense.
If you recently added fresh mulch, you can check it. Rake it around to dry it out. Wet, new mulch can often have an odor that produced by the ammonia in the breakdown of the mulch.