How often do you need to feed your starter? Every other week is probably fine—longer than that, you might start to see it turn pink and slimy. The short answer is that you’ll know it’s dead if you feed it and nothing happens.

And if you’re asking why you should periodically discard some of the starter even in the midst of a flour shortage, it’s because as the yeast feast and multiply, there’s more competition for the flour you’re adding in. You need to make sure they’re getting plenty to eat, even if that means thinning the herd a bit. Plus, unless you’re planning to open a bakery, you’ll wind up with way more starter than you need.

Once you have a starter going, you can keep it in your fridge indefinitely, long after the coronavirus crisis has passed, as long as you continue to cultivate your little colony of yeast and bacteria by periodically feeding it fresh flour and water. I’ve kept my starter alive for about a year now; the starter at renowned Paris bakery Poilâne dates to 1932; San Francisco’s Boudin sourdough starter dates to 1849.

But after you put your starter in the fridge, it becomes dormant, and loses some of its leavening power. When you’re ready to bake a loaf, you’ll need to pull your starter out about 12 hours in advance and reactivate it with a fresh feeding. That will transform the starter into levain, which you can then use as an ingredient in your bread dough (or pizza, focaccia, bagels, or any other leavened dough!), along with flour, water, and salt. Here’s my recipe. Make sure to save a bit of the levain, which you can then put back into your jar of starter in the fridge. And repeat!

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