How To Start A Sourdough Starter From Scratch

Last Updated on September 7, 2025 by Jamie Saechao

Learn how to start a sourdough starter from scratch with this easy step-by-step recipe.  I’ve included notes on each day of feeding, the best flour to use, and frequently asked questions. 

I know that getting a started with sourdough can be intimidating.  Over the years, I have created new starters several times and used them to create delicious breads, desserts, and savory dishes. 

But, I clearly remember watching the first starter I created with a concerned eye- wondering if it would grow mold, rot, or burst into flames!

The process, however, is actually quite simple: all you need to get going is equal parts flour and water. An active sourdough starter is the key ingredient to making a lovely loaf of sourdough bread, of which I’ve now made hundreds.

And, I have not had a starter burst into flames yet….

Recently, my 6-year-old wanted to make his own starter.  And we did!

The process is straightforward and simple, though you’ll need a generous dose of patience.

Let me walk you through the simple steps.  Soon, you’ll be crafting your own wholesome homemade sourdough bread and mouth-watering sourdough cookies!

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What Is A Sourdough Starter?

Sourdough is not your typical recipe.  Think of it more as a science experiment! 

A sourdough starter is a wild culture of yeasts, water, bacteria, and flour. This combination of ingredients creates a living organism that lives on your countertop and works as yeast to allow bread to rise!  

Like pickles or sauerkraut, sourdough starter is a ferment.  One of the most remarkable aspects of a starter is that each one is unique:  it collects and reflects the particular bacteria in your home!

Sourdough is a rising agent used in specific bread recipes. It lends a distinct, tangy flavor and chewy texture beloved by sourdough enthusiasts worldwide. 

This living ingredient is full of beneficial bacteria that break down the nutrients in flour, making them easier to digest.

Unlike quick commercial yeast, the natural yeasts in sourdough starters take time to develop the bread.  

Bread takes longer to make this way, but it’s worth the wait! I regularly make delicious, wholesome breads, breakfasts, muffins, and treats with my starter.

Tools

• Clean jar (a wide mouth jar works best if you have one)
• Spatula (I like to use a thin one like this)
• Kitchen scale (for weighing in grams, optional)
• Saran wrap, lid, or other covering for your jar 
• Warm ambient temperature. Is this a tool? Maybe not, but you need to be prepared to keep your kitchen extra warm as you establish your starter.

You can also purchase a sourdough kit like this one, which has everything you need to get started.

Or, you can go budget friendly and use an old spaghetti jar (sanitized, of course).

Ingredients

• Organic Bread Flour (this recipe calls for bread flour, but you can use all-purpose flour as well)
• Filtered water

*Some people like to start their starters with rye flour or whole wheat flour, but I’ve found I can use bread flour from the get-go with great results! If you’d like to experiment with the type of flour, feel free. 

I love Organic King Arthur flour and typically use it in all of my recipes and any starter projects we have going on. 

How Long Does It Take Before Use?

It can take 10-30 days for a sourdough starter to become teeming with beneficial bacteria and ready to use.

Generally speaking, however, you can begin to bake bread around day 14.

The Importance Of Temperature

Room temperature is of utmost importance when growing a sourdough starter.  For best results, keeping a sourdough starter at 75 degrees F while it is growing is recommended.  

For our most recent experiment, however, the temperature was between 72 and 73 degrees, and our starter began to thrive within a few days. 

If your kitchen counter is not warm enough, you can put your sourdough starter on a baking sheet and put it in a cold oven, turning the light on to warm it up.  However, this should only be done for a few hours a day, not the entire day. 

How To Make Your Sourdough Starter From Scratch

Here is a step-by-step process for making a sourdough starter. I’ve made the process easy enough that a 6-year-old could do it (and my son, Malachi, did!).

Day 1: 

Pour 1/2 cup bread flour (60 grams) and 1/2 cup water (119 grams) into your jar.  

Mix well with a thin spatula or fork, scrape down the sides of the jar, and cover with your choice of lid. Let the magic work for 24 hours. 

Temperature tips:  Make sure the temperature of your kitchen is between 72-75 degrees F.

Day 2: 

If there are bubbles on top of your starter, discard half on it into the trash, then feed it 1/2 cup water and 1/2 cup bread flour.

You may or may not see a little bit of bubble action today.  If you see bubbles, discard approximately half of your starter and feed it fresh flour and water.  If no bubbles are present, leave your starter for another 24 hours. 

(Our starter had NO bubbles present, so we left it to ferment another day).  It can be normal for the liquid and solids to separate and the mixture to look flat, like this:

Day 3

It’s time to start consistently feeding your starter every day!  We are going to change the amounts slightly here. 

