How to Make Sourdough Starter - Home Grown Happiness

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This guide shows exactly how to make a sourdough starter from scratch. Once you understand the process, it’s simple, and it just takes a little time and patience. If you’re troubleshooting, check out my Sourdough Bread Troubleshooting Guide or my post on maintaining a sourdough starter.

A hand lifts the lid off a glass jar filled with sourdough starter set on a light, speckled surface.

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A sourdough starter

A sourdough starter is the foundation of homemade sourdough bread, English muffins, and rolls. It’s a living mixture of wild yeast and bacteria that feed on flour and water. Over time, they form a healthy colony that makes your bread rise without any commercial yeast.

When you first create a starter, you encourage these wild organisms to grow by giving them fresh flour and water every day. Once established, the wild yeast produces carbon dioxide that lifts your dough, while the natural bacteria add that signature tangy flavour.

The bacteria, mainly lactobacilli, produce lactic and acetic acids. This is what gives sourdough its sour flavour.

A glass jar filled with bubbly, creamy sourdough starter—perfect for anyone learning how to make sourdough starter—sits on a light, textured surface with a soft, neutral background.

What you need

Every starter develops a little differently depending on your room temperature, humidity, and even the flour you use.

You’ll need:

Flour
Water
A kitchen scale

It’s best to measure by weight for consistency.

Choosing the flour

Any grain-based flour can work, but unbleached all-purpose or bread flour gives the most consistent results. Rye and whole wheat can be used too, though rye tends to ferment faster because it contains more natural sugars and enzymes.

Rye flour often makes a starter look active early on, but that early bubbling can be misleading. It’s mostly bacterial activity before the yeast really establishes itself. Even if your starter looks bubbly after a day or two, it’s still too young to bake with. A white flour starter can later be used to bake whole grain or rye breads, so it’s a good all-purpose base.

Choosing the water

If your tap water is heavily chlorinated, it can slow fermentation. Filtered water, or tap water that has been boiled and cooled, works best.

Personally, I just use tap water. Mine doesn’t affect my starter or other ferments. If you’re unsure about yours, filtered water is a safe choice.

The best temperature for a sourdough starter

Yeast and bacteria grow best at around 21-26 °C (70-79 °F). If it’s too cold, the process slows right down. In very warm conditions, it will speed up, and your starter may need more frequent feeds.

Cooler temperature tip:

Pop your starter in a cooler bag with a jar of hot water beside it and close the bag to keep the warmth in. It’s a great little warm space for cold winter days. A yoghurt maker also works well. Fill it with a little bit of hot water (making sure it doesn’t touch the starter jar or it can get too hot) and set the starter jar inside so it stays gently warm.

Day-by-day sourdough starter guide

Day 1

The following uses 30 g flour and 30 g water as a base.

Note: I always mix the flour, water, and starter in a separate bowl first, then scrape the smooth mixture into a clean jar. It keeps the jar tidy and makes level markers easy to see. Old starter sticks like glue, so this saves a lot of scrubbing.

A person stirs flour and liquid together in a small bowl with a black spatula on a textured light-colored surface, demonstrating how to make sourdough starter.

Mix flour and water in a bowl until combined.

A hand holds a small glass bowl containing a creamy white substance, possibly yogurt or whipped cream, against a light, speckled background—perfect for those curious about how to make sourdough starter from scratch.

Put in a clean jar and cover with a balanced lid or cloth.

Day 2

Tip the starter into a bowl, add 30 g flour and 30 g water, and mix until smooth. Then transfer it to a clean jar.

Day 3

You might notice bubbles forming after day 2, but this early activity comes from bacteria, not yeast. It’s a good sign that fermentation has started, but your starter still needs more time before it’s ready to bake with.

An open glass jar filled with sourdough starter sits on a speckled countertop, reminiscent of jars often used for how to make sourdough starter. The white lid rests nearby on the right side. — The morning of day 3 of a new starter. Plenty of bubbles from bacterial activity.

A small glass jar filled with creamy, light beige sourdough starter—a perfect visual for anyone curious about how to make sourdough starter—rests on a textured surface, the background softly blurred. — The bubbles are not from yeast yet though, so the starter needs more time before baking with.

Pour 30 g of your starter mixture into a new bowl, feed it 30 g of flour and 30 g of water, mix well, then transfer it to a clean jar. Mark the level with a rubber band so you can see how much it rises. Discard the rest.

Days 4–10:

Repeat the same feeding each day: take 30 g of starter, feed it 30 g flour and 30 g water, and move it to a clean jar. Continue discarding the excess.

