How to Refresh a Sourdough Starter

What a sourdough starter actually is

A sourdough starter is a fermented mix of flour and water that contains wild yeasts and bacteria. This living culture is what helps start fermentation in a new dough, giving it both rise and flavour without relying only on commercial yeast.

A starter is a living ingredient that needs a bit of care. It responds to temperature, flour, hydration, timing, and how often it is refreshed. Once you understand that, the whole process becomes much easier to follow and adapt.

The healthy side of sourdough

Sourdough fermentation can change bread in many useful ways. It can help improve flavour and texture, but it may also support things like mineral bioaccessibility, protein digestibility, and a lower post-meal glycaemic response. Longer fermentation can also help reduce certain anti-nutritional factors such as phytate, and in some cases may reduce certain FODMAPs, which is one reason some people find sourdough easier to digest than faster breads.

That is one reason sourdough also belongs in 12 Gut-Friendly Foods Worth Keeping in Your Kitchen. And if you want to build a more supportive kitchen overall, How to Build a More Gut-Friendly Plate and How to Eat More Fiber Without Digestive Discomfort both pair very well with it.

Where to get a starter

If you do not have one yet, the easiest option is often to ask someone who already bakes sourdough.

A gifted starter can be a lovely way to begin, and it also saves time. Another option is to buy one from a trusted baking source. You can also build one yourself from scratch with our Starter-from-scratch guide.

For many people, the easiest and most confidence-building start is simply to get a spoonful from someone who already has a healthy starter. That often comes with a few useful tips too.

Why people keep their starter

A sourdough starter lets you bake naturally leavened breads, buns, cakes, granola, crackers, pancakes, and more. And once you already have one, refreshing it is usually much easier than people expect.

People keep one for a few good reasons. It gives dough a natural rise, helps develop more flavour over time, and can make some breads feel easier to digest than faster, more industrial versions. It also gives you more flexibility in the kitchen, because one healthy starter can be used across many different kinds of baking.

What you need

Equipment

• a clean glass jar, such as a marmalade jar
• a lid that can sit loosely on top
• a spoon or spatula
• a digital kitchen scale
• a rubber band to mark the starting height
• hot water for cleaning the jar, spoon, and lid before use

Ingredients

• a small amount of old starter
• flour
• room-temperature water

A quick note on flour quality

Good flour does not need to be fancy, but quality does make the process easier and the result more predictable.

Organic flour can be a nice option if it fits your budget and what is available to you. And once you get more into sourdough, it can be useful to understand the differences between wheat wholemeal, wheat 1050, wheat 550, spelt wholemeal, spelt 630, rye 1150, and wholegrain rye. Flour choice changes texture, fermentation speed, flavour, and hydration, and our Guide to Flour Types for Sourdough Baking goes deeper into that.

Work clean from the beginning

Clean working matters a lot here, because it helps reduce the risk of unwanted contamination.

That is why it helps to start with a very clean jar, spoon, and lid. Rinsing or scalding them with hot water before use is a simple habit that keeps the process cleaner and more stable.

The three main styles you can refresh

The same basic idea applies to all starters, but the texture and ratios can change depending on what kind of starter you keep. In general, use the type of flour you are baking with most of the times. For instance, if you are baking most of your rye bread with the rye flour type 1150, use this one also for refreshing the rye sourdough starter.

1. Liquid rye starter

Rye starter is usually more fluid than wheat starter. You can use this starter type for baking whole flour bread or buns, for quiche dough, granola or other bake goods that are supposed to have a deeper stronger flavour.

A practical rye refresh can look like this:

• 10 g rye sourdough starter
• 50 g room-temperature water
• 50 g rye flour

If you are in Germany, rye flour 1150 is a very good choice here.

2. Liquid wheat starter

A liquid wheat starter is usually refreshed at roughly equal parts flour and water by weight.

