Ripe Sourdough Starter: What does "ready to use" look like?

Sift’s Spring issue goes into sourdough baking in depth, with articles on sourdough breads and the sweet side of sourdough. To complement those recipes, we’d like to share this Techniques column. How do you know when your sourdough starter is ready to bake with? Let’s take a look.
We’ve answered hundreds of questions on this topic, but in this case it seems some pictures could well be worth a few thousand words.
sourdough Starter

Wake up your sourdough starter

Your starter has been tucked safely in the refrigerator for… awhile. Ten days, maybe longer. It’s separated, with a few tiny bubbles in the bottom, and a layer of grayish-looking alcohol on top. This is the sight that generates a lot of phone calls to our hotline. Can this possibly be OK? Is it dead?

Despite its current uninspiring appearance, this starter is still capable of doing great things.

sourdough Starter

Your sourdough starter’s first meal

Stir everything back together (some people just pour off the top layer, which is OK, too), discard half, and feed the remainder with equal weights of flour (a scant 1 cup, 4 ounces) and water (1/2 cup, 4 ounces). Mix well, cover, and leave on the counter for 12 hours. Repeat the discard and feeding process every 12 hours, leaving the starter on the counter. After a few feedings, you’ll see the starter becoming more and more active, doubling in size in a shorter time.

Looking for ideas of what to do with that discarded starter? Visit this page to get a whole collection of recipe ideas.

sweet sourdough baking via@kingarthurflour

Get ready to bake

This is the same starter after a few days of the regular feedings described above. We stirred, discarded, and fed it with flour and water at 8 a.m. (2 hours ago). Now we’re going to watch its development. See the number and size of the bubbles increasing?sourdough starter via@kingarthurflour

Active, but not ripe, sourdough starter

The same starter at 1 p.m., 5 hours after feeding. It’s beginning to expand, and has many more bubbles. If you watch it for a minute, you can see the bubbles forming and coming to the surface in slow motion. This is an active starter, growing and expanding, producing bubbles of carbon dioxide. But it’s not yet ripe (at the top of its yeast and bacteria growth arc), nor at full strength for raising dough.sourdough starter via@kingarthurflour

Ripe and ready to go

The same starter at 4 p.m., 8 hours after feeding. It’s doubled in volume, and shows signs of just beginning to sag under its own weight. This is active starter that’s also ripe, ready to be added to bread dough to perform its sourdough magic. After mixing it into dough, then some rising and folding, the dough can be shaped and refrigerated overnight to be baked tomorrow.

sourdough Starter

The best way to measure sourdough starter

An important thing to note about measuring sourdough starter: The more bubbles in it, the less a cup of active, ripe starter weighs. Measuring by volume can mean you have more or less starter in your cup, depending on where it is on its growth curve. That’s not a deal breaker for your recipe, but having a different amount of starter than called for may change the rising times and finished size of your loaf. To be sure you have the lifting power you need, measuring ripe starter by weight is always a better choice.

Once you gain confidence that your starter is vigorous, you can move its “get ready” feeding to the evening, knowing your starter will be ripe next morning to mix into your dough.

Your sourdough baking adventures await. We have lots of ideas (more than 150 recipes) to help you navigate this tasty and rewarding style of baking. Be sure to visit our sourdough guide for more in-depth information about creating, maintaining, and baking with sourdough.

At Sift, we live and breathe baking, and hope you’ll join us. Baking together is always more fun.

Susan Reid

Chef Susan Reid grew up in New Jersey, graduated from Bates College and the Culinary Institute of America, and is presently the Food Editor of Sift magazine. She does demos, appearances, and answers food (and baking) questions from all quarters.


  1. Teresa Adams

    After using the ripe starter in a recipe, when is it safe to place the remaining starter in the refrigerator? Do I feed it first and let it begin to bubble, or just place it in the fridge right after using it??? Thank you!

    1. The Baker's Hotline

      Hi there, Teresa! After you’ve used some of your sourdough starter in a recipe, you’ll want to feed what you have left and then give it a couple of hours at room temperature to start fermenting before returning it back to the fridge. Happy baking! Morgan@KAF

  2. Stephanie

    I’m confused by the “ripe (fed)” starter that the recipes call for. Does that mean that when the starter is ripe, I should discard all but the 1/2 cup, feed it and use the newly fed starter right away, or should I use the starter that has been sitting and is bubbling and not feed it?

    1. The Baker's Hotline

      Hi there, Stephanie! Ripe (fed) sourdough starter is starter that is bubbly in appearance, about doubled in size and has likely been fed within the last 4 to 8 hours — this can be used in recipes calling for ripe starter. If your starter is no longer bubbly, has deflated or has been stored in the fridge for a few days, it is considered discard (unfed) and you’ll want to remove a 1/2 cup and feed it. We hope this helps clarify and happy baking! Morgan@KAF

  3. Caroline Rash

    How long after a starter becomes ripe can you still bake with it? Mine is ripe but I don’t have time to start working on it tonight. I fed it 7 hours ago and it is peaking now. Will I have to discard and start over tomorrow?

    1. The Baker's Hotline

      Hi there, Caroline! Once your starter reaches its peak it will start to collapse and be less active, making it more suitable for a recipe that is calling for unfed (or discard) starter than ripe (or active) starter. If you won’t be able to get to it until a few hours after it’s peaked, you’ll want to feed it again and let it rise. We hope this helps clarify and happy baking! Morgan@KAF

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