Why is my sourdough starter not doubling?
A starter that will not double is usually too cold, fed on the wrong ratio, or out of balance from infrequent feedings. Keep it at 76–80°F, feed at least 1:5:5 with 100% fresh milled or a 50/50 fresh milled/bread flour blend, and feed twice daily for several days to rebuild strength.
Key Takeaways
- Temperature matters more than any other variable — aim for 76–80°F.
- Fresh milled flour feeds a starter aggressively because of its live enzymes.
- A 1:5:5 feed gives yeast room to grow without exhausting food too fast.
- Twice-daily feeds for 3–5 days will rehabilitate most sluggish starters.
- A starter that smells acetone or vinegar is hungry, not dead.
Problem
A sourdough starter feeds normally but fails to reliably double in volume between feedings.
Symptoms
- Rises 30–50% then stalls.
- Takes 12+ hours to peak.
- Small bubbles only, no domed top.
- Sharp, solvent-like smell.
- Liquid (hooch) forms quickly on top.
Likely causes
Cool kitchen temperature
Below 72°F, starter activity slows dramatically and may never peak between feedings.
Underfeeding
A 1:1:1 feed exhausts food in hours, leaving the starter starved and acidic by peak time.
Chlorinated tap water
Chlorine and chloramine suppress wild yeast and lactobacilli.
Weak flour blend
100% white flour can lack the minerals and enzymes a starter needs; fresh milled supercharges it.
Infrequent feeding
Once-a-day feeding at room temperature leaves the starter starving for half the day.
Solutions
- 1
Move the starter to 76–80°F
Oven with the light on, on top of the fridge, or a seedling mat under a towel.
- 2
Switch to a 1:5:5 feeding ratio
For example 20g starter + 100g flour + 100g water; gives yeast room to multiply.
- 3
Use fresh milled flour
100% fresh milled hard wheat or a 50/50 blend with bread flour feeds the starter the enzymes it craves.
- 4
Feed twice a day for 3–5 days
Morning and night until the starter doubles reliably within 4–6 hours.
- 5
Use filtered or dechlorinated water
Let tap water sit uncovered for an hour or use spring/filtered water.
- 6
Discard down before each feed
Lower starter mass means a higher fresh-food ratio without scaling up the jar.
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