How to feed your sourdough starter: ratios, timing & troubleshooting

What a feeding is, in one sentence

A feeding is when you take a portion of your starter, combine it with fresh flour and water, and let the colony multiply on the new food supply. That's it. Everything else — the ratios, the timing, the tantrums — is details around that core idea.

The numbers are written as three-part ratios: starter : flour : water. A 1:1:1 feeding is 20 g of old starter, 20 g of fresh flour, 20 g of water. A 1:5:5 feeding is 10 g of starter, 50 g of flour, 50 g of water. You keep the flour and water weights equal (that's what “100% hydration” means for a starter). You change the ratio of old-to-new to control how fast the starter peaks.

How to read peak activity

A starter is at peak when the colony has consumed most of its fresh flour, gas production hits maximum, and the structure starts to collapse on itself. This is the moment to bake with it, or to feed it again.

The three peak signals:

• Volume. It has roughly doubled, sometimes tripled, from when you fed it. Mark the jar with a rubber band at the fresh-feed line and watch the climb.
• Surface. The dome is flat or just starting to dimple. A fully collapsed, caved-in surface means you're past peak.
• Smell. Bright, tangy, faintly sweet, like yogurt. If it smells sharply acidic, alcoholic, or like nail polish remover, it's past peak and is running on fumes.

The float test — dropping a spoonful into water to see if it floats — works, but it's a crude indicator. A collapsed, over-ripe starter can still float because it has plenty of gas trapped in dead matrix. The visual cues above are more reliable.

The three feeding rhythms

You don't need to feed a starter “once or twice a day” in some universal rule. You need to match the feeding rhythm to where the starter lives and how often you bake.

Counter, active baker (baking multiple times a week): Keep it at room temperature. Feed once a day at a 1:5:5 ratio. Or twice a day at 1:2:2 if your kitchen is warm. Keep it around 30–50 g total so you aren't throwing away much flour. Discard or bake with the excess before each feeding.

Fridge, weekend baker: Feed it at 1:3:3 or 1:5:5, let it start rising at room temperature for 1–2 hours, then park it in the fridge. Cold slows the colony to a crawl — you'll need to refresh it once a week. The night before you bake, pull it out and do 2–3 counter feedings to wake it back up.

Dormant, very occasional baker: Dry it. Spread active starter thin on parchment, let it dry at room temp for 2–3 days, then crumble and seal in a jar. Dried starter lasts for years. To revive, mix a teaspoon with equal parts flour and water, feed every 12 hours for 3–5 days, and you're back in business.

The minimum weight rule

A lot of home bakers keep hundreds of grams of starter and toss most of it every feeding. You don't have to. A mature starter is perfectly happy at 20–30 grams total. Keep 10 grams. Feed 10:50:50 when you need more. Before a bake, scale up one feeding cycle to produce exactly the weight you need, plus a little for seed.

This matters for flour waste. A daily 1:1:1 feeding on 50 g of starter throws away 50 g of flour every time you feed. A 1:5:5 maintenance feeding on 10 g of starter throws nothing away — you just build up what you need for a bake. Over a year that's kilograms of flour.

The starter feeding calculator gives you the exact ratio math for whatever starter weight you want to keep and whatever next-feed target you need.

When the starter won't rise

“My starter isn't rising” almost always comes down to one of four causes. In order of frequency:

1. Cold kitchen. A starter at 18°C will feel dead compared to the same starter at 24°C. Peak time roughly doubles for every 10°C drop. If your kitchen sits at 18–20°C, move it to a warmer spot (top of the fridge, inside the oven with the light on, a proofing box). This is fix #1 and solves the problem half the time.
2. Too dilute. If you skipped feedings and the jar sat half-full with old starter for days, the colony is underfed and the acidity is too high. Do 2–3 tight feedings back-to-back (1:1:1, then 1:1:1 again, 4–6 hours apart). It will usually come roaring back.
3. Chlorinated water. Heavy municipal chlorination can stress the yeast and bacteria. Leave tap water uncovered overnight to let chlorine dissipate, or use filtered water. Chloramine (rare) needs a carbon filter.
4. Dead flour. Very old, high-heat-processed, or bleached white flour can lack the wild microflora that keep a starter interesting. Blend in 10–20% whole rye or whole wheat flour for a few feedings. Whole-grain flour brings life into a sluggish starter faster than anything else.

If none of those work, the starter probably isn't dead — it's just been sitting discouraged for weeks. A 3-day rescue with twice-daily feedings at 1:1:1 with 20% whole rye almost always resurrects it. Starters are genuinely hard to kill once established.

The liquid on top (hooch)

A dark brown or grey liquid pooling on top of a neglected starter is called hooch. It's just alcohol and water, produced after the yeast has run out of food. It's not a sign the starter has died. Pour it off (or stir it in for a more sour starter) and feed normally. The colony is hungry, not dead.

If the liquid is pink, orange, or you see fuzzy mold on the surface, that's different. Those are genuine contamination signals. Toss the whole jar, wash your tools in hot soapy water, and either dry a reserve you made earlier or start a new one from scratch using our starter-from-scratch guide.

Changing flours

You can feed a starter on almost anything, but different flours produce different flavors and peak speeds:

• Unbleached all-purpose or bread flour: neutral, predictable, slightly slower peak. Most common maintenance choice.
• Whole wheat: 10–20% faster peak, earthier flavor, slightly more sour because of higher enzyme activity.
• Whole rye: fastest peak of common flours, strong resilient starter, pronounced tang. Great for rescuing a sluggish colony.
• Einkorn / spelt: slower than wheat, milder flavor. Pretty starter; test before relying on it for big bakes.

Transitioning a starter between flours takes 3–5 feedings at the new ratio. The microbial population shifts to match the substrate. Changing abruptly won't harm the starter, but its behavior will stabilize after a few feeds on the new flour.

References

1. King Arthur Baking Company. Sourdough Starter: Maintenance, Feeding, and Troubleshooting. kingarthurbaking.com
2. Forkish, K. Flour Water Salt Yeast. Ten Speed Press, 2012. Chapter on building and maintaining a levain.
3. Robertson, C. Tartine Bread. Chronicle Books, 2010. The Tartine starter protocol.
4. De Vuyst, L. & Neysens, P. The sourdough microflora: biodiversity and metabolic interactions. Trends in Food Science & Technology, 16(1–3), 2005. Peer-reviewed review of starter microbial ecology.
5. Hamelman, J. Bread: A Baker's Book of Techniques and Recipes. 2nd ed. John Wiley & Sons, 2012. Professional-production levain management.