Why isn't my sourdough starter rising?

A sourdough starter that won’t rise is almost always one of four things: it is still young and building strength, your kitchen is too cold, the feed has too much old starter and not enough fresh flour, or the flour is low in nutrients. The good news is that all four are easy to fix, and a stalled starter is rarely dead.

Give a young starter time

A brand new starter often takes 10 to 14 days before it rises reliably. In the first week it may bubble, smell sharp, then go quiet. That is normal. Keep feeding it once or twice a day and watch for a consistent rise and fall between feeds before you judge it.

Warm it up

Temperature is the biggest lever on fermentation. A starter at 18 C ferments far slower than one at 26 C. Move it somewhere warm: on top of the fridge, near the oven, or in the oven with just the light on. Aim for roughly 24 to 27 C.

Feed it more, with better flour

If you keep a lot of starter and add only a little flour, there is not enough fresh food to drive a strong rise. Try a larger feed ratio such as 1:5:5 (one part starter, five parts flour, five parts water). Adding a spoonful of whole wheat or rye flour helps too, since whole grains ferment faster and feed the culture well.

What a healthy rise looks like

After a feed, a strong starter rises, domes, and then falls back. The top of that rise is the peak, and it is the best time to bake. If you see bubbles throughout and a springy, mousse-like texture, it is working.

When to worry

Throw a starter out only if you see fuzzy or colored mold, or it smells truly foul. A hungry starter that smells sharp, like acetone, is not spoiled. It just wants a feed.