How to Feed Sourdough Starter: Ratios, Timing, Rescue

In my grandmother’s kitchen the rye starter sat in a crock by the stove, and feeding it was as ordinary as putting the coffee on. Learning how to feed a sourdough starter is the one habit that keeps that wild culture alive, and it is simpler than the internet makes it look: you pour most of it away, stir in fresh flour and water, and wait. Keep a rhythm your kitchen can actually hold to, and the same jar will raise bread for decades. Here is the ratio, the schedule for both the counter and the fridge, how to tell when it is ready to bake, and how to revive a neglected starter.

Why do you have to feed a sourdough starter?

A starter is a living colony of wild yeast and lactic acid bacteria, and like anything alive, it has to eat. Feeding does two jobs: the fresh flour restocks the sugars the microbes live on, and discarding first keeps the jar from filling up and turning too acidic for the yeast to stay strong. Skip feedings and the culture runs out of food, floods itself with acid, and goes sluggish. The wild fermentation that makes sourdough tangy is exactly what you tend when you feed, and the yeast-and-bacteria balance that the research indexed at the National Library of Medicine describes is what a steady rhythm keeps healthy. If you have not built a starter yet, our how to make a sourdough starter guide covers the 7-day build first.

How do you feed a sourdough starter?

The everyday feed is three things in equal weights: your existing starter, fresh flour, and water. You keep a small amount of starter, stir the fresh flour and water into it, and let it rise. Weighing on a kitchen scale beats measuring by volume here, because a starter’s texture makes cups wildly inconsistent.

1. Discard down to about 50 g. Pour off all but roughly a quarter cup of starter. This is not waste, so keep the discard in a jar in the fridge to bake with.
2. Add equal weights of flour and water. Stir 50 g fresh flour and 50 g room-temperature water into the 50 g you kept.
3. Mix until smooth, with no dry flour left, and scrape down the sides of the jar so nothing crusts.
4. Mark the level with a rubber band or a marker, cover loosely (never airtight), and leave it at warm room temperature.
5. Watch for the peak. It is fed and working when it rises to roughly double, domed and bubbly, in 4 to 12 hours. Bake at that peak, or feed it again to keep it going.

A good whole rye flour is my desert-island feed because its bran wakes a starter up fastest, but any unbleached flour works. Avoid bleached flour, where the chlorine treatment knocks back the very microbes you are feeding.

What is the right feeding ratio?

One part starter to one part flour to one part water, by weight, is the everyday default. The ratio simply controls how long the starter takes to peak and how sour it gets: feed it more flour and water per part of starter and it takes longer, stays milder, and needs feeding less often. In a warm kitchen or when you want to stretch to one feed a day, lean on the bigger ratios.

How often should you feed a sourdough starter?

It depends entirely on where you keep it, and both approaches are valid. A starter on the counter is in fast, active mode and wants feeding once or twice a day; a starter in the fridge is in slow storage mode and is happy with about one feed a week. Match the rhythm to how often you bake rather than to some rule.

For weekend bakers the fridge is the sane choice: feed once midweek, then give it a couple of feeds the day before baking. Our best flour for a sourdough starter guide covers which flour to use at each stage.

When is a fed sourdough starter ready to bake?

The doubling test is the one that matters: a starter that reliably rises to double within 4 to 12 hours of a feed, domed and webbed with bubbles, has the strength to raise a loaf. Mark the jar at feeding time and watch the clock, not your hopes. The float test (a spoonful floats when gassy) is a fair spot-check, but it gives false negatives on heavy rye starters, so do not let a sinking spoonful overrule two clean doublings. Your nose is the third gauge: a ready starter smells tangy and faintly fruity, not like nail polish or old socks.

Why isn’t my starter rising after feeding?

Nine times out of ten the culprit is temperature or timing, not a dead starter. Here are the usual causes, and the fixes I have learned tending jars through cold Nordic winters.

• The kitchen is too cold. Below about 65°F a starter crawls. Move it somewhere warm, near the oven light or on top of the fridge, and give it time.
• It is underfed for the warmth. In a hot kitchen a 1:1:1 feed can peak and collapse before you look. Feed it more often, or switch to a 1:5:5 ratio so it lasts.
• It is young or was fed erratically. A new or neglected starter needs a few days of feeding at the same time each day to find its rhythm. Consistency fixes more problems than any single trick.
• You are judging it too soon or too late. Peak might be at hour 5 in summer and hour 10 in winter. Watch the rubber-band line, not the clock alone.

A few 100% rye feeds are the standard rescue for a genuinely sluggish culture, and activity usually doubles within 48 hours. Our rye flour guide explains why rye’s bran-rich flour earns that job.

Do you have to discard every time you feed?

For a starter you are keeping and baking with, yes, discarding before each feed is what keeps its volume and acidity in check so the yeast stays vigorous. The way to make peace with it is to keep a small starter (as little as 20 to 50 g between feeds) so there is little to throw, and to treat the discard as an ingredient rather than trash. It is essentially unfermented bread batter, and our sourdough discard recipes collection turns it into pancakes, crackers, bagels, and cinnamon rolls. And while your starter finds its feet over its first week, dinner still happens, so a rice-cooker batch of perfectly cooked quinoa asks even less of you than the jar does.

Where to go from here

Once feeding is second nature, the starter is ready to work. Our whole grain sourdough bread is the natural first loaf, and the Real Bread Campaign’s sourdough guidance is a good independent reference for what real sourdough fermentation involves. If you feed a heritage flour, the rye and spelt grain pages cover the two that give a starter the most character.