Why Is My Sourdough Starter Not Rising? Root Causes
By Maya Ellison · Updated August 18, 2026 · 3 min read
The short answer
A flat jar is the most common sourdough problem in the world, and the most common cause of panic. The companion fix guide tells you what to do; this page explains why your sourdough starter is not rising in the first place. Understand the root cause and the fix stops being guesswork.
Diagnose before you fix
Ask three questions before you change anything:
- What does the jar look like? Completely flat and silent points to temperature or flour. Bubbly but no volume points to consistency or ratio.
- How warm is the spot it lives in? Measure the actual counter, not the room you assume it is. Most kitchens hover near 68°F (20°C), which is marginal for starter.
- What did you feed it, and how long ago? A 1:1:1 feed is a maintenance dose. A 1:5:5 feed is a marathon for a small colony.
Answer those three and you'll usually know the cause before you finish this page.
The root causes, in order
| What you see | Root cause | How to confirm |
|---|---|---|
| Completely flat, no bubbles | Too cold, or bleached flour | Feel the jar; check the flour bag |
| Bubbles but no rise | Too watery, or ratio too large | Stir it — batter or paste? |
| Rises, collapses within an hour | Over-hungry starter | Layer of hooch on top |
| Never has risen, week one | Starter too young | Check the calendar |
Root cause 1: temperature
Sourdough is a temperature equation, and the starter is the most sensitive part of it. Below roughly 65°F (18°C) the yeast and bacteria slow to a crawl — they don't die, they idle. A starter at 60°F (15°C) can take 16–24 hours to peak. The same starter at 75°F (24°C) peaks in 4–6 hours. A "slow" starter is usually just a cold starter.
Root cause 2: feeding ratio
A starter is a population, not a recipe. Feed it 1:1:1 (starter, flour, water by weight) and the microbes double comfortably. Feed it 1:5:5 and you've handed a small colony a banquet it can't process — it spends days eating instead of multiplying, and the jar sits flat. The fix is rarely more food. It's a smaller meal, more often.
Root cause 3: chlorinated water
Municipal tap water is treated to kill microbes, and your starter is microbes. Chlorine doesn't always stop a starter, but it slows one down — and slow shows up as no rise. Leave tap water out in an open jug overnight and the chlorine evaporates, or use filtered water. On a well? Skip this cause entirely.
Root cause 4: flour choice
Flour is the starter's only food, and not all flour feeds equally. Bleached all-purpose flour ferments noticeably slower than unbleached, while whole wheat and rye carry extra nutrients and wild yeast. If your starter never truly comes alive, switching to unbleached flour — or doing one rye feeding a day for a week — often does what extra time never will.
Root cause 5: starter age
A brand-new starter goes through a quiet stretch between days 3 and 7: the initial bacterial bloom fades, and the yeast population hasn't caught up yet. It can look completely dead. That's not failure; it's a transition. Keep the daily 1:1:1 feeding and the rise arrives once the yeast reaches critical mass — usually around day 7–10, exactly as the beginner's guide to sourdough lays out.
When the cause points to the fix
Once you know which root cause you have, the remedy is mechanical: warm the jar, cut the ratio, change the water, swap the flour, or wait out the age. Walk through each fix in exact steps on the companion guide, and if your starter is bubbling without gaining volume, the thick-paste problem is covered there too. If your starter has never been reliable, start again from scratch with the starter guide, or jump straight to the troubleshooting hub.
Frequently asked questions
Why is my sourdough starter not rising even though it bubbles?
Bubbles mean fermentation is happening; no volume means the starter can't trap gas. The usual cause is a too-watery starter or a feeding ratio above 1:1:1. Stiffen it to a thick paste and feed at 1:1:1 for a couple of days.
Is a cold kitchen the real reason my starter isn't rising?
Usually, yes. Below 65°F (18°C) the microbes slow down sharply, and most kitchens sit in the 60s. Find a warm spot — top of the fridge, next to a router — and most mystery flat starters rise within a day.
Why does my starter start rising after I switch flour?
Flour is the starter's only food, and bleached or heavily processed flour ferments far slower than unbleached flour, whole wheat, or rye. Whole-grain flours carry more nutrients and wild yeast, which is why new starters are usually started on rye or whole wheat.
Can my starter be too young to rise?
Yes. A starter under two weeks old is still building its microbial population and may rise slowly or not at all for the first week. Keep feeding it 1:1:1 daily; the rise arrives once the population reaches critical mass.
What's the difference between this page and the fix page?
The fix page assumes the cause and gives you the remedy. This page explains the why: how temperature, feeding ratio, chlorine, flour, and starter age each stall a rise, so you can tell which cause you have before you change anything.