Sourdough Clock

Sourdough Starter Not Rising? Check Temperature, Ratio, Flour

By Tam Vu · Updated

On this page
  1. 1. Check the starter's temperature
  2. 2. Check the feeding ratio
  3. 3. Check the flour and water amounts
  4. Track one change at a time
  5. Source

If a sourdough starter is not rising after a feed, check three things before changing the whole routine: the starter's temperature, the feeding ratio, and the flour. Change one variable at a time and mark the level after feeding so you can compare what happens.

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1. Check the starter's temperature

Temperature can change how quickly sourdough organisms grow. In the 1998 study by Gänzle, Ehmann and Hammes, the tested sourdough yeast grew fastest at about 27 °C (81 °F), while the tested sourdough bacterium grew fastest at 32–33 °C (90–91 °F). The study describes 20–28 °C (68–82 °F) as a usual sourdough fermentation range.

If the starter is below about 20 °C (68 °F), expect slower activity; a cool kitchen does not necessarily mean the starter has failed. The published temperature model is based on specific strains and lab measurements, so it helps explain direction and relative speed, not an exact peak time for every home starter. Use the temperature guide and schedule calculator as planning aids; the calculator covers 18–30 °C.

2. Check the feeding ratio

Write down the feed by weight. In a 1:1:1 ratio, use equal weights of starter, flour and water. In a 1:2:2 ratio, use twice the starter's weight in flour and twice its weight in water. How long your starter takes to peak at a given ratio is something to measure in your own kitchen. If you changed the ratio, return to a feed you know and observe that one before making another change. The starter feeding calculator can convert a target starter amount into ingredient weights.

3. Check the flour and water amounts

If you switched flour, compare with a feed using the flour that previously worked. Keep the ratio and water amount consistent while you observe the result. When you change both flour and hydration at once, it is harder to tell which change affected the starter's texture and rise. Use the hydration calculator to check the flour and water balance, including the water and flour already in the starter.

Track one change at a time

After feeding, mark the starter's starting level on a straight-sided container and note the time, temperature, ratio and flour. Compare it with a previous feed made under similar conditions. If the starter is active but the rise is hard to see, the mark makes the change in level easier to compare.

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