Why is my sourdough starter not rising?

A starter that is not rising is nearly always rising slowly, or has already risen and fallen while you were at work. Working through the causes in order of likelihood saves both the starter and a great deal of unnecessary discarding, and the order almost never changes.

Step by step

1. Take the kitchen's actual temperature.Not what it feels like. A UK kitchen worktop in winter is often 15 to 17°C, and starter activity roughly halves for every few degrees below 22°C. This is the cause in most cases, and it is invisible because the starter looks the same as a dead one.
2. Move it somewhere consistently warm and give it three days.Oven with the light on, airing cupboard, on top of the fridge, or in a cool bag with a jar of warm water. 22 to 25°C. Feed once a day and judge it after three days at temperature, not after one.
3. Check you are not simply missing the peak.Put an elastic band round the jar at the level immediately after feeding. A vigorous warm starter can double and collapse in four hours, so checking after twelve hours shows you a flat jar that has already done everything you wanted. The band shows the high-water mark.
4. Look at the feeding ratio.Equal weights of starter, flour and water — 1:1:1 — peaks fast and falls fast. A larger ratio such as 1:5:5 takes far longer to peak but climbs much higher. If your starter is sluggish, a bigger feed of fresh flour with less old starter often wakes it up within two cycles.
5. Change the flour.Switch to wholemeal or rye, or add a spoonful of it to every feed. Wholegrain flour carries more of the organisms and more of the minerals they need. Very low-protein plain flour and heavily bleached flour both give weak results.
6. Rule out the water.Use filtered water or tap water left standing for an hour. In heavily chlorinated areas this is occasionally the whole problem, and it costs nothing to eliminate.
7. Feed twice a day for three days.A starter that has been neglected, kept in the fridge for months, or repeatedly underfed needs a run of consistent feeding to recover. Twice daily at 22 to 25°C for three days is the standard revival, and it works far more often than people expect.
8. Distinguish flat from dead.A flat starter that still smells sour, yeasty or vinegary is alive and slow. A starter with fuzzy growth, or pink, orange or black streaks, is contaminated and must be thrown away and restarted. Those are the only two categories.

Tips

• Bubbles without a rise usually mean the ratio is off, or the mixture is too thin to hold gas. A slightly stiffer starter rises more visibly.
• A tall narrow jar shows a rise far more clearly than a wide one. The same starter looks dead in a bowl and impressive in a jar.
• A starter straight out of the fridge needs two or three feeds at room temperature before it will behave. Do not judge it on the first one.
• The float test is a rough guide, not a verdict — high-hydration starters often sink and still bake well.

Common mistakes

• Concluding it is dead after twelve hours — In a cold kitchen a healthy starter can take fourteen to eighteen hours to peak. The judgement has to be made at a known temperature over several days, not from one disappointing morning.
• Feeding it more often in the hope of waking it up, without warming it — Feeding a cold starter frequently dilutes the culture faster than it can grow, and it gets weaker. Warmth first, then a feeding schedule.

Questions people ask