How long does liquid yeast last?

If I were to order up some liquid yeast from AHS, then promptly throw it in the fridge upon arrival, about how long would it stay viable?

the shelf life of liquid yeast is normally 6 months.

its hard to say....maximum viability depends on storage conditions and that's something you cant really control while its being shipped to you.......that being said it should last a few months in the fridge fine once you get it.

what are you making? it may benefit you to look into a dry yeast

definitely read up on making a starter if you haven't already as this will help you overcome less than ideal yeast storage...to a point anyways

if you get it fresh from a reputable source then ya the shelf life is stamped on the package..usually 6 months after package date.

also read up on yeast banking/washing as this will help you if you don't have easy access to fresh/good quality yeast.

I'm definitely going the starter route. I was considering washing what I have going now, but am leaning against it. I think the yeast strain chosen is a very important aspect of the brew itself, and I don't want to choose one that's "close" but not right on.

There is a brew store within reasonable driving distance. I was going to do a fairly large AHS order soon, and figured I'd get the yeast too, just for the convenience of it. I would use it within about 6 weeks tops from arrival, so I figured it would be okay. If it doesn't activate I can always run to the brew store and grab what I need.

Yeast starts to go downhill the minute it is made, but will last a long time if refrigerated. I made a starter with a smack pack that was 2 years old when I first got it ( it was the first liquid yeast I had ever used, about 3 years ago ) and was using it a little more than a week later. You just have to give it more time, like 4 to 6 days to swell, and then make a starter for it.

Liquid yeast is normally good for 6 months but you dont know how long it has been sitting at the brewshop. I make yeast starters and then split them and save them in glass "Yoohoo" bottles. When the time comes, I can pitch the yeast right from the Yoohoo bottles or use them to make a larger starter.

I'm brewing a batch of beer right now with a smack pack of 1084 yeast. It had a date of Mar'07. I did not make a starter, but did let the pack sit for 3 hours at room-temperature before pitching it. It's been fermenting(or not) for 54 hours with no bubbling action through the airlock.

Anyone know how long before I know the yeast was bad?

And by "bad" would that mean the beer is spoiled, or could I add fresh yeast and continue with the fermentation?

Thanks for any thoughts on my questions?

White Labs ans WYeast both have best by dates on them, I would look at those.
But you should be fine for 6 weeks as long as it's fresh, and it should be pretty fresh from AHS.

my last batch was 2months past the Wyeast 'best by' date and it was fine...Make a starter for sure if in doubt.

March 07 is a bit of a strech. The yeast are hardy but....
The best before dates basically say: We guarantee that until this date there will be X number of viable yeast in this dose. That means that the day the packs are shipped they have way more viable yeast than this - and it just declines from there. But if you use a starter to help the yeast "breed" you can ramp the numbers up in an old pack. I have a LHBS that sells out of date smack packs for 80% off regular price. I bought up four of these (various strains) a few months ago and raised up some new healthy yeast that I then plate out onto agar slants and bank for later use. The truth is that there will be some viable yeast in a smack pack that is even 2 or 3 years old but the problem is that some other organisms that like to live in cold, damp, dark environments full of dead yeast may have multiplied in the meantime to the point that making a starter of this stuff will yield a solution full of mystery organisms rather than the yeast that you wanted.

I've used liquid yeast that was expired over 2 years with success.

If you want to make the best beer you can, and i know we all do, yeast health is super important. Whitelabs says that the liquid pack is nearly dead at 4 months - so if you buy 100 billion cells, you likely have 35 billion remaining after 90 days of manufacturing. great site to check is brewersfriend.com Awesome calculator there for yeast counts. A widely desired and accepted yeast count is 150 billion per 5 gallons of 1050 wort. Right off the bat, the liquid yeast is only give you 100 billion and thats at it's freshest date. I would also mention that as your cell count reduces as the pack ages, the stress the yeast cells are under increases. A starter is pretty mandatory (over pitch is way better than under pitch) but realize that if you start with 40 billion stressed cells and use a 1 litre starter, you are likely very short on your pitch rate. good luck.