The Complete Guide to Sourdough Bread in 2025

Sourdough bread has gone from pandemic hobby to permanent fixture in home kitchens around the world. But if you've ever pulled a dense, gummy loaf from the oven, you know it's not as simple as mixing flour and water. This guide covers everything from building your first starter to shaping a picture-perfect boule.

Building Your Starter from Scratch

A sourdough starter is a living culture of wild yeast and lactic acid bacteria. To begin, combine 50 grams of whole wheat flour with 50 grams of room-temperature water in a clean jar. Stir vigorously, cover loosely, and leave at room temperature (around 75°F / 24°C).

For the next 7–10 days, discard half the starter each morning and feed it with 50 grams of all-purpose flour and 50 grams of water. By day 5 or 6, you should see consistent bubbling and a pleasant, tangy aroma. The starter is ready to bake with when it doubles in volume within 4–6 hours of feeding.

Understanding Hydration

Hydration refers to the ratio of water to flour in your dough. A 75% hydration dough (750 grams water to 1,000 grams flour) produces an open, airy crumb with large irregular holes. Lower hydration (65–70%) is more forgiving and easier to shape, making it ideal for beginners.

As you gain confidence, experiment with higher hydration. The key is adjusting your technique — use wet hands during stretch-and-fold sessions, and don't be afraid of a sticky dough.

The Bulk Fermentation Sweet Spot

Bulk fermentation is where most of the flavor develops. At 78°F (25°C), expect 4–5 hours. At cooler temperatures, it may take 6–8 hours. Look for a 50–75% increase in volume, a domed surface, and visible bubbles along the sides of the container.

Over-fermented dough becomes slack, overly sour, and difficult to shape. Under-fermented dough yields a tight crumb and bland flavor. The "poke test" helps: press the dough gently with a floured finger. It should spring back slowly, leaving a slight indentation.

Shaping and Scoring

Pre-shape your dough into a loose round and let it rest 20–30 minutes. Then perform a final shape — pulling the dough toward you on an unfloured surface to create surface tension. Place seam-side up in a floured banneton for cold retard (12–16 hours in the fridge).

Scoring isn't just decorative — it controls where the bread expands. A single decisive slash with a lame at a 30–45° angle gives the classic "ear." Shallow cuts spread wide; deep cuts open dramatically.

Baking: Steam Is Everything

Preheat your Dutch oven at 500°F (260°C) for at least 45 minutes. The enclosed pot traps steam from the dough, enabling maximum oven spring. Bake covered for 20 minutes, then remove the lid and reduce to 450°F (230°C) for 20–25 more minutes until deeply caramelized.

Let the loaf cool completely on a wire rack — at least 1 hour — before slicing. Cutting too early releases steam and results in a gummy interior.

Troubleshooting Common Issues

• Dense crumb: Under-fermentation or starter wasn't active enough.
• Too sour: Reduce cold retard time or use a younger starter.
• Flat loaf: Weak gluten development or over-fermentation.
• Burnt bottom: Place a baking sheet on the rack below your Dutch oven.