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┬ádays, 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. Bree

    Hi! So how long does a starter stay ‘ripe’? I’ve noticed that when my starter is ready, a few hours later it deflates- is it still ripe or do I need to start over? And how long can a ripe starter stay in the fridge until it needs a ‘wake up’ feeding?

    1. The Baker's Hotline

      Hi there, Bree! Sourdough starter doesn’t stay ripe for long, it is a small window of time that you’re looking to capitalize on for a nicely leavened loaf. Once the starter starts to deflate, it can still be used in a recipe but won’t be quite as strong or quick to leaven your dough as it will be when it’s at peak ripeness. Once the starter goes into the fridge it will become dormant because of the cooler temperature, so even if the starter is just in the fridge for a day it still needs to be fed as it will have deflated and become hungry again. We hope this helps and happy baking! Morgan@KAF

  2. Grace

    I have a starter I started around Christmas 2018, and I’ve slowly gone from an obsession involving commercial yeast breads that began around Thanksgiving 2018 to a curiosity about using sourdough for all types of yeast baking (pan/loaf bread, other flavors/ingredients, etc.). After reading lots of blogs on sourdough starters, several articles on just using the amount leftover in the jar instead of discarding at each feeding, including the Flourish article on keeping a minimal amount of starter.

    I usually keep a very small amount of starter at a cool temp (I live in the Midwest and it’s been a very cold winter and internal temps have been a little cooler too, especially closer to windows), feed it approx. every 24 hours, and let it grow from 30 grams to about 130-150, without discarding, just increasing feeding amounts every day, and then building the levain to the amount needed for my once/twice weekly baking. Sometimes, I may do a 2nd feeding if I don’t think the fallen starter won’t last until the next morning, and just move the feeding schedule later in the day to space feedings.

    I have a couple questions:

    1. What happens if I use the starter before it reaches its peak?

    I know that it’s best to use the starter at its peak, which for my starter is when it’s just over doubled in volume. Mine has gotten as big as 2.5 times, so if it’s doubled, then I see it as close to “peak” and it takes anywhere from 4-8 hours to peak. But sometimes…like tonight, I got a little impatient and I waited about 2.5 hours until the levain/starter volume I was growing for a challah recipe reached about 1.7 times its original volume, so it wasn’t at peak, either by time or by volume. But it passed the float test and when I pulled the edge away from the container, there was evidence of a well-fermented dough/starter, with lots of bubbles being stretched btwn the gluten strands.

    But now, the dough still feels heavy and isn’t puffing up much about 2 hours into the bulk ferment (recipe said at least 6 hours in a warm place which made me nervous with the eggs in it, so I figured I’ll leave it on the table and put it in the fridge overnight before bed). DID I MIX THE DOUGH BEFORE THE STARTER WAS AT PEAK/READY? It’s a challah dough, so it has several eggs and some vegetable oil, and I added the zest of 2 small oranges. I’ve made enriched dough with sourdough but followed a specific recipe that called for building a sweet stiff starter first. This recipe didn’t…just said to use regular starter.

    2. Wouldn’t the sourdough starter at any stage–unfed, rising, peak, falling–once mixed into the dough, start eating through and fermenting the entire dough, flour and water being 2 of the main ingredients? If so, why does it matter that the starter is a peak? Wouldn’t a smaller number of organisms just take longer to ferment the entire dough/prove it?

    1. Susan Reid, post author

      Hi, Grace. You ask some great questions here. As you’re obviously discovering, using your starter before it’s at its 90% peak level (your instincts about this are right on, by the way) will slow down how quickly your dough rises. This is further aggravated by the fact that you put your starter into a high-fat, slightly sweet enriched dough, which is going to be a slower mover anyway. Using the starter before its peak isn’t a deal breaker, but you’ll have to accept that the dough will take longer to rise; you might want to give the dough a couple of folds and an extra hour between mixing and shaping. The finished product will be slightly more sour, since the lactic acid bacterial will have had more time to do what they do.

