On the first day, combine 30 grams of whole wheat or rye flour with 30 grams of room-temperature water in a clean glass jar. Stir until no dry flour remains.
Cover the jar loosely with a lid and leave it at room temperature for approximately 24 hours.
On the second day, keep 30 grams of the starter and discard the remainder. Add 30 grams of water and stir. Add 30 grams of flour and mix thoroughly.
Repeat this feeding every 24 hours. Keep 30 grams of starter, then add 30 grams each of water and flour.
Continue feeding the starter for 7–14 days. A temporary burst of activity followed by several quiet days is normal.
Mark the starter’s level immediately after feeding. Your starter is ready to bake with when it reliably doubles within 4–8 hours after feeding for several consecutive days.
Once established, continue feeding the starter at room temperature or store it in the refrigerator between baking days.
Notes
Cover the jar of starter with a damp kitchen towel to help maintain the moisture levels.
* Use a kitchen scale for the most consistent results.* Whole wheat or rye flour is especially helpful when beginning a starter. Once established, you may transition it to all-purpose flour or continue using whole-grain flour.* If your starter peaks and begins falling well before its next feeding, feed it every 12 hours or use 30 grams starter, 60 grams water, and 60 grams flour.* Do not cook with discard from the earliest stage of developing your starter.* Throw away the starter if you see fuzzy mold or pink, orange, or red discoloration.* The float test is not required. Reliable doubling after feeding is a better indication that the starter is ready.
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