By day 4 or 5, you should see more bubbles or smell a mild tang. That’s a good sign, though it’s still not ready for bread. You can use some of the discard for recipes like pancakes or cookies.

Discarding is important. It keeps the yeast and bacteria balanced by giving them enough food each time you feed. If you keep feeding the entire jar, it compounds quickly and you’ll burn through a lot of flour.

Keep only a small portion (about 30 g) and feed that each day. Save the rest of your discard in a container for sourdough discard recipes.

A clear glass jar partially filled with creamy, bubbly sourdough starter sits on a light, textured surface—an essential step in learning how to make sourdough starter. A brown rubber band is wrapped around the jar.

Things to watch for

If your starter becomes runny, it’s usually because of the acid and alcohol produced by the bacteria and yeast. That’s normal. Just keep feeding it.

If liquid forms on top or underneath, it’s a sign your starter is hungry. Check the temperature. If it’s too hot, fermentation speeds up. Feed more often, every 12 hours if needed, until it settles.

Feeding ratio

While building your starter, use a 1:1:1 ratio which is equal parts starter, flour, and water by weight. Measuring by weight keeps your starter consistent, as water weighs more than flour.

If your starter is doubling within 6 hours by day 6 or 7, it’s nearly ready. Keep feeding 1:1:1 twice daily until it becomes strong and predictable.

Testing your starter’s strength

To check if your starter is ready to bake with, it should double after feeding it at 1:1:1 within about 4-5 hours at room temperature, 21-26 °C (70-79 °F).

You can also test it by feeding it a higher ratio, like 1:2:2 (one part starter, two parts flour, two parts water). If it can double or triple within 6 hours, it’s strong enough to raise a loaf.

If it’s still slow, keep feeding twice daily for a few more days and test again.

Maintaining your new starter

Once your starter is active and reliable, regular maintenance keeps it strong. Feed it often enough to avoid acid build-up. If you’re keeping it at room temperature, feed 2-3 times a day at 1:1:1, or twice a day at 1:2:2. In warmer weather, you may need to feed more frequently.

When it peaks (meaning it has doubled and just before it starts to fall) that’s when it’s best to use it for baking.

Once it’s well established, you can store it in the fridge. For more details, see my full guide on how to maintain a sourdough starter.

Sourdough starter troubleshooting FAQs

The sourdough starter is frothy but not rising

Chances are it was the lactobacillus bacteria in your starter forming those bubbles, and not the yeasts. Bacteria also create bubbles while they are converting sugars to lactic and acetic acid, but it’s the yeasts in the starter that will give rise to your bread. The yeast colony takes a little longer to establish itself. Be patient and keep feeding and refreshing your starter

Sourdough starter not bubbling.

Be patient and keep regularly feeding your starter and ensure it’s in a warm spot. If you’ve been feeding your starter for at least 6 days and it’s not bubbling you could experiment with an extra feeding, or check your water source and that it’s not hindering the starter.

My starter has water forming on the top.

This is a sign that your starter is hungry. Your starter might be fermenting a little too fast and the yeasts have run out of food. This can happen if the room your starter is in is too hot.
Check the temperature and fix it if it’s too hot before continuing. Then, carry on with the 1:1:1 feeds, but you can switch to 12 hourly feeds if it keeps splitting.

My starter rose really high and then it fell right back down.

It is normal for a starter to rise, reach its peak, and collapse once it has run out of food. Once your starter can double within 5-6 hours after being fed 1:1:1, switch to 12 hourly feedings.
If it doubles within 4-5 hours with the increased feedings, try the starter activeness test.

My starter used to double in 6 hours and now it’s taking much longer.

Has the temperature changed? If it’s colder your starter will take longer to double. Have you increased the feedings? If you increase the feeds before the starter is ready, it will slow things down a bit.

Will my starter grow mold or get bad bacteria in it?

If you keep up with regular discarding and feeding, in a fresh jar each time, your lactobacillus colony will thrive. As they do, the amount of lactic acid they produce will inhibit mould growth and harmful bacteria.
A contaminated sourdough starter is pretty rare. If you do see mould growing on your starter or it develops a pink, red, or orange tinge, discard it and start again.

Sourdough Starter Recipe

Elien Lewis

A sourdough starter recipe to make your own simple sourdough starter + how to maintain it

4.73 from 104 votes

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Additional Time 10

Total Time 10

Ingredients

Unbleached all-purpose flour
Water*