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How long can Wyeast sit out?

I had a pack of Wyeast that took a while puff so I used dry yeast instead. It’s been sitting out for three weeks and now has fully puffed. Is it still good, or should I scrap the pack and use dry yeast?

Not sure if it matters, but I’ll be using if in a Bourbon Barrel Porter and have the capability to make a yeast starter.


The yeast is still good. Give it a 10% viability loss as a safety margin. Make your starter according to a calculator that takes into account production date for the viability. I like to use this one.

The Wyeast smack pack doesn’t need to fully expand before it is added to the starter wort. A starter should be made with any liquid yeast for good performance even if it is rather fresh and the beer is low gravity.

My LHBS had one out for months just to see if it would explode. AFAIK it never did. A starter is a good idea though.

Thank you!

Personally, I think that if it took longer than about 3 days to expand the packaging, it is not very healthy yeast, so you would have two options in my view:

  1. Throw it away, or

  2. Nurse it back to health slowly and deliberately.

If you really don’t need the yeast, I think the easiest path is to throw it out and buy new. Better safe than sorry.

FWIW, in general I think liquid yeast has about an 8-9 month life on average in the refrigerator before I just buy new stuff, as to me it usually isn’t worth the hassle to baby it back to life again with multiple pitching steps, etc. On the other hand, for an upcoming clone batch of Unibroue’s La Fin du Monde, I actually plan to baby the dregs of several actual bottles of La Fin to get enough yeast to pitch into a bigger batch of my own wort. (Also I actually plan to split this batch and try the Danstar-Lallemand Abbaye yeast alongside it to see which one turns out better, as a little exbeeriment. But anyway, I digress.)


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