How to Feed Sourdough Starter
Feeding a sourdough starter is just discarding most of it and stirring in fresh flour and water, but getting the ratio, timing, and consistency wrong is why so many starters go flat or grow mold instead of bubbling.
Steps
- 1Discard all but about 20-30g of the existing starter, scraping the jar down to a thin layer.
- 2Add 100g of flour (a mix of all-purpose and whole wheat or rye works well) directly to the remaining starter.
- 3Add 100g of room-temperature water (a 1:1 flour-to-water ratio by weight).
- 4Stir vigorously with a fork or spatula until no dry flour streaks remain and the mixture looks like thick pancake batter.
- 5Scrape down the sides of the jar so nothing dries out and crusts over.
- 6Loosely cover the jar with a lid or cloth (don't seal it airtight) and set it somewhere between 70-78°F (21-26°C).
- 7Let it sit for 4-12 hours, until it has roughly doubled in volume and looks domed or bubbly on top before feeding again.
Common mistakes
- Skipping the discard: feeding the whole jar every time dilutes the ratio and leaves the colony too thin to build strength.
- Using cold water straight from the fridge: it slows fermentation and can make the starter sluggish for hours longer than expected.
- Sealing the jar completely airtight: trapped gas can build pressure or suffocate the culture; a loose lid or cloth cover works better.
- Feeding on a rigid clock instead of watching activity: a starter in a cool kitchen needs longer between feeds than one in a warm kitchen.
- Ignoring a thick gray or brown liquid on top (hooch) for too long: it signals the starter is hungry and needs feeding sooner, not less often.
Equipment
- Glass or plastic jar with a loose-fitting lid
- Kitchen scale
- Fork or spatula for stirring
FAQ
How often should I feed my sourdough starter?
If it lives at room temperature, feed it once or twice a day. If it's stored in the fridge, feeding once a week is enough to keep it alive.
What does it mean if my starter has a layer of dark liquid on top?
That liquid is hooch, alcohol produced when the starter runs out of food. Pour it off (or stir it in for a more sour flavor) and feed the starter right away.
Can I use only whole wheat or only all-purpose flour?
Yes, either works alone, but whole wheat and rye ferment faster because they carry more wild yeast and bacteria, so an all-purpose-only starter may rise more slowly.
How do I know my starter is ready to bake with after feeding?
Do the float test: drop a small spoonful in water. If it floats, the starter has enough gas trapped in its structure to leaven bread.
Why isn't my starter doubling after feeding?
It's usually temperature or a discard ratio that's too large for a weak culture. Move it somewhere warmer, closer to 75°F, and keep more of the existing starter (closer to 50g) at the next feed.
Need exact temperatures or timing? Check our Time & Temperature Guide →