How to Feed a Sourdough Starter

A feeding ratio like 1:2:2 means 1 part existing starter, 2 parts flour, 2 parts water — by weight. 20g starter + 40g flour + 40g water = 100g total at 100% hydration. The ratio you choose determines when the starter peaks, how sour the resulting bread will be, and how your baking schedule fits into your day. It is not a detail. It is the control mechanism.

What “feeding” actually does

Your starter is a living microbial culture — wild yeasts and lactic acid bacteria sustained in a flour-and-water slurry. They consume the sugars and starches in flour. As they multiply, they produce carbon dioxide (which makes the starter rise) and organic acids (which give sourdough its flavor). Eventually they exhaust the food supply and become sluggish. Feeding replenishes that supply. The existing microbes are the seed population that colonizes the fresh mixture.

Why ratio matters more than people think

Three variables change with ratio:

Inoculation percentage. In a 1:1:1 feed, existing microbes make up one-third of the mixture. In 1:5:5, they are one-eleventh. More dilution means a smaller starting population relative to available food, which means slower initial activity.

Time to peak. A 1:1:1 feed at 72°F peaks in roughly 4–6 hours. A 1:5:5 feed at the same temperature takes 10–14 hours. The starter feeding calculator estimates peak time based on ratio and temperature.

Sourness. Frequent feedings at small ratios limit acid accumulation, producing a milder starter. Larger ratios with longer intervals allow more acid to build, intensifying sourness.

Common ratios and when to use each

1:1:1 — quick feeding for active bakers or rebuilding a weak starter. Peaks in 4–6 hours at 72°F. Limited souring. Use when you need starter ready fast.

1:2:2 — the standard home maintenance ratio. Peaks in 6–8 hours. Good balance of flavor and activity. Works well for once-daily feeding at room temperature.

1:3:3 — peaks in 8–10 hours. Useful if you want to feed once daily but your schedule needs a bit more lead time before the next feed.

1:5:5 — large feeding for flavor development and overnight schedules. Peaks in 10–14 hours at 72°F. More time for acid to develop means a more complex, tangier result. This is the ratio most bakers use for a pre-bake levain build.

Refrigerator maintenance — activity slows 10× or more in the fridge. A 1:5:5 starter stored at 38–40°F can go 7–14 days between feedings. Take it out, give it two room-temperature feeds over 12–18 hours, and it is ready to bake with.

Reading your starter’s signals

A healthy starter after feeding shows: visible 2–3× rise within the expected timeframe, a domed top at peak, small bubbles distributed throughout (not just on top), a clean slightly acidic smell, and a stretchy web-like interior when you pull it with a spoon.

A starter that needs adjustment shows: sluggish rise (weak culture or cold kitchen), strong sour smell before reaching peak volume (acid building faster than yeast), or collapsed surface with dark liquid on top (“hooch” — the starter has exhausted its food and needs a bigger ratio or more frequent feeding).

Feeding schedule examples

Daily baker: 1:2:2 twice daily, morning and evening. Starter stays at room temperature and is always near peak for spontaneous baking decisions.

Weekend baker: Store in fridge during the week. Friday evening, remove and feed 1:3:3. Saturday morning, feed again at 1:2:2. Saturday afternoon, starter peaks and is ready to use.

Infrequent baker (every 2–3 weeks): Store in fridge after last use. Two days before baking, remove and give two consecutive feeds at 1:5:5 over 12–18 hours each. The timeline generator can help plan the schedule around your target bake time.

What to do with discard

Discard is starter removed before feeding to maintain a manageable quantity. It is perfectly edible and works in any recipe where rise is not the main goal: pancakes and waffles (50g discard adds tang to the batter), crackers, pizza dough, flatbreads, and sourdough English muffins. Store discard in a jar in the fridge for up to a week and use it as you accumulate enough.

Common feeding mistakes

Not weighing. “A cup of flour” weighs anywhere from 110g to 150g depending on how you scoop. Ratios only work with a scale. A $15 kitchen scale pays for itself in consistency within a week.

Mixed hydrations. Feeding a 100% hydration starter with a 75% hydration mixture gives you something in between. Stay consistent with your target hydration, or the starter’s behavior will be unpredictable.

Too-frequent small feeds. Feeding 1:1:1 every 4 hours keeps the starter active but does not allow enough time for flavor-producing acid to develop. The bread will be mild to the point of blandness.

Not feeding enough before baking. A starter that has been in the fridge for a week needs at least two room-temperature feeds to rebuild strength. One feed is often not enough — the yeast population has declined and needs time to recover.

Once it is working, it is working

Well-maintained starters are essentially immortal. Some commercial bakeries have kept the same starter alive for over a century. Once your feeding schedule and ratio produce consistent, predictable results, stop adjusting. Consistency in feeding produces consistency in bread.