Sourdough · Fix it

Why is my starter not doubling

By Benjie Evans · Last updated 12 October 2026

A starter that won't double is usually underfed relative to its size, kept somewhere too cold, or simply young and still building strength. Feed it more generously, move it somewhere warmer, and give a young starter another week or two of consistent feeding before judging it.

What it's telling you

Likely causes, most likely first

1

It's too cold

How to tell: It rises a little and slowly, and your kitchen is under about 20°C. Below that a starter can take twice as long to peak, so it may double eventually, just not when you're watching.

What to change: Keep it at 24 to 26°C: a warm cupboard, the top of the fridge, or the oven with only the light on (check with a thermometer that it doesn't climb past 30°C). Warmer water at feeding helps too.
Work out your feed amounts in the starter calculator
2

It's underfed for its size

How to tell: A big jar of old starter gets a small feed and only rises a little, or it smells sharp like nail varnish between feeds.

What to change: Discard down to about 25g and feed 1:1:1 by weight (25g starter, 25g flour, 25g water), or 1:2:2 if it peaks too fast. More fresh food for the culture, a clearer rise.
3

It's still young

How to tell: It's under two or three weeks old, or it bubbled hard in the first few days and then went quiet. That early burst usually isn't the yeast you want.

What to change: Keep feeding on schedule. Most starters settle and double reliably somewhere in weeks two to three.
4

The flour is very refined

How to tell: You only feed plain white flour.

What to change: Swap 20 to 50% of each feed for wholemeal or rye. More nutrients, more activity.
5

It is rising, the jar just hides it

How to tell: There's no band or mark on the jar, and you only look now and then.

What to change: Put a rubber band at the level after feeding and check at 4, 8 and 12 hours.

Diagnose it

Which one matches your dough

Symptom variant, likely cause, fix and prevention
Symptom	Likely cause	Fix	Prevention
Rises a little but never doubles	Underfed relative to its current size	Increase the flour and water ratio at each feed	Feed generously and consistently, roughly equal parts by weight
Was doubling, now sluggish	Kitchen has got colder, or feeding has become inconsistent	Move somewhere warmer, resume regular feeds	Keep feeding on a consistent schedule
Brand new starter, no activity yet	Still building its microbial population	Keep feeding daily, give it another week or two	Expect one to three weeks before reliable doubling
Doubles slowly but smells strongly of acetone or nail varnish	Starving between feeds, needs feeding more often	Feed more frequently, potentially twice a day	Match feeding frequency to how fast it's consuming food

Stop it happening again

Fix the cause, not just the bake

Getting your starter's feeding ratio and timing right is the foundation of consistent doubling. Our sourdough starter troubleshooting guide walks through six more starter problems in detail, and the Starter Calculator below helps you size your feeds and inoculation percentage correctly for whatever you're baking.

Size your starter feeds in the Starter Calculator

Sourdough Rescue Handbook £12.00

Still stuck?

Email me your feeding ratio, how often you feed, and your kitchen temperature. I'll tell you what I'd try next.

Email Benjie

Common questions

FAQ

Why is my sourdough starter not doubling?

A starter that won't double is usually underfed relative to its size, kept somewhere too cold, or simply young and still building strength.

How long should it take for a new starter to double?

Most new starters take one to three weeks of consistent daily feeding before they reliably double within 4 to 8 hours, though this varies with kitchen temperature.

What feeding ratio helps a sluggish starter?

Equal parts starter, flour and water by weight is a reliable starting point. If it's still sluggish, feeding a little more generously or more frequently often helps.

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