How to Feed a Sourdough Starter

To feed a sourdough starter, discard all but a small amount, then stir in fresh flour and water by weight, most often in equal parts (a 1:1:1 ratio). On the counter, feed it once or twice a day. In the fridge, once a week is enough. It is ready to use when it has roughly doubled and is just beginning to fall.

That is the whole routine. The details below help you pick a ratio and schedule that fit your kitchen and how often you bake.

How to feed a sourdough starter, step by step

1. Stir the starter, including any liquid on top.
2. Weigh out the amount you want to keep into a clean jar (or remove the rest from the jar it is in). For example, 50 g.
3. Set the rest aside as discard to bake with, or throw it out.
4. Add flour and water in the ratio you have chosen. For a 1:1:1 feeding, that is 50 g flour and 50 g water.
5. Stir well until no dry flour remains, scrape down the sides, and mark the level with a rubber band.
6. Cover loosely and leave it at room temperature, or let it get going before it goes in the fridge.

Weigh everything. Cup measurements of flour are too variable for a culture this sensitive.

Why do you have to discard?

Colorado State University Extension notes that regularly removing some starter when you feed it is an important step that keeps its volume stable. Without discarding, a starter doubles every day and each feeding has to double too, or the culture gets hungry. Within a week you would need a bucket.

The discard is not wasted. Once your starter is established, use it in sourdough discard recipes such as discard crackers and discard pancakes.

Feeding ratios explained

Ratios are written as starter : flour : water, by weight. The bigger the second and third numbers, the more fresh food the starter gets, the more diluted its acidity, and the longer it takes to reach its peak.

King Arthur Baking uses 1:1:1 as its standard feeding and says a starter fed that way typically doubles and starts to deflate roughly eight hours later. Exact peak times for the larger ratios depend heavily on temperature and flour, so treat them as slower, not as a fixed number of hours. Watch your own starter for a few days and you will learn its rhythm.

Which flour should you feed your starter?

Unbleached all-purpose flour is the most common choice and what King Arthur Baking uses for maintenance. Whole wheat and rye flours ferment faster and give a tangier, more active starter. Many bakers use a mix, such as mostly all-purpose with a little whole grain. Pick one and stay consistent so you can read how your starter behaves.

Counter or fridge: which schedule should you use?

On the counter (if you bake often)

A starter at room temperature eats quickly. King Arthur’s maintenance guide feeds a counter starter every 12 hours (twice a day); its feeding guide says once a day works for regular bakers. Use a 1:1:1 ratio if you feed twice a day, or a larger ratio such as 1:5:5 if you only feed once, so the starter does not run out of food long before the next feeding.

Pros: always ready to bake. Cons: a daily commitment and a lot of discard.

In the fridge (if you bake weekly or less)

Cold slows fermentation dramatically, so a refrigerated starter needs far less attention. King Arthur Baking recommends:

• Feed it at least once a week. Keep 113 g (½ cup) of starter and feed it with 113 g each of flour and water.
• Leave it on the counter for 1 to 2 hours, until it starts to bubble, then return it to the fridge.
• A day or two before you bake, take it out and give it a couple of feedings at room temperature so it is lively again.

Pros: low maintenance and little discard. Cons: you need to plan a day or two ahead, and a starter fed less often tends to taste more sour.

How do you know your starter is at its peak?

A starter is ready to use at or near its peak, when the yeast population is most active. Look for:

• It has roughly doubled (or more) from the rubber band.
• The top is domed or just starting to flatten or sink in the middle.
• It is full of bubbles, including large ones on the surface and smaller ones throughout.
• It has a light, airy, almost mousse-like texture when stirred.
• It smells pleasantly tangy and yeasty, not sharp.

King Arthur describes the right moment as when the starter “has doubled in volume and is showing signs of just beginning to deflate.”

If it has fallen a long way and there is liquid on top, it is past its peak and hungry. Feed it again before you bake.

How to revive a neglected sourdough starter

Forgot the jar at the back of the fridge? King Arthur Baking says even months of neglect usually will not kill a starter. Here is how to bring it back:

1. Check for mould. Fuzzy or coloured spots, or pink or orange streaks, mean it is time to start over. Colorado State University Extension says a starter with any sign of mould should not be used.
2. Deal with the hooch. A layer of grey or dark liquid is normal. King Arthur says you can stir it back in, or pour it off if there is a lot (more than about half an inch).
3. Discard and feed. Keep a small amount, perhaps 25 to 50 g, from below the surface, and feed it 1:1:1 with fresh flour and water.
4. Feed every 12 hours at room temperature until it reliably doubles again. This usually takes a few days. A bit of whole wheat or rye flour helps.
5. Bake only once it is back to its old self. A starter that has not fully recovered will give you a dense loaf.

Can you take a break from feeding?

Yes. A refrigerated starter can go a few weeks between feedings and still be revived, though it will need more coaxing the longer you leave it. Colorado State University Extension notes that a starter can also be dried for long-term storage. The usual way: spread a thin layer on parchment, let it dry completely, crumble it and keep it in an airtight jar. To revive it, mix the flakes with water and flour and feed as if you were starting fresh.

Next steps

If you have not made a starter yet, start with our day-by-day guide to making a sourdough starter from scratch. Once yours is peaking reliably, our sourdough for beginners guide walks you through your first loaf.