Re: Do purple lilacs smell stronger than white lilacs?Why?

You've asked a very good question, but I haven't been able to find an easy
 answer.  Firstly, you were right in your conclusion that the two colors 
of flower came from different kinds of Lilac bush.  It turns out that not 
only are there several species of Lilac available, but also several 
varieties within each species.  Varieties of the common lilac have been 
selected by plant growers for different colored flowers, among them white,
 purple, pink and blue.  It would seem obvious to think that each color 
flower may have a slightly different odor from another.  However, after 
calling the local plant nursery and looking at a few web pages, I haven't 
been able to find any information on whether the flower odors are always 
different according to flower color. 

Another possibility is that the flowers had been in bloom for different 
lengths of time - the odor may be stronger at a certain time in flowering 
than another. 

A good site about Lilacs is found at http://www.pathfinder.com/@@pj12lgUAkMna4ff@/vg/TimeLife/CG/Books/E15/Html/E15073A.html