Building and Maintaining a Sourdough Starter
A sourdough starter isn't magic, though it can feel that way the first time you watch flour and water come alive with activity. It's a symbiotic colony of wild yeast and lactic acid bacteria that you cultivate from what's already in your flour, your water, and your kitchen. Once established, it becomes the engine for every loaf you bake.
What you're actually building
A sourdough starter is a living culture that ferments. It requires feeding (flour and water), clean conditions, and patience. The first week is the loudest—you'll see bubbles, smell fermentation, watch the mixture rise and fall. After that, it settles into a rhythm. Don't overthink it. Flour, water, time, and consistency are all you need.
- A clean glass jar (1-quart or larger)
- A kitchen scale (not required, but makes feeding precise)
- A spoon for stirring
- Cheesecloth or a coffee filter (optional, for covering the jar)
What goes in.
- equal parts by weightall-purpose or bread flour
- equal parts by weightfiltered or dechlorinated water (room temperature)
Feeding the starter (and knowing when it's ready)
Feeding means removing a portion of the existing culture and adding fresh flour and water. You're not replacing the whole jar—you're maintaining the colony while keeping it hungry enough to stay active. A starter is ready to bake with when it reliably doubles in volume within 4–8 hours of feeding and shows visible bubbles throughout.
The method.
Mix your first culture
In a clean jar, combine 50 grams of flour and 50 grams of water. Stir until everything is wet—there should be no dry flour left. The mixture will be thick and shaggy. Cover loosely with cheesecloth or a coffee filter (you want air exchange, not contamination). Leave it on your counter at room temperature (68–72°F is ideal, but 65–75°F works).
Wait and observe
For the first 24–48 hours, nothing may happen. This is normal. Around day 2 or 3, you'll see some bubbles and possibly a smell—sour, yeasty, or slightly alcoholic. This is the wild yeast and bacteria waking up. Don't panic if it smells odd. An actively fermenting culture doesn't smell rotten; it smells alive.
Begin daily feedings (days 3–7)
Once you see any activity, start feeding once daily. Remove about half the starter (roughly 50 grams, or a heaping tablespoon) and discard it. Add 50 grams of fresh flour and 50 grams of fresh water to what remains. Stir well. The starter will smell strong, rise and fall unpredictably, and may develop a dark liquid on top (called hooch—it's alcohol from yeast fermentation; stir it in or pour it off, both are fine). Keep feeding at the same time each day.
Watch for predictability (days 5–7)
By day 5 or 6, the starter should begin doubling within 4–8 hours of feeding. You'll see a clear rise and a dome of bubbles. It may fall back down before your next feeding—that's okay. The signal that it's ready is consistency: if it doubles reliably two days in a row, you can bake with it. If it's still erratic, feed it for another 2–3 days.
Transition to maintenance feeding
Once your starter is strong and predictable, you can refrigerate it and feed it once a week instead of daily. Remove half the starter, add equal parts flour and water (50 grams each is a standard portion), stir, and refrigerate. The cold slows fermentation dramatically. When you're ready to bake, remove the starter from the fridge, feed it, and let it come to room temperature and rise fully—usually 4–12 hours depending on temperature. Only use it for baking once it's peaked (risen fully and showing its characteristic dome).
Other turns to take.
Whole wheat or rye starter
Substitute 25–50% of the all-purpose flour with whole wheat or rye flour. These ferment slightly faster due to higher enzyme activity, so you may see activity sooner and need to feed more frequently. The process is otherwise identical.
Higher hydration starter
Use more water relative to flour—for example, 50 grams flour to 75 grams water—to create a thinner, pourable culture. This ferments faster and is easier to incorporate into doughs, but requires the same feeding discipline.
Dried starter backup
Once your starter is established, you can dry a portion on parchment paper and store it in an airtight container. To revive, crumble the dried starter into flour and water and feed it as normal. It may take an extra feeding or two to wake up fully.
When it doesn't go to plan.
Water matters. If your tap water is heavily chlorinated, filter it or let it sit uncovered overnight to allow chlorine to evaporate. Chlorine can inhibit fermentation.
Temperature controls speed. A warmer kitchen (72–75°F) will move things faster. A cooler one (65–68°F) will slow everything down. Adjust feeding frequency accordingly—feed more often in warmth, less often in cold.
The 'float test' tells you when your starter is ready to bake: take a small spoonful, drop it in water. If it floats, the starter is mature enough (full of gas). If it sinks, wait longer.
Hooch (the dark liquid that accumulates) is fermented alcohol from yeast. You can stir it back in for more sour flavor or pour it off for a milder result.
Don't use metal utensils or containers long-term. Glass or ceramic is best; metal can react with the acidic starter over time.
If your starter develops pink or orange streaks, mold, or a nail-polish-remover smell that persists, it's contaminated. Discard it and start over.
You don't need fancy ingredients. Standard all-purpose flour and filtered water are enough. Whole wheat or rye can speed things up, but aren't necessary.
Consistency in feeding time helps your starter anticipate meals. If you always feed at 8 a.m., it will learn to peak around noon.
The ones that keep coming up.
How do I know if my starter is dead?
A dead starter won't show any activity—no bubbles, no rise, no smell—after a week of daily feedings. It's also dead if it develops a fuzzy mold (white, green, or pink). A sour or alcoholic smell is not death; that's fermentation. If in doubt, feed it one more time and wait 24 hours. A living starter will show signs within that window.
Can I speed up the process?
Slightly. Warmer temperatures (75–80°F) will accelerate fermentation. Using a small amount of whole wheat or rye flour can also jumpstart activity because those grains have more wild microbes. But don't try to rush the first week. The culture needs time to establish dominance. Speeding it artificially often leads to unpredictable starters.
What if I forget to feed my starter?
A refrigerated starter can survive 2–3 weeks without feeding, though you may see a dark liquid on top (hooch) that needs to be stirred back in. A room-temperature starter will die after about a week of neglect. If you've missed a few feedings, feed it once and observe. If it shows activity within 24 hours, it's alive. If nothing happens after two feedings, it's gone.
Do I need a scale to maintain a starter?
A scale makes feeding precise and predictable, which helps troubleshooting. But you can use ratios by sight: remove about half the mixture with a spoon, then add roughly equal volumes of flour and water. It won't be exact, but it works. A starter is forgiving if you're consistent, even if that consistency is approximate.
Why does my starter smell like nail polish remover or acetone?
That's normal. It's the smell of fermenting yeast—the byproduct is ethanol and acetaldehyde. It's not pleasant, but it's not harmful. Stir the starter well and the smell usually fades. If the smell is extremely strong and persists for days even after stirring and feeding, something may be off.
Can I bake with a cold starter straight from the fridge?
Not effectively. A cold starter ferments very slowly. You need to remove it from the fridge, feed it, and let it come to room temperature while it rises. Only use it once it has peaked—usually 4–12 hours later, depending on kitchen temperature. Baking with a cold, unfed starter produces a dense loaf.
What's the difference between a 'stiff' and 'liquid' starter?
A stiff starter has more flour than water (like thick dough). A liquid starter has more water than flour (like thick batter). Both work; it's preference. Stiff starters ferment slower but are easier to handle. Liquid starters ferment faster and mix more easily into doughs. The one you build depends on your feeding ratios.