      As for your second question, any starter that has any living yeast in it will eventually replicate itself to the point of exhausting the available food supply, given enough time while kept within the appropriate temperature boundaries. There are costs to this, however. Unfed starter in a full dough recipe could take as long as 2 days to fully ferment the dough, and while that’s happening the starches in the dough are being consumed, the dough is becoming more and more acid, the gluten is degrading, and some of the carbon dioxide you’re trying to capture is going to be lost. The result of a bread made that way would be a flat, sour, probably gummy loaf. The beauty and challenge of sourdough baking is in learning how to interact with your living culture and your dough so as to get the best results. Consider it more like a dance: the right step at the right moment creates a thing of beauty worth cherishing. Susan

  3. Sam

    My sourdough starter is 100 percent whole wheat it doubles in size after feeding but it does not triple like yours did but it is not bubbly or frothy even the bubbles on the sides are very less and small. It is very dense like a levain. I have seen that other sourdough starters are very runny. What should I do. Im losing hope on making a sourdough bread

    1. Susan Reid, post author

      Sam, a starter that doubles after feeding is a happy, healthy starter. A 100% whole grain starter is never going to get as high as a white flour starter. The sharp edges of the bran cut the gluten strands in the dough, inhibiting its rise. The bran also soaks up more of the water, which is why your whole grain starter isn’t getting as runny or “loose” as a white starter. Feed your starter, use it in your bread when it’s just shy of doubled, and you should have good results. It’s fine; you just have to adjust what you think it should look like to fit its whole grain profile. Susan

  4. Shirley

    I would like a recipe that does not take so much flour, I. Other words a smaller recipe. Thank you for all your help.

  5. Pat

    I use my starter once a week. When i take it out I weigh out the 4 ounces add my flour and water and when it doubles or triples feed a second time then it usually triples in about 3 to 4 hours then I use it. Generally I am making some kind of no knead bread so this allows me an overnight before baking. I am confused by the 12 hour direction. Mine would be all over the counter, and has been when I forgot to watch it. Am I doing something wrong?

    1. The Baker's Hotline

      It sounds like your starter is just super vigorous, Pat, so nothing’s wrong. It’s just active! Annabelle@KAF

  6. Deidre

    Newbie here … When you say in 1st Feeding above, to “discard half” do you mean to pour off the top liquid and then remove half of what is in the jar? Thanks!

    1. The Baker's Hotline

      Hi Deidre! You can stir the liquid back in first, then discard half. If you prefer to have a less strong flavor, pour off the liquid first, then stir it and divide it in half. Up to you! Annabelle@KAF

  7. Summer

    Hi there! My start is currently in the fridge and I’ll need to wake it up to bake. But I may be baking alot over the next few weeks. What do I do to keep it maintained on the counter through that time? I’ll be baking every few days, not enough time to refrigerate and wake it up again.

    1. The Baker's Hotline

      Hi Summer! When stored at room temperature, you’ll want to feed your starter twice a day, roughly 12 hours apart. Our Sourdough Guide offers details and tips on how to keep your starter healthy and bubbly. Happy sourdough baking! Annabelle@KAF

  8. Kate Evans

    I am new to all this and wanted to make my own yeast starter. I have a good starter finished. However, your sourdough recipe calls for adding instant yeast . Why isn’t starter yeast? I wanted to get away from having to buy yeast.

  9. RK

    When measuring out ripe starter for a recipe, do you mix the starter down first and then scoop & weigh that? Or simply dip in to the top of the ripe, bubbly starter and use that?

    1. The Baker's Hotline

      Hi there, RK! If you are weighing the starter no need to stir it down first, but if you are using volume you’ll want to stir it first to get a more accurate measurement. Happy baking! Morgan@KAF

  10. Natacha

    Hi. My starters are over a month old. I’ve been getting great boules of sourdough out of them but was wondering is it best to use the starters when they are at full peak or have fallen? Does it make a difference? Thank you. I love King Arthur!

    1. The Baker's Hotline

      Hi Natacha! You’ll get the best rise using the starter at its peak ripeness, but you would potentially get more flavor using the starter after it’s begun to fall. Annabelle@KAF

Post a comment

Your email address will not be published. Required fields are marked *