A sourdough starter that refuses to rise is the single most frustrating problem in home baking. The flour and water look exactly the same as last week, the jar is in the same spot, the feeding schedule has not changed, and yet the dome that used to triple in 6 hours now sits flat and lifeless for a full day. Diagnosing why a starter has stalled is a process of elimination across four variables: temperature, feeding ratio, flour quality, and water chemistry. Most stalled starters revive within three to five days once the right variable is corrected. The starters that never come back have usually been killed by mold, vinegar bacteria, or weeks of neglect at room temperature.
A starter is a living culture of wild yeasts (mostly Saccharomyces and Candida species) and lactic acid bacteria. Both populations need food (flour starches), water, and temperature in the right range to thrive. When the starter slows, one or more of those needs is unmet. The trick is figuring out which.
Step 1: Check the temperature
Temperature is by far the most common cause of a stalled starter. Wild yeast activity roughly halves for every 9 F drop in temperature. A starter that doubles in 6 hours at 76 F will take 12 hours at 67 F and 24 hours at 58 F.
A kitchen that feels comfortable to a human (68 to 72 F) is on the cool end for sourdough. In winter, the actual temperature in a cabinet or on a countertop can drop into the low 60s overnight, even with the thermostat set higher.
The fix is to find a warmer spot. The top of a working refrigerator runs 5 to 10 F warmer than the surrounding room because of compressor heat. The inside of a turned-off oven with the light on holds 5 to 10 F warmer than the kitchen. A heating pad on the lowest setting under a folded dish towel provides a steady 78 to 82 F.
Check the actual temperature with a digital thermometer placed next to the jar for an hour. If the reading is under 72 F, that is almost certainly the problem.
Step 2: Check the feeding ratio
A starter is fed at a ratio of starter to flour to water by weight. Common ratios are 1:1:1, 1:2:2, and 1:5:5. The first number is the starter, the second is the flour, the third is the water.
A 1:1:1 feeding (50 g starter, 50 g flour, 50 g water) gives the yeast a small meal that gets consumed in 4 to 6 hours at 76 F. A 1:5:5 feeding (10 g starter, 50 g flour, 50 g water) provides a much larger meal that takes 12 to 16 hours to consume.
If a starter is fed too little flour for its activity level, the culture exhausts its food and goes dormant before doubling. If it is fed too much (1:10:10 for a sluggish starter), the small surviving yeast population cannot keep up.
For a stalled starter, a 1:5:5 feeding once or twice a day usually restores rhythm within three days. The larger food supply gives the yeast room to multiply rather than just survive.
Step 3: Check the flour
Wild yeasts and bacteria live on the bran of grain. Bleached, highly refined white flour has fewer of both than whole grain flours.
A starter fed only on bleached all-purpose flour will eventually run thin on its microbial population, especially if the flour brand changes. A starter that used to thrive on King Arthur bread flour may stall on a different mill’s flour because the bran content or processing differs.
The fix is to add 10 to 20 percent whole grain rye or whole wheat to each feeding. Rye in particular is high in the enzymes (amylases) and sugars that wild yeasts feed on. Many bakers maintain their starters on a 50/50 rye and bread flour mix permanently and switch to all white flour only for the levain that goes into the dough.
Test this: at the next feeding, replace 10 g of the flour with whole grain rye. Within two feedings, a previously stalled starter often shows visible improvement.
Step 4: Check the water
Chlorinated municipal water suppresses wild yeasts and lactic acid bacteria. A starter that thrived in a previous home may stall after a move to a new city with more aggressive water treatment.
The fix is simple: use filtered water, bottled spring water, or tap water that has been left uncovered in an open container for 24 hours (chlorine evaporates, chloramine does not, so a carbon filter is more reliable). Avoid distilled water, which lacks the minerals the culture also needs.
This is rarely the problem in established starters but is worth checking after a relocation or when municipal water treatment changes seasonally.
Reading the warning signs
Beyond simple sluggishness, a starter can show specific symptoms that point to specific problems.
Hooch on top
A dark gray or amber liquid on the surface is alcohol produced when the yeast has finished its food. This means the starter is hungry. Pour it off or stir it in, then feed sooner or with a larger flour ratio.
Strong vinegar or nail polish remover smell
Acetobacter (vinegar bacteria) have grown in. This usually happens when a starter is left too long between feedings or kept too warm. The fix is aggressive: discard down to 1 tablespoon, feed at 1:10:10 with rye and bread flour mix, and feed twice daily for a week.
Mold (fuzzy spots, pink streaks, orange patches)
Mold is the one symptom that means the starter must be thrown out. Pink and orange in particular indicate harmful bacteria. Start fresh rather than trying to salvage.
Layer separation without rise
Flour settling to the bottom while water rises to the top, without any bubbling or doming, suggests the yeast population has collapsed. Try the rye feeding combined with a warmer spot. If no improvement after 5 to 7 days, start over.
The 7-day revival protocol
For a starter that should be active but is not, this routine revives most cultures.
Day 1: discard all but 2 tablespoons. Feed 50 g flour (40 g bread flour, 10 g whole rye) and 50 g filtered water. Mark the jar level with a rubber band. Place at 75 to 78 F.
Days 2 to 7: discard all but 2 tablespoons each morning. Feed the same mix and amounts. Mark the new level. By day 4 or 5, expect to see the starter double between feedings. By day 7, it should triple reliably.
If by day 7 there is still no rise, the culture is likely dead or the kitchen environment is fighting it. At that point, starting a new starter from scratch is faster than continuing to coax the old one.
A revived starter is fragile for the first two weeks. Feed it more often than usual, keep it at 75 to 78 F if possible, and resist the urge to bake with it until it has tripled between three consecutive feedings on schedule. The patience pays off in dough that rises predictably from then on.
Frequently asked questions
Why is my sourdough starter not rising after feeding?+
The three most common causes are temperature (kitchen too cold, usually under 70 F), feeding ratio off (too much or too little flour relative to starter), or flour problem (overly bleached white flour with too few wild yeasts and bacteria). Move the starter to a warmer spot, switch to a 1:5:5 feeding ratio, and add a tablespoon of whole grain rye or whole wheat flour to the next feeding. Most stalled starters revive within 3 to 5 days.
How long should a healthy starter take to double after feeding?+
A mature, well-fed starter at 75 to 78 F should double in 4 to 8 hours. New starters in the first two weeks may take 8 to 12 hours or fail to double at all. If a starter that previously doubled reliably suddenly takes longer, something has changed (temperature, flour, feeding schedule, or contamination).
What is the dark liquid on top of my starter and is it bad?+
That liquid is called hooch and is alcohol produced by the yeast when the starter has run out of food. It is not dangerous and the starter is still alive, but it signals that the starter needs to be fed more often or with a larger flour ratio. Pour off the hooch (or stir it in for tang) and resume feeding on a tighter schedule.
Can I use chlorinated tap water for sourdough starter?+
Chlorinated water suppresses the wild yeasts and bacteria a starter depends on. Filtered, bottled, or tap water left uncovered for 24 hours (chlorine evaporates) all work. If a healthy starter suddenly stalls after a move, the new tap water is a likely suspect.
How do I revive a starter that has been in the fridge for months?+
Take it out, discard all but 2 tablespoons, feed it 1:1:1 with 50 g flour and 50 g water, and leave it at 75 to 78 F. Discard and feed again in 12 hours, then twice daily for 3 to 5 days. By day 5 a viable starter should be doubling between feedings. If no rise appears by day 7, the culture is likely dead and worth starting fresh.
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Priya Sharma
Priya Sharma writes for The Tested Hub.