Sourdough maintenance: how to keep your starter strong and active

Many people think that maintaining a sourdough starter is the same as starting one. However, there is an important difference. How you feed your starter once it is active determines whether it stays strong or becomes weak and overly acidic. Because these two phases are often confused, this blog focuses specifically on maintaining a sourdough starter.

If you continue feeding your starter the same way as during the initial start-up phase, it will eventually receive too little nutrition. This results in a sour, sluggish starter with reduced leavening power. With proper maintenance, your sourdough starter will remain stable, active, and reliable.

Do you not yet have an active starter? Read the blog How to make a sourdough starter (with rye flour) first, where I explain step by step how to start a starter and when it is ready for use.

When do you start maintaining your sourdough starter?
Once your starter is active—meaning it doubles after feeding, smells fresh and slightly sour, and is full of bubbles—you can move from starting to maintaining it. This usually happens between day 6 and 10, depending on temperature, flour, and environment.

From this point on, you will:

• increase the amount of feed (adjust the feeding ratio)
• adapt maintenance to how often you bake

How often should you feed a sourdough starter?
How often you feed your starter depends on where you store it and how frequently you bake.

• At room temperature: Feed your starter 1–2 times per day
• In the refrigerator: Feed your starter about once a week. Always take the starter out of the refrigerator and let it come to room temperature before feeding. After feeding, leave it at room temperature until it becomes clearly active and approaches its peak. Only then return it to the refrigerator.

The right feeding ratio for maintenance
During the start-up phase, a 1:1:1 ratio (starter : flour : water) is commonly used. While ideal for starting a starter, it is not suitable for long-term maintenance.

Once your starter is ready for use, increase the ratio to:

• 1:3:3
• 1:5:5

The higher the proportion of flour and water: the longer it takes to reach peak activity 
the stronger and more active the starter becomes. If you want to bake quickly, feed more often or use a lower ratio. If you have more time, a higher ratio works very well. Ambient temperature (cooler in winter, warmer in summer) also affects the ideal ratio.

Preferably use:

• Lukewarm to warm water (not above ±45 °C / 113 °F, as yeast will die)
• Whole grain flour or partially rye flour for extra nutrients

If your starter seems less active, adding some rye flour can give it an extra boost.

Hygiene is essential:

• Always use a clean spoon
• Preferably work with a clean jar
• This prevents contamination and unwanted bacteria.

How much starter do you actually need?
You don’t need to keep a large amount of starter. In fact, the smaller your base, the less you have to discard. A small amount is often enough, for example:

• 10 g starter
• 50 g flour
• 50 g water

This is sufficient to keep your starter strong and allows easy scaling for baking.

What if your starter becomes less active?
If your starter seems sluggish, try the following:

• Use slightly warmer water
• Place the starter in a warmer spot
• Temporarily add some rye flour

Improvement is often visible within a few feedings.

A starter that hasn’t been fed for a long time
If your starter has been neglected, you may see a brown or grayish liquid on top. This is not mold—it’s a sign of hunger.

What to do:

• Stir the liquid back into the starter
• Place the starter at room temperature
• Give several peak-to-peak feedings

This means feeding only when the starter has reached its peak—fully risen and just before it starts to collapse. For starters normally kept in the refrigerator, always perform these feedings at room temperature.

Repeat until the starter:

• doubles quickly
• smells fresh
• is clearly active

⚠️ Never feed your starter again before it has (nearly) doubled, as this dilutes the yeast population and weakens the starter.

How to recognize an active sourdough starter
A healthy starter:

• Doubles in volume after feeding
• Contains many visible air bubbles
• Smells fresh and mildly sour
• Has a light, slightly elastic texture

When these signs are present, your starter is ready to bake with.

Finally
At Kaatjes, we’re passionate about baking bread. A well‑maintained sourdough starter is the foundation for consistent, flavorful sourdough loaves. By paying attention to feeding, timing, and temperature, your starter can stay strong and reliable for years.

Have you managed to keep your sourdough starter in good shape? Or did you run into any challenges along the way? Feel free to share your experience in the comments below — questions, doubts, and tips are always welcome. Together, we help each other grow.