Start a Sourdough Starter: A Plain Guide for Your First Week

A sourdough starter sounds like a serious commitment, and some people do treat it that way. But the thing itself is simple. It is a jar of flour and water that you feed on a schedule until the wild yeast and bacteria already living in the flour wake up and start doing the work. Once that happens, you have a living leavening that can raise your bread for years.

The first week is where most people quit, usually because they do not know what is normal. This guide is about getting you through that week with a starter that is actually alive and ready to bake.

What a Starter Actually Is

Sourdough starter is a culture. Flour naturally carries wild yeast and lactic acid bacteria on its surface and in the air around it. When you mix flour and water, you give those microbes food and a place to live. As they multiply, they produce gas, which makes the starter bubble and rise, and acids, which give sourdough its tang.

You are not making anything complicated. You are just keeping flour and water warm enough and fed often enough that the good microbes outcompete everything else.

The two things you need are simple and cheap:

• Flour. All-purpose or bread flour both work well for a starter. Whole wheat or rye get things going faster because they carry more of their bran and microbial life, but plain flour is fine.
• Water. Filtered or unchlorinated water is easiest, because chlorine can slow the culture down in the first few days. Tap water that has sat out for a day works too.

You also want a clean jar with some headroom, because the starter will grow several times its size at its peak and can push the lid off if it is too full.

The One Rule: Weigh, Do Not Scoop

From the start, weigh your ingredients in grams. A kitchen scale costs very little and removes most of the guesswork from sourdough.

A flat tablespoon of flour can vary in weight depending on how you scoop and how humid the air is. When you weigh, you get the same ratio every time, and the ratio is what keeps the starter balanced.

The standard beginner feeding is called a 1:1:1 feed, which just means equal weights of starter, flour, and water.

Your First Week, Day by Day

Do not overthink the schedule. The shape of the week looks like this:

Day 1: Mix It Up

In a clean jar, combine these by weight:

• 50 grams flour
• 50 grams water

Stir until it forms a thick, shaggy paste with no dry pockets. Cover the jar loosely, with a cloth and rubber band or a lid set on without tightening. Set it in a warmish spot out of direct sun. That is the whole start.

Days 2 and 3: Feedings Begin

The starter may do very little at first, which is normal. It is not dead, it is just getting going. Feed it once a day, around the same time.

To feed, discard most of it, then add fresh food:

• Discard all but 50 grams of starter (this is the discard, and it is useful, more on that below).
• Add 50 grams flour and 50 grams water.
• Stir, cover, and set it back in the same spot.

In the first few days you may see a burst of activity that then slows down. That first rise is usually not the good yeast yet. It is a crowd of other bacteria having a party before the balance shifts. Do not panic when it goes quiet again. Keep feeding.

Days 4 to 7: Look for the Rise

By the middle or end of the week, the starter should start to double in size a few hours after feeding, with bubbles in it and a spongy, open texture. That is the milestone you are waiting for. A starter that reliably doubles is ready to try baking with.

What the Weird Stuff Means

During the first week you will see things that look wrong. Most of them are fine.

The Liquid on Top Is Hooch, Not Rot

If you come back and find a layer of gray or dark liquid sitting on top, that is hooch. It is alcohol that the yeast produced because the starter ran out of food. It is harmless.

Hooch simply means the starter is hungry, so feed it. You can pour the hooch off or stir it in. Pouring it off keeps the flavor a little less sharp, which is why many bakers do that.

Some Smells Are Strong but Normal

In the early days the starter can smell sharp, a little like acetone or nail polish remover, or like fruit that is fermenting. That is normal as the microbes sort themselves out. It usually mellows as the culture matures. Only a smell that stays foul and rotten after several days of feeding is worth worrying about.

Kahm Yeast Is Harmless

Sometimes a thin white or wavy film forms on the surface. That is usually kahm yeast, a harmless surface yeast. It is not fuzzy. You can stir it back in or skim it off, and keep going.

When to Actually Throw It Out

The word mold gets thrown around a lot, and most of what beginners call mold is hooch or kahm. Real mold is different and worth being careful about.

Throw the starter out and start fresh if you see:

• Fuzzy growth with actual texture, especially blue-green fuzz. That is real mold, not hooch, which is always a liquid.
• Pink, orange, or red streaks or patches. These are a warning sign, and the starter should not be kept.

Everything else, gray liquid, dark spots, strong smells, a quiet first week, is usually fixable with a feeding. When in doubt about real mold, trust your eyes: liquid on top is hooch, fuzz is mold.

Do Not Throw Away the Discard

Every feeding asks you to discard some starter, and that amount adds up fast. It feels wasteful, but it does not have to be.

Keep a separate jar in the fridge for your discard. Bad discard is a lot like an unfed batter, and it is great for food that is leavened by baking powder or soda instead of the starter itself:

• Sourdough pancakes or waffles
• Flatbreads and crackers
• Muffins and quick breads
• Pizza crust and biscuit recipes made for discard

Using discard for these is one of the easiest ways to turn what feels like a chore into real food and to waste nothing from the kitchen.

Keeping It Alive Without Becoming Its Servant

Once your starter is healthy, you do not have to feed it every day forever. You have two ways to live with it:

Room Temperature: Feed Twice a Day

A starter kept on the counter needs food about every 12 hours. This is the high-maintenance way, but you get very reliable, fast-rising results. Most people who bake every day or every other day keep their starter this way.

The Fridge: Feed Once a Week

A starter lives in the cold almost like it is dormant. Keep it in the fridge and it needs attention only every one to two weeks. Pull it out a day before you want to bake, give it a feeding or two at room temperature, and it comes back to life.

The fridge method is the honest answer for most people. You get the sourdough results without being tied to a twice-daily schedule.

A Realistic Word About the First Loaf

Your first loaf may not be a picture-perfect artisan round. It might be dense, or flat, or more sour than you expected. That is normal and it is not a sign you failed. Sourdough baking is its own learning curve that comes after you have a healthy starter.

Give yourself a few bakes to find your rhythm. The goal this week is not a perfect loaf. The goal is a starter that doubles reliably and smells pleasant, because everything after that is practice.

The Short Version

• Mix equal parts flour and water by weight and feed it daily for about a week.
• Discard before each feed so the ratio stays balanced, and save the discard for pancakes and flatbreads.
• Gray liquid on top is harmless hooch. Fuzzy growth or pink streaks are real mold, and those mean start over.
• When the starter doubles a few hours after feeding, it is ready to bake with.
• Later, keep it in the fridge and feed it once a week. You do not have to feed it twice a day to keep it.

A starter is one of the cheapest long-term tools in a home kitchen: a little flour, some water, and a week of patience, and you have your own living leaven ready for a good many years of bread.

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— C. Steward 🍎