Why is my sourdough starter not rising? (And how to fix it)

Cause 1: Your kitchen is too cold

If your starter is not rising, this is the answer about 60 percent of the time. Sourdough yeast and lactic acid bacteria are temperature-sensitive in a way that is easy to underestimate. The numbers:

• 78°F (26°C): Active and fast. A healthy starter doubles in 3 to 5 hours.
• 72°F (22°C): Normal. Doubles in 5 to 8 hours.
• 68°F (20°C): Slow. Doubles in 8 to 12 hours, sometimes longer.
• Below 65°F (18°C): Sluggish to dormant. Many home bakers think their starter is dead at this temperature.

The thermostat reading is not the same as the temperature inside your jar. A jar of starter sitting on a cold kitchen counter, especially in winter or in an air-conditioned home, can be 5–8°F below room temperature. If your kitchen reads 70°F, the starter itself may be at 64°F.

If you want to be exact about it, an instant-read thermometer ends the guessing. Stick the probe into the starter itself for a couple of seconds. Knowing the actual temperature is worth more than any other piece of equipment in sourdough.

Warmer is not automatically better, and there is a ceiling worth knowing about. The yeast in a starter grows fastest at 27°C (81°F) while the bacteria keep accelerating to 32 or 33°C, so pushing the jar too warm buys you acid rather than rise. The measured numbers are in sourdough fermentation temperature.

The false rise: bubbling on day 3, flat by day 4 (new starters only)

A pattern that confuses almost every new sourdough baker:

1. Days 1–2: Nothing visible. Normal.
2. Days 2–3: Lots of bubbles, often a dramatic rise. The baker thinks it is ready.
3. Days 3–7: Activity falls off a cliff. Sometimes no rise at all for several days. The baker panics and either over-feeds or throws it out.
4. Days 7–14: Gradual return to consistent doubling.

This is called the false rise, and it is the single most common reason a new starter gets thrown out. The early bubbles are not the right yeast. They are mostly from Leuconostoc bacteria, which produce gas but no useful fermentation for bread. As the culture matures, these bacteria die off and the wild yeast you actually want (mostly Saccharomyces and Candida strains) takes over. That handoff is invisible. From the outside it looks like the starter has died.

It has not. Keep feeding on schedule. The recovery is not subtle when it arrives.

Cause 3: The flour is the problem

Once temperature and timing are right, flour is the next variable. A few patterns:

• All-purpose or bread flour on a new starter often produces a slow first week. White flour has the bran and germ removed, which means it has fewer of the wild yeasts and bacteria a new culture needs to establish itself.
• Bleached or bromated flour can inhibit microbial activity outright. Read the bag. Look for "unbleached" and the absence of "bromate" or "bromated."
• Old flour loses microbial activity over months. A bag that has been open in a humid kitchen for six months is not the same as a fresh bag.

The single fastest way to wake up a stalled starter is to switch to whole-grain rye for a feed or two. The bran in rye carries a microbial population that white flour simply does not have. We covered this in detail in our guide to the best flour for a sourdough starter: rye outperforms white flour for starter work by a wide margin, even for cultures that have been on white flour for months.

Cause 4: The feed ratio is off

"Feed ratio" means the proportion of existing starter to new flour and water you add at each feed. Common ratios:

A common mistake is too much starter relative to new flour. Feeding 1:1:1 with a stalled starter often makes things worse because the existing acidic environment overwhelms the fresh flour before the yeast can act. Counterintuitively, more dilution, not less, often helps a stalled starter recover. Try 1:5:5 for two days, kept warm.

Cause 5: You're not weighing it

If you are measuring starter, flour, and water by volume — tablespoons, cups, "about half a jar" — you are introducing inconsistency that compounds. A cup of flour can vary by 30 percent in actual weight depending on how scooped or settled it is. A cup of starter can vary by 50 percent. Two feeds that look identical by eye can be wildly different by weight.

The fix is a kitchen scale. Any scale that reads to 1 gram is enough; you do not need anything fancy. We recommend the OXO Good Grips 11-pound stainless steel scale as the default — it's accurate to 1 gram, has a pull-out display so large bowls do not block the readout, and the build quality is heirloom-level. Around $50, lasts a decade.

For weighing starter, flour, and water

OXO Good Grips 11-Pound Stainless Steel Food Scale

The default home-baker scale. Reads in 1-gram increments, has a pull-out display so large bowls do not block the readout, runs on AAA batteries, and survives years of flour spills. Cook's Illustrated recommended for over a decade.

Check on Amazon →

Cause 6: The starter is too dirty

Less common but worth checking. If your starter has not been transferred to a clean jar in a few weeks, dried film around the inside of the jar contains the most acidic, least active part of the culture. When you feed, that residue gets pulled back in and acidifies the new flour faster than the yeast can rise it.

The fix is a one-minute transfer. Spoon the active part of the starter into a fresh jar, then feed normally. Wash the old jar. Done.

Is my sourdough starter dead, or just sluggish?

Almost certainly sluggish. A sourdough starter is very hard to kill, and the three signs below are the only ones that mean the culture is actually dead rather than stalled. Heat is the main way people genuinely kill one: the yeast starts dying around 120°F and the bacteria follow by about 130°F, which is why water straight from a hot tap can end a starter in a single feed.

• Visible mold: pink, orange, fuzzy white, or black patches on the surface or sides. Not the same as the white film (kahm yeast) that sometimes appears on neglected starters, which is harmless but signals it's time to refresh.
• Putrid smell: not sour, not vinegary, not yeasty, but actively rotten. A healthy starter smells like sourdough bread or like the inside of a brewery. A dead one smells like garbage.
• Two full weeks of consistent feeds at 75°F with no response. Expect the first signs of recovery within two or three days of correcting the conditions. Two weeks is the outer limit: if it has had warmth and consistent feeds for that long with nothing at all, the microbial population is gone. Start a new one.

Almost every "dead" starter we've seen people throw out was actually a starter that hadn't been given the right conditions for long enough. Patience plus warmth solves most of these problems.

If the starter has been sitting unfed for weeks or months rather than misbehaving on a normal schedule, that is a different job with a different timetable. See how long a sourdough starter can go without feeding for a revival protocol matched to how long it was neglected.

Related reading

• The best flour for a sourdough starter. Why whole-grain rye outperforms white flour, and the brands worth buying.
• Why is my sourdough dense?. Once the starter is working, the dough has its own problems.
• Sourdough starter smells like acetone? The other thing a hungry starter does, and the feeding ratio that clears it.
• Best sourdough starter kit. The actual gear worth owning.

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