Two Yeast Packs, Different Dates

[Perch06]

I have a Wyeast Smack Pack of American Ale 1056 that I've let go a little long in the fridge. It has a production date of 2/23/2011. According to the Mr. Malty pitching rate calculator, for the ale I plan to brew (OG 1.064) and with yeast from that production date, I would need two packs of yeast in a 1L starter. The other option is to do a 2.34L starter with just the one pack but I only have a 2000ML flask.

So I ordered another pack of the same yeast, but (although it hasn't arrived yet) I assume the production date will be more current. The pitching rate calculator doesn't really account for situations where you have multiple packs of yeast with differing born on dates. Do you think I would be better off just trashing the older yeast and making a starter with the more fresh yeast? Or could I get some use out of the older pack of yeast still? Maybe I could get away with just a 2L starter? Or are there any recommendations for an alternate household vessel besides the flask that could hold more than 2L?

Would there be any value in combining the packs, and if so how would one calculate starter size?

Thanks for the help fine folks...

 

[Pappers_]

You might make the starter with the older yeast, then chill it, decant, add new wort and make a second starter.

I have used yeast much older than yours, the key is to make a nice starter, to increase both yeast health and viability.

 

[dstar26t]

If you want to use the old and new, check the viability of each, add them together and manually put that number in to the viability% input.

 

[Pappers_]

If you want to use the old and new, check the viability of each, add them together and manually put that number in to the viability% input.

For those who have a microscope around the house?

 

[dstar26t]

By viability, I meant the % that Mr.Malty gives you for each pack of yeast based on the date.
Enter each pack's date, record the viability %, add them together, uncheck "calculate viability by date", enter your combined viability % and make your starter.