The key insight most people miss: You're not adding yeast — you're cultivating wild yeast and bacteria already present in flour and air. It takes 5-7 days of daily feeding to build a stable colony strong enough to leaven bread.
Just flour, water, and patience. Whole wheat or rye flour accelerates the process (more nutrients for microbes), but all-purpose works fine.
Your starter is ready when it doubles in volume within 4-6 hours after feeding AND passes the float test: drop a spoonful in water — if it floats, the yeast is active enough to leaven bread.
Daily use: Keep at room temp, feed once daily (discard + 50g flour + 50g water).
Weekly baking: Store in fridge, feed once a week. Before baking, bring to room temp and feed 2x (12 hours apart) to reactivate.
Pro tip: Use a kitchen scale, not measuring cups — sourdough is chemistry, and weight ratios matter. A $15 scale eliminates the #1 beginner mistake (inconsistent hydration). Save your discard in a jar in the fridge — use it for pancakes, crackers, or pizza dough instead of throwing it away.
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