Why Is My Sourdough Starter Not Rising Temperature Vs Feeding Ratios

A healthy sourdough starter should double in size within 4–8 hours after feeding, with a domed top, visible bubbles, and a pleasantly tangy aroma. When it doesn’t rise, bakers often grow frustrated—especially after days or weeks of consistent effort. While many assume their technique is flawed, two primary factors dominate starter performance: temperature and feeding ratios. These elements interact dynamically, and understanding their balance is essential for reviving or maintaining an active culture.

Sourdough starters are living ecosystems composed of wild yeast and lactic acid bacteria. Their activity depends on food (flour), water, and environmental conditions. If any of these variables are off, fermentation slows or stalls. This article breaks down how temperature and feeding ratios affect rise, identifies common pitfalls, and provides actionable steps to correct them—so you can build confidence and consistency in your sourdough journey.

The Role of Temperature in Starter Activity

Temperature directly influences microbial metabolism. Yeast and bacteria in your starter thrive within a specific range—too cold, and they become sluggish; too hot, and they die or produce undesirable byproducts.

The optimal temperature for sourdough fermentation is between 75°F and 80°F (24°C–27°C). Within this window, yeast reproduce efficiently and produce carbon dioxide, which creates lift. Below 70°F (21°C), activity slows significantly. Above 85°F (29°C), acetic acid bacteria dominate, increasing sourness but potentially inhibiting rise due to excessive acidity.

Tip: Use an infrared thermometer or digital probe to check your starter’s internal temperature—not just room air—to ensure accuracy.

Cool kitchens are a common culprit behind flat starters. In winter, countertops near windows or exterior walls may drop below 68°F at night, stalling fermentation overnight. Conversely, overheated proofing boxes or sunny sills can push temperatures past 90°F, killing delicate yeast strains.

To stabilize temperature:

• Place the jar in a turned-off oven with only the light on (produces ~75°F).
• Use a seedling mat with a thermostat controller set to 78°F.
• Nestle the jar in a cooler with warm water bottles (replaced every few hours).
• Store near appliances that emit gentle heat, like refrigerators or routers.

“Temperature stability matters more than peak warmth. A steady 76°F will outperform fluctuating highs and lows.” — Dr. Debra Wink, Microbiologist & Sourdough Researcher

How Feeding Ratios Influence Rise and Fermentation

Feeding ratio refers to the proportion of starter, flour, and water added during refreshment. It determines how much food is available relative to the existing microbial population. Common ratios include 1:1:1 (equal parts starter, flour, water) and 1:2:2 (one part starter to two each of flour and water).

Lower inoculation (less starter relative to fresh flour) gives microbes more space and resources to multiply rapidly. Higher inoculation leads to faster acid buildup, which can suppress yeast before peak gas production occurs.

For example:

Feeding Ratio (Starter:Flour:Water)	Effect on Rise Time	Acidity Level	Best For
1:1:1	Slower rise (~8–12 hrs)	High acidity	Mature flavor development
1:2:2	Moderate rise (~6–8 hrs)	Moderate acidity	Balanced maintenance
1:4:4	Faster rise (~4–6 hrs)	Low acidity	Boosting weak starters
1:5:5 or higher	Rapid rise (~3–5 hrs)	Very low acidity	Rebuilding dormant cultures

If your starter isn’t rising, consider switching to a lower inoculation ratio. Reducing starter from 1:1:1 to 1:4:4 effectively “resets” the pH and dilutes accumulated acids, giving yeast a clean slate to ferment vigorously.

Tip: When reviving a sluggish starter, use a 1:5:5 feeding ratio twice daily for 2–3 days before returning to maintenance levels.

Interplay Between Temperature and Feeding: Real-World Dynamics

Temperature and feeding ratios don’t act independently—they amplify or counteract each other. A high feeding ratio (e.g., 1:5:5) may still fail if the environment is too cold. Conversely, even ideal temperatures won’t rescue a starter buried under acidic waste due to over-inoculation.

Consider this scenario:

Mini Case Study: Reviving a Dormant Starter in Winter

Sarah kept her rye starter in a drafty kitchen corner where temps averaged 66°F. She fed it 1:1:1 every 24 hours. After three days, it showed minimal rise and a layer of grayish hooch. Discouraged, she nearly discarded it.

