Quick Answer
Making a sourdough starter requires only two ingredients: flour and water. Over the course of about a week, naturally occurring wild yeast and beneficial bacteria develop in the mixture, creating a living culture that can naturally leaven bread. With consistent feedings and a little patience, you'll have a healthy starter that's ready to bake with.
What Is a Sourdough Starter?
A sourdough starter is a living culture of wild yeast and beneficial bacteria that develops when flour and water are mixed together and fed regularly.
Unlike commercial yeast, a starter relies on naturally occurring microorganisms found in flour and the surrounding environment. As these microorganisms grow, they produce carbon dioxide that helps bread rise and organic acids that give sourdough its signature flavor.
If you'd like to learn more about how a starter works, read our article What Is a Sourdough Starter?
What You'll Need
Making a starter doesn't require expensive equipment.
Gather:
- Bread flour or unbleached all-purpose flour
- Whole wheat flour (optional but helpful)
- Filtered or dechlorinated water
- A clean glass jar
- A kitchen scale
- A spoon or spatula
- A rubber band or dry-erase marker
Using a kitchen scale provides the most consistent results because flour can vary significantly when measured by volume.
Day 1: Mix Your Starter
In a clean jar, combine:
- 50 grams flour
- 50 grams room-temperature water
Mix until no dry flour remains.
The consistency should resemble a thick pancake batter.
Cover the jar loosely and leave it at room temperature for 24 hours.
Don't expect much activity on the first day. The fermentation process is just beginning.
Day 2: Watch for Early Activity
You may notice:
- A few bubbles
- A slightly different aroma
- Little or no rise
This is completely normal.
Discard about half of the mixture and feed the remaining starter with:
- 50 grams flour
- 50 grams water
Cover and leave at room temperature.
Days 3–5: Keep Feeding
These are often the most confusing days for beginners.
Some starters become very active around Day 3, then suddenly seem to stop rising.
Don't panic.
This temporary slowdown is a normal part of the microbial transition as the beneficial yeast and bacteria establish themselves.
Continue feeding once every 24 hours unless your starter is becoming extremely active and hungry sooner.
Days 6–7: Look for Consistency
By the end of the first week, many starters begin showing reliable signs of health.
A healthy starter should:
- Rise noticeably after feeding
- Contain bubbles throughout
- Smell pleasantly tangy
- Reach a predictable peak before falling
Some starters are ready to bake in about a week, while others may need several more days.
Patience is one of the most important ingredients in sourdough baking.
How Do You Know It's Ready?
A starter is usually ready for baking when it:
- Nearly doubles in size after feeding
- Contains bubbles throughout
- Smells pleasantly fermented
- Reaches peak activity consistently
Rather than watching the clock, learn to recognize your starter's natural rhythm.
Common Beginner Mistakes
Expecting It to Be Ready Too Quickly
Every starter develops at its own pace.
Some become active in five days, while others need up to two weeks.
Feeding Too Frequently
Feeding before the starter has had time to ferment can slow its development.
Allow the starter to rise before feeding again.
Measuring by Cups
Using weight rather than volume provides much more consistent feedings.
A digital kitchen scale is one of the best investments a sourdough baker can make.
Throwing It Away Too Soon
Many beginners think they've failed around Day 3 or Day 4 when activity slows.
This is one of the most common—and completely normal—parts of the process.
Keep feeding consistently.
Storing It in the Refrigerator Too Early
Wait until your starter is mature and rising predictably before moving it to the refrigerator.
A young starter develops best with regular room-temperature feedings.
What If My Starter Isn't Growing?
If your starter isn't showing much activity after several days:
- Keep it in a warm location (around 70–75°F is ideal)
- Feed it consistently
- Try adding a small amount of whole wheat or rye flour
- Be patient
Most starters simply need more time.
If your starter develops mold, pink or orange streaks, or a rotten smell, discard it and begin again with a clean jar.
Megan's Baking Tip
Don't compare your Day 5 starter to someone else's on social media. Every kitchen, flour, and environment is different. Focus on steady progress rather than perfection, and let your starter teach you its own rhythm.
Frequently Asked Questions
Can I make a sourdough starter with all-purpose flour?
Yes. Unbleached all-purpose flour works well. Many bakers also add whole wheat or rye flour during the early days to encourage activity.
How long does it take to make a sourdough starter?
Many starters are ready in 7 to 10 days, although some take up to two weeks to become consistently active.
Why did my starter bubble and then stop?
This is a normal part of the fermentation process. Continue feeding it consistently, and the beneficial yeast and bacteria will become established.
Do I have to use filtered water?
Not always. If your tap water contains high levels of chlorine or chloramine, filtered water may help support healthier fermentation.
Can I bake with my starter after five days?
Some starters are ready this early, but most perform better after they develop consistent rise-and-fall cycles over several feedings.
Final Thoughts
Learning how to make a sourdough starter is the first step in a rewarding baking journey. While it may take a little patience, the process is surprisingly simple: mix flour and water, feed your starter consistently, and let nature do the work.
Once your starter becomes active and predictable, you'll have the foundation for baking delicious homemade sourdough bread for years to come.