Sourdough Guide
Sourdough is bread made with a live culture of wild yeast and bacteria instead of commercial yeast. The process is slower and more variable, but the payoff is flavor complexity and a crust that commercial yeast can't replicate. Most failures come from one source: not reading the dough, and following the clock instead.
The Starter
The starter is a living culture of wild yeast and lactic acid bacteria, kept alive by regular feedings of flour and water. It's what makes sourdough work — and it needs to be active before you bake.
Feeding
A standard feeding ratio is 1:1:1 — equal parts starter, flour, and water by weight (e.g. 50g starter + 50g flour + 50g water). Some bakers use 1:5:5 or 1:10:10 for a slower, more manageable rise, especially in warm weather.
- Feed at room temperature when baking. The starter should peak (reach maximum rise) within 4–8 hours, depending on temperature.
- Store in the fridge between bakes. Feed once a week to keep it alive. Take it out the night before baking and feed it to wake it up.
The float test
Drop a small spoonful of starter in water. If it floats, it has enough gas trapped in it and is ready to use. If it sinks, it needs more time or another feeding.
More reliable: watch for the starter to at least double in size after feeding, with a domed top and bubbles throughout. Use it at or just past peak — before it starts to collapse.
Discard
Every feeding produces more starter than you need. The portion you remove before feeding is discard — it's not active enough to leaven bread but is perfectly good for pancakes, crackers, flatbreads, and waffles. Don't throw it out.
The Levain (Optional)
A levain is a separate small starter build made specifically for one bake, using a portion of your main starter. It lets you control the fermentation speed and flavor profile for that loaf without altering your main starter.
- Build the levain 4–12 hours before mixing the dough, depending on the ratio and temperature.
- A stiff levain (less water) ferments more slowly and produces a milder flavor. A liquid levain ferments faster and produces more tang.
- Many home bakers skip the levain and use the main starter directly — this works fine.
Sourness
Tang comes from lactic and acetic acid produced by bacteria during fermentation. You can control it:
More sour:
- Longer, cooler fermentation
- Higher whole wheat or rye percentage (bacteria prefer complex sugars)
- Stiffer levain
- Longer cold proof
Less sour:
- Shorter, warmer fermentation
- White flour only
- Liquid levain
- Bake same day without cold proof
The Process
1. Autolyse
Mix flour and water (no starter, no salt) and let it rest for 30–60 minutes. This hydrates the flour and begins gluten development passively, making the dough easier to work later. Salt and starter are added after the rest.
Not strictly required but makes a noticeable difference in dough extensibility.
2. Mix
Add the starter and salt after autolyse. Mix until fully incorporated. The dough will be shaggy and sticky — this is normal at high hydration.
3. Bulk fermentation
This is the most important phase and the one most sensitive to temperature. The dough should grow 50–75% in volume — not necessarily double, especially for sourdough.
Signs bulk ferment is complete:
- Dough has grown visibly and feels airy, not dense
- Bubbles on the surface and sides of the container
- Jiggles like jello when you shake the container
- Smooth, domed top
Temperature guide:
- 75°F → ~4–5 hours bulk
- 70°F → ~6–8 hours bulk
- 65°F → ~10–12 hours bulk
- Fridge (~38°F) → 12–16 hours (cold bulk — produces more sour flavor)
4. Stretch and fold
During bulk ferment, instead of kneading, you develop gluten through stretch-and-fold sets. Every 30 minutes for the first 2 hours, grab one side of the dough, stretch it up, and fold it over. Rotate 90° and repeat 4 times.
This builds structure without degassing the dough. After 3–4 sets the dough will feel noticeably stronger and hold its shape better.
5. Pre-shape
Turn the dough onto an unfloured surface and shape it into a rough round, using the surface tension to build a tight skin. Let it rest uncovered for 20–30 minutes (bench rest).
The unfloured surface is intentional — slight sticking helps you build tension.
6. Final shape
Shape into a boule (round) or batard (oval). The goal is a tight, smooth surface with good surface tension — this holds the loaf together during oven spring.
Place seam-side up into a floured banneton (proofing basket) or a bowl lined with a floured cloth.
7. Cold proof (retard)
Cover and refrigerate overnight (8–16 hours). Cold proofing:
- Slows fermentation for more flexibility on baking time
- Develops more sour flavor
- Makes scoring much easier — cold dough holds its shape under the blade
- Improves oven spring
You can bake straight from the fridge — no need to bring to room temperature.
8. Score
Score the loaf with a sharp blade (lame or razor) immediately before baking. This controls where the bread opens during oven spring.
- A simple single slash at 30–45° angle is the most reliable for beginners
- The slash should be decisive and quick — hesitation tears instead of cuts
- Depth of about ½ inch
Scoring isn't decorative — it's structural. Without it, the loaf bursts unpredictably at weak points.
9. Bake
Dutch oven method is the standard for home ovens:
- Preheat oven to 500°F with the Dutch oven inside for at least 45 minutes
- Bake covered at 500°F for 20 minutes — the lid traps steam, keeping the crust moist so the loaf can expand
- Remove lid, reduce to 450°F, bake another 20–25 minutes until deeply browned
- Internal temperature: 205–210°F
The dark crust is not burnt. A pale sourdough crust hasn't developed full flavor. Go darker than feels comfortable.
10. Cool
Wait at least 1 hour before cutting — ideally 2. The crumb is still setting as it cools. Cutting early produces a gummy, doughy texture even if the loaf is fully baked.
Reading the Crumb
The crumb (interior texture) tells you what went right or wrong.
| Crumb | What it means |
|---|---|
| Open, irregular holes | Good fermentation, high hydration, well-developed gluten |
| Dense, uniform, tight | Under-fermented, under-proofed, or too much flour |
| Large holes at top, dense at bottom | Over-proofed — structure weakened and gas migrated up |
| Gummy, wet texture | Under-baked, or cut too soon |
| Flat with no oven spring | Dead/weak starter, over-proofed, or scored too shallow |
Failures and Fixes
| Problem | Cause | Fix |
|---|---|---|
| No oven spring, flat loaf | Weak starter, over-proofed, scored too shallow | Confirm starter doubles after feeding before using; reduce proof time; score at 30–45° angle, ½ inch deep |
| Dense crumb | Under-fermented, under-proofed, not enough gluten development | Extend bulk until dough passes jiggle/bubble signs; complete all stretch-and-fold sets |
| Gummy interior | Under-baked, cut too soon | Bake to 205–210°F internal; cool at least 1–2 hours before cutting |
| Burst on the side, not the score | Under-proofed, score too shallow or wrong angle | Proof until poke test passes; score decisively at a low angle with a sharp blade |
| Collapsed after baking | Over-proofed | Shorten proof; bake when the dough still has some spring left |
| Too sour | Over-fermented, too long cold proof, starter too acidic | Shorten bulk ferment; skip or shorten cold proof; use a liquid levain |
| Pale crust, no color | Oven not hot enough, Dutch oven not preheated | Preheat Dutch oven for 45+ min at 500°F; go darker than feels comfortable |
| Crust shatters/chips off | Humidity too low, cooling too fast | Cool on a wire rack away from drafts; don't refrigerate the baked loaf |
Notes
- Keep a baking journal for the first several loaves — note temperature, times, hydration, and results. Sourdough has too many variables to troubleshoot from memory.
- Rye flour in the starter (even 10%) accelerates fermentation and strengthens the culture — useful if your starter is sluggish.
- The same dough at 68°F and 78°F can have a 3–4 hour difference in bulk fermentation time. A probe thermometer in your kitchen matters more than most equipment.
Added Sep 3, 2026 · Updated Sep 3, 2026