1. Prepare Your Container: Start with a clean, large glass jar. A 1-quart size is ideal, as your starter will grow. Ensure it’s spotless to prevent unwanted bacteria from interfering with your wild yeasts.

2. Combine Initial Ingredients: In your clean jar, combine 50 grams (about 1/4 cup) of whole wheat flour or rye flour with 50 grams (about 1/4 cup) of filtered, room-temperature water. Mix thoroughly with a spoon until there are no dry spots and the mixture forms a thick paste. This initial boost from whole grain flour provides a rich food source for wild yeasts.

3. Cover and Rest: Loosely cover the jar. A piece of cheesecloth secured with a rubber band, a coffee filter, or even a loose-fitting lid works perfectly. The goal is to allow air circulation while preventing contaminants. Place the jar in a warm spot, ideally between 70-78 F (21-26 C), away from direct sunlight.

4. First 24-Hour Observation: After 24 hours, you might see a few tiny bubbles or no activity at all. This is normal. The wild yeasts are just beginning to wake up and multiply.

5. The First Feeding (Day 2): Discard about half of your starter (around 50 grams). To the remaining 50 grams of starter, add 50 grams of all-purpose flour and 50 grams of filtered water. Mix well until smooth. Cover and return to your warm spot. Discarding half ensures there’s enough food for the remaining yeasts to thrive and prevents the starter from getting too large.

6. Continue Daily Feedings (Days 3-7+): Repeat the feeding process every 24 hours: discard half, then feed with equal parts flour and water. You should start to see more consistent activity – bubbles, a slight rise, and a pleasant, tangy aroma. If using a rubber band around the jar at the starter’s level, you can visually track its growth.

7. Transition to Twice-Daily Feedings (Optional): Once your starter is consistently doubling in size within 6-8 hours after feeding, you can transition to feeding it twice a day, every 12 hours, using the same discard-and-feed method. This helps to strengthen it further.

8. Ready for Baking: Your starter is ready when it consistently doubles or triples in size within 4-8 hours after feeding, has many visible bubbles, and smells pleasantly sour, like ripe fruit or yogurt. It should also pass the “float test”: drop a small spoonful into a glass of water; if it floats, it’s ready to bake with!