How to Make a Sourdough Starter From Scratch in 7 Days

Sourdough is the oldest form of leavened bread. Egyptian wall paintings show sourdough loaves from 1500 BCE. Before commercial yeast was isolated in the 19th century, every leavened bread was sourdough; bakers maintained a starter for years and passed it from one shop to the next. San Francisco still has bakeries using starters that have been alive since the Gold Rush. The technique you are about to follow is essentially the same one a Roman baker would recognize.

A Slice of History

Simplicity at Its Finest

A sourdough starter is two ingredients: flour and water. That is it. No commercial yeast, no sugar, no special starter pack. You combine flour and water in a jar, leave it on the counter, feed it once a day, and after a week it is a thriving culture of wild yeast and lactic acid bacteria that can leaven bread.

A Connection to Nature

The yeasts that leaven a sourdough starter come from two places: the flour itself (microbes survive milling) and the air around your kitchen. Each kitchen has a slightly different microbiome, so each sourdough starter develops its own flavor profile over time. A starter raised in Denver tastes different from one raised in Portland or Charleston. Once you have a starter, it carries the signature of your kitchen.

Superior Flavor and Nutrition

Sourdough bread tastes more complex than yeast bread. The lactic acid bacteria produce flavor compounds (acetic and lactic acid, plus dozens of other esters) that develop slowly during the long fermentation. The same long fermentation also breaks down some of the gluten, which makes sourdough easier to digest for many people, and improves the bioavailability of minerals like iron and zinc by reducing phytic acid in the flour.

Creative Expression

Once you have a starter, the possibilities open. Bread is just the beginning. Sourdough pancakes, English muffins, pizza dough, focaccia, crackers, pretzels, even waffles all take the same starter. Each ferments differently and shows off the starter’s character.

A Lesson in Patience

Sourdough teaches a different relationship with time. You cannot rush it. The bread is ready when it is ready, not when you want it. Most home bakers who stick with sourdough find this both the hardest and the most rewarding part of the craft.

How to Make Sourdough Starter From Scratch

Total time: 5 to 7 days. Active time: about 5 minutes a day.

What you need:

• All-purpose flour or bread flour (whole wheat or rye accelerates fermentation if you have some)
• Filtered water (chlorinated tap water can stall fermentation)
• A clean quart-size glass jar with a loose-fitting lid
• A kitchen scale (grams; volume measurements are unreliable)
• A rubber band or marker to track the level

Daily routine:

1. Day 1. Combine 50g flour and 50g filtered water in the jar. Stir well. Cover loosely. Let sit at room temperature (70-75°F) for 24 hours.
2. Day 2. You may see small bubbles. Add 50g flour and 50g water. Stir. Cover loosely.
3. Day 3. The starter should smell mildly fruity, possibly cheesy. Discard half of the starter (this is important; it keeps the culture from getting overwhelmed by acid). Feed the remaining starter with 50g flour and 50g water. Stir.
4. Day 4. Bubbles increase. Discard half. Feed 50g flour and 50g water. By now, the starter may rise noticeably between feedings.
5. Day 5. Discard half. Feed 50g flour and 50g water. The smell should be tangy, almost sour beer. The starter should roughly double in size between feedings.
6. Day 6. Same routine. The starter is approaching readiness.
7. Day 7. The starter is ready when it doubles in size within 4-6 hours of feeding, has a tangy sour smell, and is full of bubbles. If those three criteria are met, you have an active starter ready for baking.

Want It Even Faster?

Adding a small amount of whole wheat or rye flour to the all-purpose mix at the start accelerates fermentation by about a day. These flours hold more wild yeast on the grain. Use 25g whole wheat plus 25g all-purpose on day 1, then switch to all-purpose from day 3 onward.

Frequently Asked Questions

Why do I have to discard half of the starter? Without discarding, the starter gets overwhelmed by acid and the yeast cannot keep up. Discarding refreshes the food-to-microbe ratio and keeps fermentation strong.

What do I do with the discard? Sourdough discard is great in pancakes, crackers, pizza dough, and English muffins. Search any of those terms plus “sourdough discard” for recipes.

How do I keep it long-term? Once active, transfer to the fridge and feed once a week. Take out 24 hours before baking and feed at room temperature.

What if there is liquid on top? The dark liquid is called “hooch.” It means the starter is hungry. Stir it back in or pour off and feed.

Simple Sourdough Bread Recipe

Ingredients:

• 100g active sourdough starter
• 375g filtered water
• 500g bread flour
• 10g kosher salt

Instructions:

1. Mix starter, water, flour, and salt in a large bowl. Mix until no dry flour remains.
2. Cover and rest 30 minutes.
3. Stretch and fold the dough in the bowl (lift a corner, stretch up, fold over) every 30 minutes for 2-3 hours.
4. Shape into a round or oval loaf. Place in a floured banneton or bowl lined with a floured towel.
5. Cover and refrigerate overnight (12-18 hours).
6. Preheat oven to 500°F with a Dutch oven inside, 30 minutes.
7. Turn the dough into the hot Dutch oven, score the top, cover, and bake 20 minutes.
8. Remove the lid, reduce heat to 450°F, and bake another 20-25 minutes until deep golden brown.
9. Cool 1 hour before slicing.

Get the Full 2026 Farmers’ Almanac

All-Access members get the full 2026 Almanac, planting calendar, Best Days for cooking and food prep, and 200 years of weather wisdom in one searchable archive.

Join All-Access