A sourdough starter is a living colony of wild yeast and bacteria that leavens bread without commercial yeast. It produces bread with complex, tangy flavor and chewy texture that you simply cannot get any other way. Creating your own starter from scratch is one of the most rewarding things you can do as a home baker.
The process is simple but requires patience. You are cultivating wild organisms that exist naturally on flour and in your environment. It takes about 5 to 7 days for a starter to become active enough to leaven bread, but once established, it can live indefinitely with proper care. Many bakers maintain starters that are decades old.
What Is a Sourdough Starter
A starter is a mixture of flour and water that has been colonized by wild yeast and lactic acid bacteria. When you mix flour and water and let it sit, microorganisms naturally present on the flour and in the air begin to ferment the sugars in the flour.
The wild yeast produces carbon dioxide gas that makes bread rise. The bacteria produce lactic and acetic acids that give sourdough its characteristic tangy flavor and also help preserve the bread naturally.
A healthy starter is a balanced ecosystem. It looks bubbly and active after feeding, has a pleasant sour smell, and doubles in volume within 4 to 8 hours of feeding.
Equipment Needed
You need very little to start:
- A jar: A quart-sized glass jar works well. It should be clear so you can watch the activity and tall enough to allow the starter to double.
- Flour: All-purpose or bread flour works fine. Some people use whole wheat or rye for the initial days because they contain more wild yeast and nutrients.
- Water: Filtered or bottled water is best. Chlorine in tap water can inhibit fermentation. If you use tap water, let it sit uncovered overnight to let the chlorine evaporate.
- A scale: Weighing is more accurate than measuring by volume and helps ensure consistency.
- A rubber band: Mark the jar to track how much the starter rises.
Day-by-Day Instructions
Day 1
Combine 50 grams whole wheat or rye flour with 50 grams water in your jar. Stir vigorously to incorporate air. The mixture will be thick like paste. Cover loosely (not airtight) and let sit at room temperature (ideally 70 to 80F).
Whole wheat or rye flour contains more wild yeast than white flour, which helps the starter get going. If you only have all-purpose flour, it will still work but may take a day or two longer.
Day 2
Check for any activity. You might see some bubbles, or nothing at all. Both are normal. Do nothing today. Just let it continue to ferment.
Day 3
You should see some bubbles and expansion, and the starter may smell a bit funky or like gym socks. This is normal. Do not worry if it smells bad. That will change.
Discard about half the starter (you can throw it away or use it for discard recipes). Add 50 grams flour (you can switch to all-purpose now) and 50 grams water. Stir well, mark the level with a rubber band, cover loosely, and let sit.
Day 4 and 5
Continue feeding once daily. Discard half, add 50 grams flour and 50 grams water. The starter should be getting more bubbly and should smell more pleasant, like yeast or mildly sour. It should be rising and falling between feedings.
Day 6 and 7
By now your starter should be reliably doubling in size within 4 to 8 hours of feeding. The smell should be pleasantly sour, like yogurt or beer. It will have lots of bubbles throughout.
If your starter is doubling predictably, it is ready to use for baking. If not, continue feeding once or twice daily until it does.
The Float Test
To confirm your starter is ready, do the float test. Drop a small spoonful into a glass of water. If it floats, it has enough gas to leaven bread. If it sinks, it needs more time or a feeding.
Test your starter at peak activity, which is when it has risen to its maximum height and just before it starts to fall. This is when it is most potent.
Feeding and Maintenance
Once established, your starter needs regular feeding to stay healthy. The frequency depends on where you store it.
Room Temperature Storage
If you bake frequently, keep your starter at room temperature and feed it once or twice daily. Use a 1:1:1 ratio by weight: equal parts starter, flour, and water. For example, 50 grams starter, 50 grams flour, 50 grams water.
Refrigerator Storage
If you bake less often, store your starter in the refrigerator and feed it once a week. The cold slows fermentation significantly. Before baking, take it out and give it one or two room temperature feedings to wake it up and get it active again.
What to Do with Discard
Every time you feed, you discard some starter. This feels wasteful, but it is necessary to keep the ratios right and avoid creating huge quantities of starter. Use the discard in pancakes, waffles, crackers, pizza dough, and other recipes that do not rely on the starter for leavening.
Troubleshooting Common Problems
Starter Is Not Rising
This is usually a temperature issue. Find a warmer spot (70 to 80F is ideal). Cold slows fermentation dramatically. You can also add a bit of whole wheat or rye flour to boost microbial activity.
Starter Has a Layer of Liquid on Top
This liquid is called hooch, and it means your starter is hungry. Just stir it back in and feed. The starter may need more frequent feedings or more flour per feeding.
Starter Smells Like Alcohol or Nail Polish
This is also a sign of underfeeding. The yeast has consumed all the food and is producing alcohol. Feed more often or use a higher ratio of flour to starter.
Starter Has Mold
Actual mold (fuzzy spots of black, green, or pink) means contamination. Throw it away and start over. This is rare if you use clean utensils and good flour.
Starter Is Rising but Not Doubling
Some starters are less vigorous than others. If it consistently rises but not quite doubling, try feeding with a higher ratio (like 1:2:2) or using warmer water. The bread will still work, it just might take longer to rise.
Baking with Your Starter
Once your starter is reliably active, you can use it to bake bread. The basic process is:
- Build a levain (an offshoot of your starter) with the flour type and amount your recipe calls for
- Mix the levain with more flour, water, and salt to make dough
- Ferment the dough through bulk fermentation and shaping
- Proof and bake
Sourdough bread takes longer than yeasted bread because wild yeast works more slowly than commercial yeast. Most recipes take 12 to 24 hours from start to finish. But the complex flavor and texture are absolutely worth the time.
Tips for Success
Consistency Is Key
Feed your starter at the same time each day. Use the same ratios. Consistency helps the yeast and bacteria stay in balance.
Use Your Senses
Learn to read your starter. How does it look and smell at peak activity? How long does it take to double after a feeding? This information helps you troubleshoot and know when to bake.
Be Patient
Starters go through phases. Sometimes they are sluggish, sometimes super active. Environmental factors like temperature and humidity affect them. Give it time and keep feeding regularly.
Frequently Asked Questions
Can I use all-purpose flour?
Yes. Bread flour also works well. Whole wheat and rye have more nutrients and wild yeast so they can help a starter get going, but they are not required.
My starter doubled but now it is not rising much. What happened?
Early activity is often from bacteria, not yeast. There may be a lag while the yeast colony establishes. Keep feeding and the yeast will take over.
Can I take a break from feeding?
Yes. Refrigerate your starter for up to a week (or even two) without feeding. It will smell very sour and have hooch on top, but a couple of room temperature feedings will revive it.
Can I speed up the process?
Warmer temperatures speed fermentation. You can also try adding a bit of unsweetened pineapple juice in the first few days because its acidity helps establish the right bacteria. But mostly, it just takes time.
Final Thoughts
Creating a sourdough starter from scratch is a magical process. You are cultivating wild organisms that will leaven your bread with nothing but flour and water. It requires patience but is incredibly rewarding.
Once established, your starter becomes a living part of your kitchen. With regular care, it will provide years of delicious, naturally leavened bread. Many bakers become deeply attached to their starters and bring them along when they move to a new home.
Explore more bread recipes to put your sourdough starter to work.
