1. Assess Your Starter’s Current State: Before you begin, take a good look at your starter. Does it smell sour but not yeasty? Is it flat with no bubbles? Is there a layer of dark liquid (hooch) on top? These are all signs of a hungry, weak starter. If there’s mold, it’s best to discard it and start fresh. If there’s just hooch, gently pour it off or stir it in.

2. Perform a Small Refresh: Instead of feeding your entire starter, take a small amount (about 1-2 tablespoons) and transfer it to a clean jar. This helps concentrate the existing yeast and bacteria without over-diluting them. Discard the rest of the old, weak starter, or use it in discard recipes.

3. Feed with Equal Parts Flour and Water: To the small amount of starter in the clean jar, add equal parts (by weight) of fresh flour and room-temperature filtered water. For example, if you have 20 grams of starter, add 20 grams of flour and 20 grams of water. For a boost, use a mix of 80% all-purpose flour and 20% whole wheat flour.

4. Mix Thoroughly and Observe: Stir the mixture well with a spoon or spatula until there are no dry spots of flour. The consistency should be like a thick pancake batter. Scrape down the sides of the jar to keep it clean. Cover the jar loosely with a lid, plastic wrap, or a damp kitchen towel to allow air exchange but prevent it from drying out.

5. Find a Warm Spot: Place your fed starter in a warm location, ideally between 75-80 F (24-27 C). A warm spot encourages yeast activity. This could be near a sunny window (but not in direct, scorching sun), on top of your refrigerator, or in an oven with just the light on (make sure it doesn’t get too hot).

6. Repeat the Feeding Process: After 4-12 hours, observe your starter. Is it showing bubbles? Has it risen? If it’s showing signs of activity but hasn’t doubled or isn’t consistently bubbly, repeat step 3 and 4. Continue feeding every 4-12 hours (depending on its activity level) until it consistently doubles in size within 4-6 hours after feeding. This might take 1-2 days of consistent care.

7. Maintain Your Active Starter: Once your starter is consistently doubling and bubbly within 4-6 hours, it’s considered active and ready for baking. You can then resume your regular feeding schedule (daily if kept at room temperature, or once a week if stored in the refrigerator).