Pitching a slurry

I have 250ml of slurry, according to the yeast calculator it says I’m good, no need for a starter. It’ll be 2 weeks old when I use it. There’s no input for a date when using a slurry. Is there a guide to how healthy a yeast slurry stays?

I have used slurry that is a couple months old with no problem. I always let it sit at room temp for a few hours before pitching. Every time I have used slurry that’s several weeks old it does take awhile to start bubbling. Always turns out fine though.


I’d feel confident using 2 week old slurry. To get viability just plug your date in as if it were a new package of wet yeast. It will give you a percentage then just apply that percentage to your slurry and you have viability.

250 ml slurry x #billion cells x viability percent = viability and pitch rate for your slurry.

I use the Brewers Friend viability estimate for liquid yeast, for harvested yeast. I use the date active fermentation began for the production date to input.