How to Build a Strong Sourdough Starter from Scratch

5 min read

Baking bread at home can feel intimidating at first—I’ve been there. But with a little patience and practice, you can create bakery-quality sourdough in your own kitchen. Along the way, you may even find the process calming, and it often turns out to be more cost-effective than buying bread from the store.

I’m both a sourdough enthusiast and an analyst in the Good Housekeeping Institute Kitchen & Cooking Lab, where we’ve tested thousands of kitchen tools over the past few years—including many specialized sourdough and bread-making tools.

Unlike most breads that use commercially produced yeast, sourdough relies on a starter. After years of maintaining starters and baking dozens of loaves, here are my tips for making the process as smooth as possible.

Sourdough starter is a key ingredient in sourdough bread; it is a mixture of flour and water left to ferment at room temperature for about a week or more. During this time, it captures natural yeast from the air. With daily or twice-daily feedings of fresh flour and water, the yeast multiplies, producing beneficial bacteria and the bubbles that help bread rise.

Those bubbles are what naturally leaven your bread—no commercial yeast needed. This fermented mixture also gives sourdough its signature tang. (Fun fact: A sourdough starter is considered a living thing, so you’ll need to regularly feed and water it, much like a plant.)

Pro tip: Water is denser than flour, so 113 grams of water is about ½ cup, while 113 grams of flour takes up more space—closer to 1 cup. That’s why the cup measurements below differ, and why using a kitchen scale is the most accurate way to measure ingredients for bread baking.

Ingredients to begin (for day 1 only)

• 1 cup (113 grams) whole wheat or rye flour
• 1/2 cup (113 grams) room temperature water (some suggest bottled mineral water is best, but tap water has worked just fine for me)

Take note: Whole wheat or rye flour is often used at the start because it contains more natural yeast and nutrients, helping your starter become active more quickly. You can also use all-purpose if that’s all you have on hand. Once your starter is established, you can switch to all-purpose flour for regular feedings.

Ingredients to feed your starter (after day 1)

• 1 cup (113 grams) all purpose flour
• ½ cup (113 grams) water

Tools

• For measuring: I recommend investing in a digital kitchen scale to ensure precise amounts; traditional measuring cups and spoons could suffice.
• For storing your starter: Use a non-reactive container (glass, stainless steel, or ceramic) that holds at least 1 quart to allow for growth. If your container doesn't have a lid designed for air circulation, cover it with cheesecloth and secure it with a rubber band.
• Additional tools: I recommend a dough whisk and a sturdy set of mixing bowls. For more, check out my guide to the best tools for baking sourdough bread.

Day 1

Combine 1 cup (113 grams) of whole wheat or rye flour with ½ cup (113 grams) of water in the container you will be storing your starter in, and thoroughly mix. Leave the container out at room temperature (at least 70 degrees) for 24 hours.

Days 2 and 3

Discard half the starter (about 113 grams or ½ cup of the mixture). To the remaining starter, add 1 cup (113 grams) all-purpose flour and ½ cup (113 grams) water. Combine and let sit at room temperature for 24 hours.

Day 4

You should notice some bubbles and will want to start feeding your starter every 12 hours now. Continue feeding by weighing out 113 grams of starter, discarding the remainder, and feeding with 113 grams of all-purpose flour and 113 grams of water. Mix, cover, and let rest for 12 hours, then repeat.

Day 5

Repeat the same 1:1:1 ratio of starter, flour, and water feeding every 12 hours. By the end of Day 5, you may have an active sourdough starter.

Pro tip: If you don't want to make your starter from scratch, you can also purchase one online from companies like King Arthur Baking, which will speed up the process.

A sourdough starter is ready to use when you see lots of bubbles on the surface, and the mixture has doubled in volume. An active sourdough starter will also smell slightly fruity or tangy. You can check if your starter is ready to bake with by adding about a tablespoon of starter to a jar filled with water. If your starter floats, you are ready for baking.

After five days, if your starter hasn’t doubled in volume, isn't bubbly, and doesn't float in water, repeat the process of discarding and feeding every 12 hours until it does. The process often takes up to a week, so continue feeding for a few extra days if it hasn’t doubled yet—patience is key here.

Once you have an active sourdough starter that has doubled in volume, you can begin storing it in your refrigerator, covered, and reduce feedings to about once a week indefinitely to keep the yeast and bacteria you created fresh.

However, if you intend on baking sourdough multiple times a week you can leave your starter on your countertop and feed it daily.

Before you bake with your starter, you must revive it first. Sourdough starter cannot be used straight from the fridge.The night before you plan to bake a loaf of sourdough bread, remove the starter from the fridge, feed it with fresh flour and water, then leave it out (covered) at room temperature.

Either way, the feeding process is the same: weigh out 113 grams (½ cup) of starter and discard the rest. To the remaining mixture, add 1 cup (113 grams) all-purpose flour and ½ cup (113 grams) water. Mix and let rest, covered, until the mixture has doubled in volume. Depending on the temperature in your house and how active your starter is, this could take as little as an hour or two or up to 12 hours.

If your house is a little chilly, you can speed up the process by keeping your starter in the oven with the light on or using a sourdough incubator. Just make sure to remove your starter from the oven before turning it on.

The obvious choice is a loaf of sourdough bread, but you can also find recipes online for everything from sourdough pancakes to sourdough focaccia to sourdough pretzels.

GET THE RECIPE

Even though it’s called “discard,” you don’t have to throw it away. While it won’t leaven baked goods like an active starter, sourdough discard adds a tangy flavor and is a great way to reduce waste—I love using it for everything from crackers to pancakes. King Arthur Flour is a great resource for recipes that use sourdough starter discard.

If you have stored your starter in the fridge for a while, you may notice a clear liquid floating on top. This is hooch, a naturally occurring alcohol that is harmless. Just be sure to pour it off before using or feeding your starter.

If your starter develops mold or shows orange or pink streaks, it has gone bad and should be discarded. A foul smell—rather than the usual tangy or fruity aroma—is another sign it’s time to start over.