Flanders Red: rack off yeast after primary?

Brewed a flanders red two weekends ago. First attempt at doing a sour. Used Wyeast Roeselare blend. Primary fermentation has finished.

Do I need to rack off the yeast cake, or can I let it alone until it’s finished?

Nope.  Let it condition on the cake for another week or two and then keg or bottle.

I think you will be fine leaving it on the yeast cake.  I would, however, wait with bottling it.  The other critters in the Roeselare blend can take awhile to finish fermenting the beer.  I would suggest waiting a few months before bottling.

I brewed it for a party in October, so it will get at least nine months to sour.  Hopefully, that will be enough.  Then it will be kegged, actually.

I’ve never left a beer on the cake for more than  about two months, so I’m a little wary.  Thanks for the answer and reassurance.

Flanders are generally racked off the trub to a secondary, while Lambics are left on the trub.  You don’t have to rack to a secondary, but it is the traditional way.