A practical version can look like:

• 10 g wheat sourdough starter
• 50 g room-temperature water
• 50 g wheat flour

This gives you a liquid wheat starter that is easy to stir and practical for many different recipes. The German wheat flour 550 is a very good option for this type of starter.

3. Lievito madre or stiff wheat starter

Lievito madre is firmer and more dough-like. Mixing it you need to knead a little more than the other sourdough versions until it all is evenly mixed. You use lievito madre for a big variety of bake goods that are based on wheat, for instance, buns, white bread, baguette, pizza or snacks.

A practical version can look like:

• 10 g old starter
• 50 g wheat flour
• 25 to 30 g water

A stiff starter usually ferments a little differently because the lower water content slows things down, changes the texture, and often leads to a different balance of activity and flavour compared with a more liquid starter.

Step-by-step: how to refresh your starter

If you already know what you want to bake with the starter, you can calculate how much starter you need to have after refreshing. This way your starter kit isn’t too full so you don’t need to think about what to do with the rest of the active starter. On the other hand, if you are just refreshing to reactivate your starter, do it with a smaller amount of new water and flour. Always be prepared to have at least 10 g of old starter in the fridge that you can use after skipping the upper part in the jar.

Step 1. Clean the jar and tools

Start with a clean jar, spoon, and lid. Pour boiling water over all of them before you begin, so the whole process starts as clean and stable as possible.

Step 2. Add water

Add room-temperature water. Not very cold, and not hot, both versions would be too extreme for the sourdough starter. Just normal room-temperature water is enough.

Step 3. Add flour

Add the flour that matches the style you want to keep:

• rye flour for rye starter
• wheat flour for wheat starter
• less water if you want a stiffer lievito madre

Step 4. Add the old starter

For a small everyday refresh, add about 10 g of old starter to the jar. This is roughly one tablespoon, depending on the texture. Preferably, take it from the lower part of the starter, where it still looks active and bubbly. The upper part of the old starter might already be a little dry or there might be this kind of liquid that you don’t want to reuse in your refreshed version of the starter.

Step 5. Mix well

Mix until there are no dry pockets left. For a liquid starter, it should be smooth and thick. For a stiff starter, it will feel more like a paste or very small dough.

Step 6. Mark the level

Put a rubber band around the jar right after mixing. That gives you an easy visual marker for how much the starter rises.

Step 7. Cover loosely

Put the lid on top, but do not close it fully. Just place it on and turn it slightly so it stays loose.

The starter develops gas as it ferments. It needs space and a little airflow, so a tightly sealed jar is not ideal.

Step 8. Keep it out of direct sunlight

Direct sunlight can create a hotter little climate inside the jar, and that can push fermentation too fast.

The easiest solution is often to put the jar somewhere mild and out of direct sun, or loosely cover it with a towel.

Step 9. Let it ferment at room temperature

A practical room range is often somewhere around 18 to 25°C. That is a wide range, yes, but in real life most people cannot control temperature perfectly.

That is why it usually works better to watch your starter than to obsess over the exact number.

Step 10. Watch for the rise

Your refreshed starter should begin to rise, loosen, and become more bubbly.

Once it has more or less doubled, it is usually getting close to ready. A good sign is when the top is still slightly rounded upward, like a little mound. If that little dome has already collapsed, the starter has gone past its best active moment.

When is sourdough starter ready to use?

A refreshed starter is usually ready when it is bubbly, active, and has clearly risen. In many kitchens, that may happen in around 6 to 8 hours, but it can take longer depending on temperature and strength.

That is why a rubber band helps so much. It shows you:

• where the starter began
• how much it rose
• whether it is still climbing
• or whether it has already started falling

Watching the starter usually works better than the clock alone.

What to do in very warm or very cool kitchens

Temperature changes the rise speed of your starter quite a lot. In a warm kitchen, it may rise much faster and go past its peak sooner than expected. In a cooler kitchen, it may simply need more time.

If your kitchen is warmer than about 25°C, keep the jar in the coolest place you have, away from direct sunlight and hot surfaces. If needed, refresh it later in the evening or at night, or keep it in an air-conditioned room if you have one, and check it earlier than usual.

