Just like the title says: how long does harvested yeast keep? I am assuming to keep the yeast you have to store it in the refrigerator, right?


2 Answers 2


In Yeast (White & Zainasheff), they have a table of the reliable and max shelf life of yeast storage techniques:

  • Harvested slurry: 2 weeks / 6 weeks
  • Agar plate: 1 month / 1 year (if sealed)
  • Agar slant: 3 months / 1-2 years
  • Agar stab: 4 months / 2-3 years
  • Water immersion: 6 months / 3-5 years

… &c., up to professional freezing.

People report success with fridge-stored slurry on much longer time frames. I think White & Zainasheff are being somewhat pedantic; the amount of mutation you'll see in a handful of months is probably both very real, but also not particularly noticable to a homebrewer's beer or palate, all things considered.

You may want to look into yeast washing (using acid to help purify the harvested yeast) if you want to pursue that path.

  • Making a super light ferment occasionally and cropping from the krausen can be a great way to reselect the very healthy yeast strains from the yeast you have been storing.
    – Kortuk
    Commented Sep 12, 2013 at 14:14
  • How do you harvest yeast and store them in a water immersion?
    – anton2g
    Commented Oct 9, 2013 at 15:13

I've been washing yeast for years now and I've never had washed yeast be completely dead, even after 9 months, but that doesn't mean you should necessarily use it. If you do wash yeast, ALWAYS prepare a starter. This will let you know if the viability is good (if it propagates) and smell the starter before pitching. I have ruined two batches by pitching 'off-smelling' yeast washes. I am too cheap to leave the process alone; I have saved literally hundreds of dollars, but even one bad batch really pisses me off... Just remember, any flavors you smell in the starter are going to be in your beer; make sure you like them! Easy enough to run to the homebrew store and by some dry yeast or a smack pack! Good luck.

  • 1
    I have used a few yeasts that make some poor odors during high krausen that do not hold over to the actually beer. Smelling is a good idea, but people should probably compare to previous smells of the same strain.
    – Kortuk
    Commented Sep 12, 2013 at 14:15

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