Everything You Need to Know About Making a Sourdough Starter From Scratch—Including the Best Flour to Use

A colony of bacteria and wild yeast, a live starter creates the leavening needed to bake a loaf of bread.

sourdough starter
Photo: Getty Images / alvarez

Making the perfect loaf of sourdough bread is an accomplishment many home bakers strive for. These breads, with their burnished, dark crusts and chewy crumbs, were made with a live starter— an active colony of wild yeast formed by continuously combining flour and water until it is bubbly enough to create the leavening needed to bake a loaf of bread.

This way of raising dough is what people used long before commercial yeast was developed. When that arrived, it made baking more consistent and convenient. But there's something about the digestibility of eating naturally leavened breads that makes creating sourdough starter from scratch worth the extra work. While you can certainly get a homemade starter from a friend (or mail-order one), it's also possible to make one on your own.

Sourdough Starter, Explained

A sourdough starter is a symbiotic colony of bacteria and wild yeast. "The organisms cohabitate well—subsisting on what we feed them (flour and water) and producing gas and other by-products which flavor and raise our bread and other baked goods," says Martin Philip, baking ambassador for the King Arthur Baking Company and author of Breaking Bread: A Baker's Journey Home in 75 Recipes.

Making a sourdough starter takes about one week. The process begins by stirring together equal amounts of flour and water in a jar and letting the resulting paste sit in a warm room; you should then stir and feed at regular intervals.

Recommended Flours

Philip says the best starting material is a wholegrain flour. "I recommend whole rye, as it contains significant vitamins and minerals and ferments well," he says. Also note that you should never use bleached flour when making a sourdough starter from scratch. A blend of white flour, like All-Purpose, with a whole grain wheat or rye will give a more complex flavor to your dough; those whole flours also have more microbial content for the yeasts to feed upon.

Choosing a Container

A variety of vessels will work for initiating a starter as long as they come with a lid, according to Philip, who says you can use anything from glass to nonreactive metal bowls or even a repurposed plastic container.

However, if you want to better see the activity of your starter, consider selecting a vessel that is clear. More important than the type of container is its size—you should choose one that is big enough for your starter to double in mass.


It's important to feed your starter with water that is about 80 degrees—too hot and it could kill the yeast. Also, an ambient temperature of about 70 to 75 degrees is ideal for encouraging activity in your culture. If your kitchen is cool, place the starter in the oven with only the oven light on, in a warm corner cupboard, or on a shelf near an electronic device that gives off a small amount of heat.


Peter Reinhart, author of The BreadBaker's Apprentice, suggests stirring your starter two to three times daily for about one minute each time to aerate it. You should only do this during the first week of establishing your starter—it's not necessary once you've developed a stable culture.

"Yeast loves oxygen and multiplies faster when you stimulate the mixture with air," he says. "In addition, the stirring evens out the hydration of the dough and exposes any surface organisms that may have drifted onto the starter to the acidic environment within, and thus deactivates them while the yeast and the good lactobacillus organisms continue to grow."

Feeding Your Starter

Once you've created a stable culture, you'll need to feed your sourdough starter in order to keep it alive. Kierin Baldwin, chef-instructor of Pastry and Baking Arts at the Institute of Culinary Education, says how frequently you feed your starter (which you do by adding flour and water to the culture) depends on when you are going to be using it.

"When I am planning to bake bread, I usually feed my starter two to three times per day for a couple days before I use it," he says. "When I'm not going to be baking, I usually keep my starter in the fridge and only feed it once every few weeks." Baldwin adds that the starter should rise to its full height each time before you feed it again.

How to Make Sourdough Starter

Now that you know the basics, you're ready to make our Sourdough Starter recipe. To do so, you'll only need two ingredients, plus water.


  • 100 grams organic rye flour
  • 200 grams unbleached organic all-purpose or bread flour, plus more for feeding
  • Lukewarm water


  1. Mix together both flours. Measure 45 grams flour mixture (about 1/4 cup), setting the rest aside. Place in a bowl or container (we use a quart takeout container, so it's easy to watch grow). Add a scant 1/4 cup lukewarm water (45 grams) and mix until it creates a thick batter. Keep at room temperature, covered with a kitchen towel.
  2. Repeat feedings of 45 grams each water and flour mixture once a day at the same time, mixing with a rubber spatula, for 4 days. In the beginning you won't notice much movement; by the end, the starter should appear lively, with a bubbly appearance.
  3. On the fifth day, switch to entirely white flour and water, and start feeding twice—once in the morning and once at night. (At first you may smell some strong, not-very-pleasant smells, but eventually the starter will smell nutty and a little sour but pleasant.) Once it ferments—predictably rises, doubling in volume and creating a porous, webby-looking mixture after feedings—it is ready to use; this took us about 7 days. From this point, refrigerate your starter completely covered with the container lid.
  4. Start a regular feeding schedule—at least once or twice a week. For each feed, to maintain a large starter, remove all but 100 grams (discard the rest, or use for another purpose, such as our banana bread and cookies recipe), and add 100 grams each all-purpose flour and water.
  5. To maintain a smaller starter, remove 40 grams (discarding or using the rest), and feed with 40 grams each all-purpose flour and water. In the latter case, you may need to build your starter up to have amounts you'll need for recipes with leftover to maintain it; just feed without discarding for a couple of days in advance of when you'll need it.
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