Instead, she moved the jar to a cabinet above her fridge (measured at 78°F) and switched to 1:4:4 feedings every 12 hours using unbleached all-purpose flour. By day two, bubbles appeared throughout. On day three, it doubled within five hours. She returned to 1:2:2 maintenance and now uses it weekly for sandwich loaves.

This illustrates how adjusting both variables simultaneously can break a stagnation cycle. Cold suppressed activity; high inoculation allowed acid accumulation. Correcting both restored balance.

Step-by-Step Guide to Diagnose and Fix a Non-Rising Starter

Follow this timeline to assess and reactivate your starter within 72 hours:

1. Day 1 – Morning: Discard all but 20g of starter. Feed with 80g flour and 80g lukewarm water (78°F). Use a neutral flour like all-purpose or bread flour. Place in a clear container marked with a rubber band at the starting level.
2. Day 1 – Evening: Repeat the same feeding (20g starter → 80g flour + 80g water). Move to a consistently warm spot (use heating pad if needed).
3. Day 2 – Morning: Observe volume and bubble structure. If no rise, repeat 1:4:4 feeding. Smell for ripe fruitiness rather than nail polish or vinegar sharpness.
4. Day 2 – Evening: Continue 1:4:4 feedings. Check for sustained bubbling over 30 minutes post-feed.
5. Day 3 – Morning: If rising steadily, switch to 1:2:2. Confirm doubling within 6–8 hours. If successful, your starter is ready for baking.
6. Day 3 – Evening: Optional test: Perform a float test (drop ½ tsp starter into room-temp water). If it floats, it’s producing enough gas to leaven bread.

This protocol prioritizes rapid microbial growth while minimizing acid stress. It works even for starters pulled from refrigeration after months of dormancy.

Common Mistakes That Mimic Temperature or Feeding Issues

Even with proper ratios and warmth, other errors can prevent rise:

• Using chlorinated tap water: Chlorine kills beneficial microbes. Use filtered or bottled water if your tap is heavily treated.
• Inconsistent flour type: Switching frequently between whole grain, white, or bleached flours destabilizes microbial colonies. Stick to one reliable flour during revival.
• Infrequent feeding: Going beyond 24 hours between feeds allows acid to accumulate excessively, especially at room temperature.
• Sealed containers: Tight lids trap CO₂, creating false puffiness without real structure. Always use loosely covered jars.

Checklist: Is Your Starter Set Up for Success?

Before concluding your starter is unhealthy, verify these basics:

• ✅ Temperature is stable and within 75–80°F (24–27°C)
• ✅ Feeding ratio is appropriate (try 1:4:4 if inactive)
• ✅ Fed every 12 hours if at room temperature
• ✅ Using non-chlorinated water
• ✅ Flour is fresh and unbleached
• ✅ Container allows gas escape (lid resting on top, not screwed tight)
• ✅ No mold or pink/orange discoloration (discard if present)

Frequently Asked Questions

Can I keep my starter in the fridge if it's not rising at room temperature?

No—refrigeration halts activity further. First restore vitality at room temperature with frequent, diluted feedings. Only once doubling reliably should you store it long-term in the fridge with weekly feedings.

Why does my starter rise a little then collapse?

This usually means it’s peaking too early and running out of food. Either the feeding ratio has too much starter (e.g., 1:1:1), or the temperature is too high. Reduce inoculation or cool the environment slightly to extend peak window.

Does whole wheat or rye starter rise less than white flour starter?

Whole grain starters often appear denser due to fiber content, but they can be highly active. However, they acidify faster, so they may need more frequent feeding or lower inoculation to maintain rise. Rye starters typically peak earlier—sometimes in 4–5 hours—requiring closer monitoring.

Conclusion: Consistency Over Perfection

A sourdough starter that won’t rise isn’t broken—it’s communicating. Temperature and feeding ratios are its language. By listening through observation and adjusting methodically, most starters respond within days. The key is consistency: regular feedings, stable warmth, and patience. Don’t chase quick fixes or exotic flours until the foundation is strong.

Once your starter doubles reliably, you’ll gain confidence not just in fermentation science, but in your ability to nurture living systems. That skill extends far beyond bread—it’s at the heart of all fermented foods.

🚀 Start tonight: Adjust your feeding ratio to 1:4:4 and find a warmer spot. Track changes over the next 48 hours. Share your progress or questions in the comments—your experience could help another baker breakthrough.