Dough Dough Guides
The question I get more than any other is a worried one: "Is my starter actually working?" Nine times out of ten the answer is yes — it's just doing its thing more quietly, or more slowly, than expected. Here's how to tell a healthy, active culture from one that genuinely needs help, and how to fix the handful of things that really do go wrong.
By Richard — I developed our shelf-stable starter myself and I keep cultures going every day for our Airbnb baking, so I've seen every wobble a starter can throw at you.
What an active, healthy starter looks like
Before you worry, check it against the real signs of life. A happy starter, at its peak a few hours after feeding:
- Roughly doubles in size and forms a domed top.
- Is full of bubbles, big and small, all the way through.
- Smells pleasantly sour and yeasty — tangy, a little like beer or yoghurt.
- Passes the float test at its peak.
The float test
Drop a teaspoon of starter into a glass of water. If it floats, it's full of gas and ready to bake with. If it sinks, give it more time or another feed. It's the quickest health check there is.
First thing to check: temperature
This is the answer far more often than people expect. Wild yeast is most active around 24–26°C. Below that it slows right down, and a cold kitchen can make a perfectly healthy starter look sluggish. My own kitchen sits at 22–23°C, so I know mine runs a touch slower and I give it time, or pop it somewhere warmer — near (not on) the oven, in a turned-off oven with the light on, or in an airing cupboard.
Symptom by symptom
"It's barely bubbling after a couple of hours"
Almost always just too cool. Move it somewhere warmer and give it more time — activity ramps up fast once it warms through. A barely-bubbling starter is rarely a dead one.
"No rise at all, even after feeding"
Three things to rule out: it's too cold (warm it up), the water was too hot and shocked it (start a fresh feed with lukewarm water), or it simply needs a couple more feeds to wake fully. Discard down to a small amount and feed it 1:1:1 (equal weights starter, flour, water) once or twice a day for 2–3 days — persistence almost always brings it back.
"There's a grey or brown liquid on top"
That's hooch, and it's harmless — just a sign the starter is hungry and due a feed. Stir it back in for a slightly tangier result, or pour it off, then feed as normal.
"It smells like nail polish, acetone or sharp vinegar"
An over-hungry starter. It has eaten everything and gone acidic. Feed it more often, or with a bigger ratio of flour and water (say 1:5:5), so it has more to live on between feeds.
"It smells sweet and doughy and won't rise"
Usually underfed or too cold. Feed it more generously and keep it warmer. A sweet, flat smell means the yeast isn't getting going.
"It rises beautifully, then collapses quickly"
Nothing's wrong — it simply peaked and ran out of food. Either use it sooner after feeding (catch it at the top of its rise) or feed a bigger ratio so it takes longer to peak and holds there.
"It rises, but only halfway — it never doubles"
A weak yeast population rather than a sick one. Feed it twice a day at room temperature for five to seven days with about 20% wholegrain flour blended into the feed — the bran carries far more wild yeast than white flour does, and the count builds. Worth saying: plenty of perfectly good starters top out around 50–75% rather than a clean double, and they bake fine.
"It's watery and thin" or "it's thick, dry and cracked on top"
Both are consistency, not health. Thin means too much water in the feeds — drop back to equal weights of flour and water. Thick and cracked means too little water, or the jar drying out uncovered: add a little more water next feed and cover it loosely with a lid resting on top or a cloth. Neither affects whether the starter works.
"It's separated into layers after the fridge"
Completely normal after a long cold stint — the water simply settles out from the flour. Stir it back together, then feed as usual.
"It smells of vinegar"
Slightly underfed, with more acetic acid than usual. Feed more often, every eight to twelve hours, and use slightly warmer water — that shifts the balance back towards the softer lactic acids and the smell mellows.
"It smells sweet and fruity"
Usually a very young starter, or one that has just been fed. Nothing to fix. The smell gets more complex as the culture matures.
"It has no smell at all"
Cold, or very slow. A genuinely active starter always smells of something. Warm it up, feed it with a wholegrain blend, and give it 24 hours before judging.
"It smells of alcohol just after a refresh"
Yeast activity running ahead of the bacteria. Feed a stiffer mix — a little less water — which favours acid production and brings the two back into balance.
"It smells fine but never doubles"
Healthy bacteria, not enough yeast. Feed with around 30% wholegrain rye twice a day for a week. Rye is the fastest way to lift a yeast count.
"Lots of small bubbles, but no rise"
The gas is being made and then escaping — the gluten network is too weak to hold it. Switch from plain flour to a strong bread flour; the higher protein traps the gas instead of letting it out.
"It doubles in two hours, then dies back"
Too warm, and it has simply eaten everything very fast. Feed a much bigger ratio (1:5:5, or 1:10:10 in real heat) so the food lasts longer, or move it somewhere cooler. A fast starter is a strong starter — you just need to catch it earlier.
"It used to work and suddenly doesn't"
Something in its environment changed, and it is nearly always one of three things: a new brand or bag of flour, a colder or warmer spot, or a change in your tap water. Go back to basics for a week — same flour, 22–25°C, twice-daily 1:1:1 feeds — and it will re-establish.