Discard half of your starter, and feed the remaining starter 1/2 cup flour (60 grams) and 1/4 cup water (60 grams).  Mix well, once again, with a fork or spatula.  Cover and set your starter in a warm place. 

*To discard your starter simply dump half of it in the trash. Do not dump it down the drain.

Days 4-10:

The excitement begins: you’ll likely see lots of bubbles on the top of your sourdough starter now.

Continue discarding a portion of the starter and feed it 1/2 cup of flour and 1/4 cup water each day.

I recommend waiting until your starter is two weeks old to make bread. Some people choose to start around day ten, however. There are lots of opinions on when to start, I simply think waiting a bit longer for the bacteria to establish is wise.

Make sure your starter doubles in size with every feeding before you start baking with it.

Smells + Liquids

On days 2-3, you may notice that the liquid has separated in the jar, and there may be a thin layer of brownish liquid on top of your starter.  Don’t freak out; this liquid is normal and called the “hooch.”  

It can and will develop whenever your starter gets hungry.  I rarely see hooch on my established starter because she is fed daily.  Hooch is harmless and can be stirred into the mixture or drained off the top

Your starter may also smell like paint. This is due to the naturally occurring alcohol, which is a byproduct of fermentation. 

On days 2-3, your sourdough starter may develop an unsavory smell reminiscent of dirty socks.  Have no fear; this unsavory smell can be part of the process.  It means the bacteria are changing, and it’s a good sign!

If your sourdough starter continues to have a putrid, musky gym sock smell, you will need to throw it out and start over. This has happened to me before. It doesn’t mean you can’t establish a successful starter, you just need to try again.

Feeding Ratios

I used a 50-50 feeding ratio for this sourdough starter. This means I fed the base amount of starter equal portions of flour and water, resulting in a 100% hydration starter. This formula is considered the standard feeding ratio for keeping sourdough. 

I sometimes feed my starter more flour than water to strengthen it. You can get more strengthening tips here.

Tips

• When possible, I like to check my starter at the same 24-hour mark as it grows.
• Be patient!  Growing a new starter takes time.  The time it takes to establish can vary: it can take as long as three weeks in some environments!
• Water matters! Make sure you are using a high-quality water source. Filtered water, bottled water, or spring water should all work well. Sometimes, tap water works just fine as well, but it can potentially impede the growth of your starter, so it’s better to use a filtered option.
• If growth is slow, it may be related to temperature. Make sure your home is warm enough for your starter.

When Is It Ready To Use?

Remember that sourdough is a living thing whose growth depends on its environment’s temperature, humidity, and bacteria.  Growth takes time! 

Technically speaking, a sourdough starter is ready to use after a few weeks of being fed, at least 14 days.  It takes time for the healthy bacteria to become established.

The older the starter becomes, the more beneficial bacteria and yeasts are established. With every feeding, you create a superfood that you can use to create all kinds of delicious dough!  Keep that in mind as you patiently wait for your ferment to establish!

Here are a few tale-tell signs that your homemade sourdough starter is healthy, established, and ready to be used in baked goods:

• It doubles in size within 4-8 hours after feeding.
• Float test: when a portion of the active starter is dropped into water, it should float.  I have not found this the most reliable method of testing sourdough starter readiness, but some people swear by it. 
• The starter’s consistency is loose and airy, with lots of bubbles (as shown in the photo below).
• If you are not sure if your starter is ready to use, continue discarding and feeding it.  It can take up to a month for a starter to mature. 

Ready to bake?  Get my easy sourdough bread recipe for beginners here. 

What Is Sourdough Discard?

Sourdough discard is a portion of the starter removed during daily feedings before feeding with fresh flour and water.  

Many people do not realize that a starter can exist without any discard at all!  If you feed your starter just the food and water it needs to make a bread recipe, you will not have any “leftover” discard. 

Personally, I love to keep extra discard on hand. I use it in sourdough pancakes, crepes, muffins, and my famous sourdough chocolate cake! 

Maintenance

• Regularly transfer your starter to a clean glass jar to prevent buildup and reduce the risk of mold (I do this about once a week)
• If you keep it on the counter, you’ll need to feed it frequently, at least once a day. 
• If you do not plan to bake every day, tightly cover your starter and store it in the fridge.  Pull it out a few days before you use it and start the feeding process. You’ll want to give it a few feeds before baking with it.
• Cover your starter with a glass lid or a saran wrap secured with a rubber band.  I no longer use fabric or paper towels as a cover as I believe it can encourage mold growth. 

I hope this recipe has helped you as you begin your sourdough journey. My son, Malachi (age 6), would love to share with you that the sourdough starter featured in the photos is his.

In his own words, anyone can make sourdough from scratch!