Sourdough Starter Not Rising? 10 Causes and How to Fix Them

A starter that won’t rise is one of the most frustrating parts of learning sourdough, mostly because the cause is invisible. The good news: starters are hard to kill. In almost every case, a flat starter is cold, hungry, too young, or quietly rising and falling at a time you’re not looking.

Work through this checklist in order. The top causes are by far the most common.

Quick diagnosis

What you see	Most likely cause	Jump to
Rose well on day 2–4, now nothing	Normal quiet phase of a new starter	Cause 2
Very slow everything, kitchen feels cool	Temperature	Cause 1
Streaks on the glass above the starter	It peaked while you were away	Cause 3
Lots of bubbles, little rise, runny	Too much water	Cause 6
Grey liquid on top, nail-polish smell	Hungry and over-acidic	Cause 7
Rises only a little, even when warm	Flour, ratio or feeding too early	Causes 4, 5, 10
Fuzzy spots, pink or orange streaks	Mold or contamination	When to start over

1. Your kitchen is too cold

This is the number one reason. Starter microbes slow down a lot as temperature drops. A starter that peaks about 3½–5 hours after a 1:1:1 feed at 24°C (75°F) can take 5½–8 hours or more at 18°C (65°F), and a sluggish or young one longer still. If you’re checking at the “usual” time, it looks like nothing is happening. The sourdough starter peak chart shows typical times for every temperature, and the rise forecast estimates today’s for your kitchen.

Fix:

• Aim for about 24–27°C (75–80°F).
• Feed with water warmed to around 27°C (80°F).
• Find a warm spot: on top of the fridge, near (not on) a radiator, or in the oven with only the light on. Put a thermometer in there first; an oven light can make it warmer than you want, so leave the door slightly open if needed.
• Be patient in winter. Check again a few hours later than you normally would.

2. It’s a new starter in the quiet phase

Almost every new starter does this. You mix flour and water, and by day 2 or 3 it has bubbled up impressively, maybe even doubled. Then it goes flat, sometimes with a strange smell, for several days.

That first surge is commonly attributed to bacteria that thrive in a fresh, not-yet-acidic mixture. As the starter becomes more acidic, they die back, and the wild yeast and lactic acid bacteria that make a stable starter take a while to take over. It’s a normal stage, not a failure.

Fix:

• Keep feeding on schedule, once or twice a day, discarding down each time.
• Keep it warm (see cause 1).
• Adding some whole wheat or rye flour helps (see cause 5).
• Some bakers use unsweetened pineapple juice instead of water for the first couple of days to make the mix acidic sooner. It’s optional.
• Expect a new starter to take one to two weeks, sometimes longer, before it reliably doubles.

3. It peaked while you weren’t looking

A lively starter at warm temperatures can rise and fall within a few hours. Feed it before bed and by morning it has already collapsed back down.

Fix: look at the inside of the jar. Dried streaks or a film above the current surface show how high it got. Put a rubber band at the level right after feeding so you can see the rise clearly, or feed at a time when you can check every hour or two. If this is the issue, your starter is fine. You just need to learn when it peaks.

4. The feeding ratio is too big for your temperature

Big ratios like 1:5:5 or 1:10:10 are great for once-a-day feeding, but they dilute the starter a lot. In a cool kitchen, a 1:10:10 feed can take 16 hours or more to peak. Give up after 8 hours and it looks dead.

Fix: go back to 1:1:1 or 1:2:2 every 12 hours for a few days until it’s reliably doubling, then increase the ratio if you want. The starter feeding calculator makes switching ratios easy.

5. The flour isn’t giving it enough to eat

White flour works, but it has less of the nutrients and wild microbes that whole-grain flours carry. Bleached flour can be slower still.

Fix:

• Use unbleached flour.
• Replace 10–25% of the feed flour with whole wheat or rye. Rye especially tends to wake up a sluggish starter.
• Expect a short adjustment when you change flours. Give it a few feeds before judging.

6. It’s too runny (or too stiff)

At 100% hydration, a starter should look like a thick pancake batter. If you measure by volume (cups) instead of weight, it’s easy to add too much water, because a cup of flour weighs much less than a cup of water. A runny starter makes plenty of bubbles but can’t hold the gas, so it never climbs the jar.

A very stiff starter has the opposite problem: it rises slowly and tends to crack rather than dome.

Fix: weigh your flour and water. If it still looks thin, reduce the water by 10–20% for a few feeds and watch whether it starts to rise. The hydration calculator can help if you’re converting a starter to a different consistency.

7. It’s hungry and over-acidic

Grey liquid on top (hooch), a sharp vinegar or acetone smell, and a sluggish rise all point to a starter that has gone too long without food. The acidity builds up and slows the yeast.

Fix: pour off the hooch, discard most of the starter (keep 10–20 g), and feed at 1:2:2 or 1:5:5 with warm water. Repeat every 12 hours. Discarding generously lowers the acidity quickly, and two or three feeds usually bring back the rise.

8. Chlorine or chloramine in the water

Treated tap water rarely hurts an established starter, but it can slow a new or struggling one.

Fix: if you’ve ruled out temperature, flour and ratio, use filtered or bottled water for a few days as a test. Leaving tap water out overnight lets chlorine escape, but many water systems use chloramine instead, which doesn’t evaporate.

9. The jar is hiding the rise

In a wide bowl or a big jar with a small amount of starter, a real rise spreads out and barely changes the level. Very tapered jars make it hard to judge too.

Fix: use a straight-sided glass jar roughly two to three times the volume of your starter. Mark the level after each feed. A loosely fitting lid is fine; you don’t need an airtight seal.

10. You’re feeding before it has peaked

Feeding on a strict clock is convenient, but if the starter hasn’t had time to rise before you discard and feed again, each feed dilutes a population that never got going. This happens most in cool kitchens with twice-a-day feeding.

Fix: wait until the starter has clearly risen, even if that means feeding every 16 or 24 hours for a while. Once it’s strong and doubling, you can return to a regular schedule. Our feeding schedule guide has routines for different temperatures.

When to start over

Very few problems require a new starter. Throw it out if you see:

• Fuzzy mold of any color on the surface
• Pink, orange or red streaks

Hooch, a dark film, sharp or cheesy smells, and long periods of inactivity are all recoverable.

A 3-day revival plan

For an established starter that has gone sluggish:

Time	What to do
Day 1, morning	Pour off hooch. Keep 20 g. Feed 1:2:2 with 25% whole wheat or rye, warm water. Keep at 24–27°C.
Day 1, evening	Keep 20 g, feed 1:2:2 again, even if it rose only a little.
Day 2	Repeat twice. Mark the jar and note how high it rises.
Day 3	If it doubles within about 4–8 hours, it’s back. If not, keep going and review causes 1, 6 and 8.

How Boulie helps

Troubleshooting is much easier with a record. In Boulie, each feed you log includes the ratio, flour and kitchen temperature, so you can see whether the slow days line up with a cold snap or a flour change. The photo rise check lets Boulie’s AI read the jar and tell you how the rise looks, and rise trends show whether your starter is getting stronger over a week of revival feeds. Counter or fridge, reminders follow the mode your starter is in, which helps with cause 7.

Key takeaways

• Check temperature first. Cold is the most common reason a starter “won’t rise”.
• New starters go quiet after an early false rise. Keep feeding.
• Look for streaks on the jar before assuming nothing happened.
• Weigh ingredients, use some whole grain, and go back to small ratios while you recover.
• Only mold or pink/orange streaks mean starting over.