"I bought a shelf-stable starter and it won't wake up"
Check the water temperature first: too cold and it stays dormant, too hot and you damage it. Lukewarm, around body temperature, and follow the supplier's ratio exactly rather than improvising. If it is ours and it has not come to life, the 2-hour activation guarantee covers it — we will replace it, no questions asked.
"I forgot to feed it for weeks"
Don't panic — starters are tougher than they look. As long as there's no mould or pink, it's almost certainly revivable. Discard down to a tablespoon, feed 1:1:1, and repeat once or twice a day. Within 2–3 days it should be bubbling and doubling again. Full routine in my feeding & care guide.
How long can you leave it?
The single most common worry, and almost always a smaller problem than it feels. Find the gap and the fix:
| How long since the last feed | What to do |
|---|---|
| A day, at room temperature | Nothing special. Feed as normal, discarding down to about 50g first if the jar is full. |
| Three days to a week, at room temperature | Discard all but 20g. Feed generously — 1:5:5 — with warm water and half wholegrain flour. Two or three daily feeds to bounce back. |
| A fortnight, in the fridge | Entirely normal. Let it sit out for half an hour, discard to 50g, feed 1:1:1. Two room-temperature feeds and it is bake-ready. |
| A couple of months, in the fridge | Same routine, more patience — expect five to seven daily feeds before it doubles reliably. Most starters come back. |
When to actually worry
Only mould or pink/orange streaks. Everything else — slow bubbling, hooch, a sharp smell, a collapse — is normal starter behaviour and completely fixable with food and warmth. And if our starter genuinely never comes to life, that's exactly what the 2-hour activation guarantee is for: we'll replace it, no questions asked.
When the starter is fine but the loaf isn't
Worth checking which problem you actually have. If the jar doubles on schedule, smells right and passes the float test, your starter is not the fault — and feeding it differently will not fix a dense crumb, a flat loaf or a bake that is too sour. Those come from the dough: hydration, bulk timing, shaping and the bake itself. My loaf troubleshooting guide works through those symptom by symptom.
And if your problem genuinely is not on this page, tell us about it. Send a photo and a description and we will diagnose it for you — and add the answer here for the next person who hits the same thing.
No starter yet, or want a fresh, reliable one? Ours is live, and ready to bake in 2 hours — no 7-day wait.
Buy a sourdough starter →Sourdough Starter Troubleshooting — Quick FAQ
Why is my sourdough starter not rising?
Nine times out of ten it's temperature. Wild yeast is most active at 24–26°C. Below 22°C it slows dramatically. Move it somewhere warmer (near, not on, the oven; a turned-off oven with the light on; an airing cupboard) and give it more time. If it's warm and still not rising, feed 1:1:1 (equal weights starter, flour, water) once or twice a day for 2–3 days — persistence almost always brings it back.
My sourdough starter has grey liquid on top — is it dead?
No. That's hooch — harmless alcohol produced when the starter has eaten all its food and is hungry. Stir it back in for a tangier result, or pour it off, then feed as normal.
My sourdough starter smells like nail polish or acetone. What now?
An over-hungry starter. It has fermented everything and gone acidic. Feed it more often, or with a bigger ratio of flour and water (1:5:5 instead of 1:1:1) so it has more food between feeds.
How do I know if my sourdough starter is dead?
Almost never. The only real death signs are pink, orange or red streaks, or fuzzy mould (fluffy white, green or black growth). Everything else — no rise, sharp smell, hooch, collapse — is fixable with warmth and feeding. If you see mould, throw it out and start fresh.
Can I revive a sourdough starter I forgot to feed for weeks?
Yes, almost always. As long as there's no mould or pink streaks, it's revivable. Discard down to a tablespoon, feed 1:1:1, and repeat once or twice a day. Within 2–3 days it should be bubbling and doubling again.
Why does my sourdough starter rise then collapse?
Nothing is wrong — it peaked and ran out of food. Either use it sooner after feeding (catch it at the top of its rise) or feed a bigger ratio (1:3:3 or 1:5:5) so it takes longer to peak and holds there.
My sourdough starter is too runny / too thick — is it OK?
Yes. Consistency is cosmetic, not a health issue. Hydration is personal preference — most bakers keep starters at 100% hydration (equal weights flour and water), but anything from 50%–125% works. Adjust with a little more or less water at the next feed.
What water should I use to feed my sourdough starter?
Filtered or dechlorinated tap water is best. Chlorine in fresh tap water can slow or damage the culture. Leave tap water uncovered for a few hours to let chlorine dissipate, or use a filter. Never use very hot water (over 40°C) — it will start to kill the culture.
How long can a sourdough starter go without being fed?
Longer than you would think. A day at room temperature is nothing. Three to seven days at room temperature needs a hard discard and a generous 1:5:5 feed. A fortnight in the fridge is normal and takes two feeds to recover. Even a couple of months in the fridge is usually survivable — expect five to seven daily feeds before it doubles reliably again.
My starter smells fine but never doubles. What's wrong?
A healthy bacterial population with not enough wild yeast alongside it. Feed with around 30% wholegrain rye flour twice a day for a week; rye carries far more wild yeast than white flour and it lifts the count faster than anything else.
From the book
Every fault on this page is photographed in Your First Sourdough, next to what caused it and what to do about it.
Your First Sourdough — see all three editions ›