Why Your Sourdough Came Out Flat (And the Fix)

A flat sourdough — wider than tall, no oven spring — is one of the most disappointing outcomes. Here are the five most common causes and the specific fix for each.

The five usual suspects

1. Overproofed during the final proof

The most common cause. Your dough rose too long after shaping. The yeast exhausted itself, the gas-trapping structure collapsed, and there's nothing left to spring.

Signs: dough was very puffy in the basket, possibly sunken on top. Dough doesn't spring back when poked.

Fix: shorter final proof. If cold retarding, reduce to 12 hours instead of 24.

2. Underproofed during bulk fermentation

The opposite cause but similar result. The dough wasn't fermented enough — gas bubbles never developed properly. There's nothing to spring because there's nothing inflated yet.

Signs: dough was small in the basket, dense feeling. Cuts cleanly without being airy.

Fix: longer bulk fermentation. Look for 50–70% rise.

3. Weak gluten structure

The dough has gas but can't hold it. Bubbles burst as they form. The dough spreads instead of springing up.

Signs: dough was wet and slack, didn't shape well, didn't hold a tight skin.

Fix: more folds, longer autolyse, higher-protein flour, or lower hydration.

4. Weak starter

A starter that isn't strong enough to leaven the dough. The dough may rise slightly but doesn't generate the explosive oven spring.

Signs: bulk took 50% longer than expected. Starter at peak was sluggish.

Fix: feed your starter twice daily for a week before baking. Use a freshly built levain at peak.

5. Over-handled at shaping

Aggressive shaping deflates the gas you've built. The dough goes into the basket already partially deflated, then loses more during the proof.

Signs: shaping was complicated, took multiple attempts, surface was beat up.

Fix: gentle, confident shaping. One pre-shape, one final shape. No "fixing."

The diagnosis flowchart

Look at your flat loaf:

Was the dough very large in the basket before baking?

• Yes → overproofed
• No → continue

Did the dough hold a tight, smooth shape after shaping?

• No → weak gluten or aggressive shaping
• Yes → continue

Was bulk fermentation timing standard?

• Too fast → starter possibly too active, or kitchen too warm
• Too slow → underproofed or weak starter

Did the loaf show oven spring at all (bigger after baking)?

• No spring → underproofed or weak starter
• Some spring → likely overproofed

A test for next bake

Bake the same recipe with these changes:

• 30% shorter final proof
• 4 sets of folds (not 3)
• Build a fresh levain (not direct from mother)
• Verify dough temperature (75°F)
• Use the poke test before baking

If the loaf still comes out flat, the issue is more fundamental — likely a weak starter or wrong flour.

The poke test

Press a finger into the side of the dough about 1/2 inch deep:

• Springs back immediately → underproofed (give it more time)
• Springs back slowly → ready to bake
• Doesn't spring back at all → overproofed

This test is more reliable than time.

Salvaging the flat loaf

A flat sourdough is still edible:

• Slice for sandwiches (smaller, denser, but works)
• Cut into croutons
• Use for bread pudding
• Toast for bruschetta

The bread isn't ruined. It's just a different bread than you planned.

Why bakery sourdough is so tall

Professional bakers have:

• Rock-solid starter routines (never weak)
• Precision dough temperature
• Walk-in coolers for cold retards (consistent temperature)
• Years of feel for shaping
• Steam injection ovens

You're not competing with that. You're working with home variability. A 70–80% as-tall sourdough is great for a home baker.

The single biggest improvement

If you've been getting flat loaves consistently, do this:

1. Feed your starter every 12 hours for a week
2. Build a 1:5:5 levain the night before
3. Use the levain only when it's at peak (passes float test)
4. Bake the same recipe you've been using

You'll usually see immediate improvement. Most flat loaves are a starter strength issue.

When the recipe is wrong

Some recipes call for very long cold retards (36+ hours). For weak starters, this is too long. The dough overproofs.

If a recipe consistently gives flat loaves:

• Reduce cold retard to 12 hours
• Or build a stronger starter
• Or switch to a different recipe

Recipes are tuned for the author's starter, kitchen, and oven. Adapt to yours.

Track conditions

Keep a baking log:

• Dough temperature at mix
• Bulk fermentation time
• Cold retard time
• Final loaf shape
• Notes on any anomalies

After 10 bakes, patterns emerge. You'll see what conditions produce flat loaves and what produces tall ones.

The realistic expectation

Expect flat loaves occasionally even when you're experienced. Sourdough has variability. A bad starter day, a warmer kitchen than expected, a missed timing — all can produce a flat loaf.

What matters is the average. If 7 of 10 loaves are well-risen, you're doing well.

The patience principle

Most flat loaves are caused by impatience (rushed bulk, rushed proof) or over-confidence (timing not adjusted for kitchen temp). Slow down, observe the dough, trust the visual cues over the clock, and your average loaf height will rise dramatically.