I just tapped a batch of berliner weisse that I made around 8 months ago. It was very slightly tart after primary fermentation concluded, so I added the dregs of a Cantillon. The FG was like 1.003 so I didn't know if there was anything for the dregs to do.
Well it has a very nice lactic sourness now. I don't know if I want to attribute it to the Cantillon dregs or if it just took the lacto a while to really take hold.
I have another berliner that also wasn't very sour after primary that is about 10 months old, but that one autolyzed or something in the keg because it smells like burnt rubber. But it is also tart.
So I am starting to go back on my previous thoughts about commercial lacto, and that if you build up a large enough lacto starter and pitch it either at the same time or slightly before a small amount of yeast, if you have a slight brightness/tartness to the beer right after fermentation is complete, in 6 months or so you should be at a nice level of sourness.
It is more patience than some might think a berliner weisse requires, and much more time than a sour mashed berliner requires, so experimentation is required to find out which character you like more.