If your kitchen is cooler than about 18°C, the starter will usually move more slowly and may need more than 8 hours to rise properly. In that case, keep it in a slightly warmer spot, such as near a heater, but not right next to strong heat. The main thing is to watch the starter, not only the clock.

What if it does not rise well or not at all?

If your starter does not double within several hours, it may simply need a bit more strength. Sometimes that happens because it has been sitting too long in the fridge before the refresh.

In that case, refreshing it again for a few days in a row is often enough. Try to keep the conditions a bit more stable, use the same flour you usually use, and watch how it responds.

If it does not rise at all, something may have gone wrong with the proportions, the temperature, or the flour. That is one reason it helps to stay consistent and not change too many things at once. Check whether you used the same flour as usual, and if needed, begin the refresh again with the older starter you kept as a backup.

Keep the old starter until the new one is clearly fine

When you refresh a starter, it can be a good idea not to throw away the rest of the old one straight away. Keep it until the refreshed starter has risen well, looks active, and everything has worked as expected.

That way, if something goes wrong during the refresh, you still have a backup. Once the new starter is clearly active and you are happy with it, or once it is in the fridge and stable, you can let go of the old one.

What to do if you are not baking right away

Once your starter has been refreshed and is active, you do not have to bake immediately.

You can store it in the fridge. In the fridge, fermentation slows down a lot. It does not stop completely, but it becomes much slower. For many home bakers, a refrigerated starter is often still fine for around one week to one and a half weeks before it really wants another refresh.

If it has already been refreshed and then spends only two to three days in the fridge, it can still be active enough to use. But usually, the sooner you use it, the better.

If you already know you will not be baking that week, it can also make sense to refresh a smaller amount from the start. That way you use less flour and still keep the starter healthy and active.

How to tell whether fridge starter is still good

This is where all your senses matter. They also help you notice when your starter is still fine, and when it probably needs a refresh quite soon.

Look at it

You may see a liquid layer on top.

Start by looking at the starter carefully. A small liquid layer on top can happen, and that is often a sign that the starter is getting hungry and would benefit from a refresh soon. If that liquid is already there, do not use the part that has been sitting right in it for your next refresh if you can avoid it. Take cleaner starter from underneath instead.

If the colour has changed a lot, or you see obvious mold, fuzzy growth, or anything pink, orange, green, or strange-looking, do not keep using it.

Smell it

A healthy starter often smells pleasantly tangy, a little honey-like, earthy, or softly acidic. That kind of smell usually means it is still in a good range, even if it may soon want another refresh.

If it smells very sharp, harsh, strongly acidic, or clearly unpleasant, it has probably gone too far and should have been refreshed earlier. If it smells rotten or really off, it is better not to keep using it.

Watch how it behaves

One of the clearest signs is still how it behaves after feeding. If it wakes up, rises again, and becomes bubbly, that is a very good sign.

If it stays flat, looks weak, or hardly changes, it may need another refresh or two to come back into better shape.

A simple real-life feeding rhythm

This part matters a lot, because sourdough only becomes practical when it fits into your day.

For example, if you leave for work in the morning:

Can you change one type into another?

Yes, in many cases you can.

For example, if you only have rye starter but want to move toward wheat starter, you can refresh it with wheat flour again and again over several feeds. After a few rounds, it behaves much more like the new flour system you are maintaining.

• refresh your starter just before leaving home
• leave it at room temperature while you are out
• check it when you get home
• then either mix your dough for baking
• or move it into the fridge to bake the next day

Sourdough recipes to try

The bottom line

Refreshing and keeping a sourdough starter alive is much simpler than most people think. Use a small amount of old starter, feed it with fresh flour and water, keep it clean, let it rise, and learn to recognise when it is active and ready.

The goal is not to control every detail perfectly. It is to understand your starter well enough that sourdough baking fits into your real life and feels easy enough to come back to again and again.