Home of the BrewNosers

I made a starter on Saturday from a jar of washed yeast (Wyeast-1450/Denny's Favorite 50) that Rubbertoe was nice enough to give me last June. Predictably it took a while to get started, but by last night I figure it had pretty much fermented out and I threw the 2L flask into the fridge to settle out.

I'm hoping that the weather will be decent enough on Wednesday or Thursday evening to bang out a brew but if, for whatever reason, I don't get to brew then, how long is that starter likely to remain in good shape in the fridge? I.e., at what point should I throw it back into a jar and plan to make another starter before using it?

I think 1 - 3 weeks is fine.

You lose about 0.7% of the population per day so you can calculate the population decay if you know what you started with. Even if you don't know you can get a close approximation estimating with a low cell count.

I used to order a pack of yeast in and do 4L of starters and dump them into 4 mason jars that i would direct pitch from the fridge for up to 8 weeks.