Beginner Guide
Sourdough Starter Not Doubling? 9 Practical Fixes
If your starter isn't doubling in 4–8 hours after a feed, the temperature, flour, or feed ratio is usually wrong.
Short answer: a healthy starter doubles in 4–8 hours at 75°F after feeding 1:1:1 with bread flour. If yours doesn't, the most likely cause is cold temperature, weak flour, or a too-large feed ratio.
How long should it take?
A starter at peak vigor:
- 1:1:1 feed at 75°F: doubles in 4–6 hours
- 1:1:1 feed at 68°F: doubles in 8–12 hours
- 1:5:5 feed at 75°F: doubles in 8–10 hours
- 1:10:10 feed at 75°F: doubles in 10–14 hours
If it's taking longer, work through these causes.
The 9 fixes ranked
| # | Cause | Quick test | Fix |
|---|---|---|---|
| 1 | Too cold | Water/jar feels cool | Warm to 75–80°F |
| 2 | Weak flour | Cake flour, AP | Use bread or whole wheat |
| 3 | Feed ratio too small | Used 1:0.5:0.5 | Switch to 1:1:1 minimum |
| 4 | Chlorinated water | Tap water | Filtered or rested |
| 5 | Acidic build-up | Gray, sharp smell | Refresh 2–3 times |
| 6 | Recent fridge nap | Just out of cold | Refresh on counter for 2 days |
| 7 | New starter | <14 days old | Wait, don't worry |
| 8 | Wrong jar | Tall, narrow | Use straight-sided wide jar |
| 9 | Compromised culture | Off color, mold | Rebuild from scratch |
1. Temperature
Yeast and bacteria slow dramatically below 70°F. A starter that "doesn't work" in a 65°F kitchen often works fine when moved to a 78°F spot.
Solutions:
- Use a proofing box
- Place near a window with sun
- Use the oven with light on (creates 75–80°F)
- Use warm water for feeds
2. Flour quality
Bleached, low-protein flours feed yeast slowly. A starter on:
- All-purpose: doubles slowly
- Bread flour: doubles well
- Whole wheat or rye: doubles fast (more enzymes and minerals)
For a sluggish starter, add 25% whole wheat to your next feed. The extra enzymes kickstart it.
3. Feed ratio
A small feed (1:0.5:0.5) doesn't refresh enough nutrients. A large feed (1:5:5 or 1:10:10) is great for vigor but slow to double.
For everyday maintenance: 1:1:1 by weight (e.g., 50g starter + 50g flour + 50g water).
4. Water quality
Chlorinated tap water inhibits yeast. Test by leaving water out overnight (chlorine evaporates) or use filtered water.
Some starter problems clear up immediately when you switch to filtered or bottled water.
5. Acid build-up
If a starter hasn't been fed in days, acid accumulates. The yeast slows because the environment is too acidic.
Fix:
- Discard most of the starter
- Refresh 1:1:1
- Repeat every 12 hours for 2–3 cycles
- Activity should return
6. Just out of fridge
A starter that's been in the fridge for a week is slow for the first feed or two. Don't expect it to double immediately.
Plan:
- Day 1: pull from fridge, feed 1:1:1, leave on counter
- Day 2: feed again, watch for activity
- Day 3: should be doubling
7. New starter
A starter under 14 days old is still developing. It might rise in 12 hours but not double; or double once, then stall.
Be patient. By day 14–21, most starters reach reliable doubling vigor.
8. Wrong jar
A tall narrow jar makes it hard to see if the starter is "doubling" — visual judgment fails.
Use a straight-sided wide jar (mason jar, weck jar). Mark the level after feeding with a rubber band. Doubling is when the rubber band hits the new level.
9. Compromised culture
If your starter:
- Smells like vomit, paint thinner, or rotten eggs
- Has pink, orange, or green streaks
- Has visible mold
Discard. Start over. These are not fixable.
A 3-day revival protocol
For a sluggish but otherwise healthy starter:
Day 1, morning:
- Discard most, keep 10g
- Feed with 50g whole wheat flour + 50g water (warm)
- Place at 78°F
Day 1, evening (12h later):
- Discard, keep 10g
- Feed with 50g bread flour + 50g water (warm)
Day 2, morning:
- Should see activity (bubbles, slight rise)
- Repeat with 1:1:1 bread flour
Day 2, evening:
- Should see doubling within 6 hours
Day 3:
- Healthy starter, ready to bake
When doubling isn't necessary
Some starters never quite double but produce excellent bread. Activity matters more than doubling per se. Look for:
- Visible bubbles throughout
- A dome or peak that rises and falls
- A clean, fermented smell
- A float test that works (a spoonful floats in water)
If all four are true, your starter is fine even if it doesn't fully double.
The one-day diagnosis
If you suspect your starter is fine but proving slow:
- Take 20g, mix with 100g flour and 100g water
- Mark the level
- Wait 6 hours at 75°F
- If it's at 50% rise: starter is fine, just slow to double. Use a longer levain build.
- If still at 0%: starter has issues, work through the 9 fixes.
This levain test is the cleanest way to see what your starter actually does.
Don't overreact
A starter that doesn't double on day 5 of being established is normal. A starter that's been doubling for months and suddenly stops is a real problem.
Track patterns over weeks, not single feeds. Most starter "issues" resolve on their own with patience.