How to Feed a Sourdough Starter: The Complete Maintenance Guide

You have done the hard work of creating a sourdough starter from scratch, and now it sits in a jar on your counter, bubbling with life. Keeping it that way — active, healthy, and reliably leavening your bread — requires consistent care through regular feedings. Feeding a sourdough starter is not complicated, but understanding the why behind the process makes you a much better caretaker of your culture and a more confident baker overall.

Why Sourdough Starters Need to Be Fed

A sourdough starter is a living ecosystem of wild yeast and lactic acid bacteria. These organisms consume the sugars in flour as their food source, producing carbon dioxide (which makes bread rise), alcohol, and organic acids (which contribute flavor and preservation). Once all the available food is consumed, the organisms begin to struggle — the pH drops as acids accumulate, yeast activity decreases, and the starter enters a dormant state. Left too long without food, harmful compounds build up and the starter can die. Feeding replenishes the food supply, maintains a stable pH environment, and keeps the microbial population thriving.

The Basic Feeding Process

Feeding a sourdough starter is simple: discard a portion of the existing starter, then add fresh flour and water. The discard step is essential — without it, the cumulative acidity would overwhelm the yeast's ability to function, and the volume would grow unmanageable. Here is the standard feeding method:

• Discard all but 50g of your starter (or less if you maintain a smaller culture)
• Add 50g of fresh flour — all-purpose, bread flour, or a blend with whole wheat
• Add 50g of room-temperature, non-chlorinated water
• Stir vigorously until completely combined — no dry flour remaining
• Mark the new level with a rubber band or tape to track how much it rises
• Cover loosely and leave at room temperature until it peaks (doubles and begins to recede)

This 1:1:1 ratio (starter:flour:water by weight) is the standard starting point. You can adjust the ratio to control how quickly your starter peaks — a higher ratio of fresh flour (1:2:2 or 1:5:5) extends the time to peak activity, useful for timing your starter to be ready for an evening or morning bake.

Feeding Schedules: Counter vs. Refrigerator

How often you feed your starter depends entirely on how you store it. A starter kept at room temperature (68–75°F / 20–24°C) is active and hungry — it typically needs feeding once or twice daily depending on room temperature and feeding ratio. In warmer weather, the starter ferments faster and may need feeding twice daily to prevent it from over-fermenting and developing an unpleasantly sharp flavor.

For most home bakers who do not bake every day, refrigerating the starter between baking sessions is far more practical. In the refrigerator, fermentation slows dramatically, and weekly feedings are sufficient to keep the starter healthy. To bake with a refrigerated starter: take it out the night before baking, feed it, leave it at room temperature overnight, and it should be at or near peak activity by morning, ready to mix into your dough.

Signs of a Healthy vs. Struggling Starter

Reading your starter is a skill that develops over time and makes you a much more confident baker. A healthy starter at peak activity will have doubled (or more) in size since feeding, will have a domed or slightly domed top, will be full of bubbles throughout the culture when you stir or look at its sides through a glass jar, and will smell pleasantly sour — like yogurt, mild vinegar, or apple cider. The float test (dropping a small spoonful into water to see if it floats) is a rough indicator of activity but not perfectly reliable — rely primarily on visual and smell cues.

A starter that smells strongly of acetone or nail polish remover is simply hungry — feed it immediately and consider twice-daily feedings for a few days. A starter with a layer of grey or dark liquid (called "hooch") on the surface is also just very hungry — pour off the liquid and feed right away. Pink or orange streaks indicate contamination and the safest course is to discard and start fresh.

Consistent feeding is the foundation of great sourdough baking. Once you develop a rhythm with your starter — understanding its personality, how it responds to temperature and flour type, and how to time it for your baking schedule — you will have a reliable partner in the kitchen that opens the door to an entire world of naturally leavened breads and baked goods.