Why Isn't My Sourdough Starter Rising? A Troubleshooting Guide
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A starter that won't rise is the single most common reason people give up on sourdough. Almost always, it isn't dead. It's cold, hungry, or being judged too early.
Here are the causes in the order worth checking, starting with the one that's usually the answer.
1. It's too cold — and this is the answer about 70% of the time
Wild yeast is slow below roughly 21°C and barely moves below 18°C. A kitchen that feels comfortable to you can easily be 18–19°C, especially in a German winter or a tiled kitchen with a cold floor.
The fix costs nothing. Put the jar somewhere consistently warm: inside the oven with only the light on, on top of the fridge, in an airing cupboard, or in a cool bag with a jar of warm water beside it. Aim for 24–26°C. Most "dead" starters revive within two feeds of being moved somewhere warm.
A cheap thermometer is worth more than any other piece of sourdough equipment at this stage, because temperature is the variable nobody can feel accurately.
2. You're looking at the wrong window
A healthy young starter can peak and fall back within four hours in a warm kitchen. If you feed at 8am and check at 8pm, you've missed the rise entirely and you're looking at a flat, collapsed surface — which looks exactly like failure.
Two ways to catch it:
- Put an elastic band or a marker line on the jar at feeding level, so you can see where it got to, not just where it is.
- Check at 4, 6 and 8 hours rather than once a day.
If it doubled and fell back, your starter is fine. It's fast, not dead.
3. It's day three to five, and nothing is supposed to happen
New starters have a reliable pattern that catches everybody out: enthusiastic bubbling on day two, then a dead stretch from around day three to day five, then real activity from day six or seven.
That first burst of day-two activity isn't yeast at all — it's bacteria that die off once the mixture acidifies. The lull is the changeover. It is not failure, and almost everybody who quits, quits here.
Keep feeding on schedule and wait. There's more on the whole routine in our guide to caring for a sourdough starter.
4. You're underfeeding it
If you're adding a spoonful of flour to a large jar of old starter, the yeast is living in its own acidic waste and can't get going. Acidity suppresses yeast activity long before it kills anything.
The fix: throw most of it away and feed at a proper ratio. Keep 20g of starter, add 20g flour and 20g water — a 1:1:1 feed. If it's still sluggish, go to 1:2:2 or even 1:5:5, which dilutes the acid further and gives the yeast a clean run.
Feeling wasteful about the discard? Our guide on what to do with sourdough discard covers crackers and pancakes — and, more usefully, how to keep a small enough starter that discard nearly disappears.
5. Your water or your flour
Heavily chlorinated tap water can slow a starter down. It's rarely the main cause, but if you've fixed everything else, leave water out uncovered overnight or use filtered.
Flour matters more. Bleached white flour has less wild yeast on it and less of the mineral content that fermentation needs. If your starter is stubborn, switch to wholemeal or rye for a few feeds — rye in particular tends to wake up a sluggish starter within a day or two, because it carries more of everything the culture wants.
What a dead starter actually looks like
Very few starters die. The ones that have:
- Fuzzy mould — pink, orange, green, black, anything fluffy. Bin it and start again. Don't scrape it off.
- A pink or orange tinge through the mixture, not just on top.
- A smell that isn't sour — rotting, cheesy in a bad way, or like nail polish that doesn't clear after a feed.
Dark liquid on top is hooch. It means hungry, not dead. Pour it off or stir it in and feed.
The 20-minute rescue plan
If you want one sequence to follow:
- Discard down to 20g.
- Feed 20g wholemeal or rye flour and 20g water at about 30°C.
- Mark the level on the jar.
- Put it somewhere 24–26°C.
- Repeat every 12 hours for three days without judging it in between.
If there's no movement after three days of that, then start over — but you'll rarely need to.
While you wait
Standing over a jar for a week is a rite of passage, and it's usually the point at which people start writing things down. Recording feed times, kitchen temperature and what happened turns guessing into diagnosis — our notebooks exist for exactly that, and how to keep a sourdough journal covers what's worth recording.
Questions we get asked
How long does a new sourdough starter take?
Seven to fourteen days to become reliably active, with a dead-looking lull around days three to five that is completely normal. Warmth is the biggest factor — a cold kitchen can double the timeline.
Can I revive a starter that's been in the fridge for months?
Usually yes. Discard down to a spoonful, feed 1:1:1, keep it warm, and repeat every 12 hours. Three to five feeds is typical. Unless it's mouldy, assume it's recoverable.
What temperature should a starter be kept at?
24–26°C for active fermentation. Below 21°C it slows noticeably; below 18°C it nearly stops. The oven with the light on is the standard household solution.
Should I use rye flour?
It's the best rescue flour — more wild yeast, more minerals, faster response. Use it for a few feeds to get things moving, then return to whatever flour you normally bake with.