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How to make a sourdough starter from scratch

A starter is only flour, water and time. This guide explains how it works, what to watch for and why so many first attempts fail.

What you need

  • A clean glass jar (about 500–700 ml) and a rubber band or tape to mark the level
  • Flour: wholegrain rye or whole wheat usually gets a young culture going faster than white flour
  • Lukewarm water
  • A kitchen scale: grams are more reliable than cups

Why day counts don't work

Most starters fail for one reason: people follow a day-by-day plan instead of watching the mixture. The wild yeast and bacteria are already all around you, and how fast they grow depends mostly on temperature. A stage is finished when the mixture has doubled in volume, never earlier.

Mark the starting level on the jar with a rubber band or tape. That one habit tells you more than any calendar.

What you will see

  • The first days: often little happens, or it smells odd. That is normal.
  • Then: bubbles appear, small at first and growing bigger over time, and the mixture starts to rise.
  • When it is active: it doubles in volume, is full of bubbles and smells pleasantly sour or fruity. A dome does not form yet: the young mixture is still runny and holds the gas poorly.
  • Later: the dome only appears once you keep your starter firm, as a Lievito Madre. From then on the dome test tells you when it is ready or hungry.

The most common mistakes

  • Following day counts instead of watching for the doubling
  • Leaving the jar in a cold spot: below about 20 °C everything slows down a lot
  • Giving up too early: the quiet phase at the beginning is normal
  • Closing the lid airtight: the gas needs a way out, so keep it loosely closed
The real emergencies: pink or orange streaks, fuzzy mold, or in the first days a stinging, ammonia-like smell. Throw the starter out, clean the jar thoroughly and start over. Everything else, like liquid on top, a slightly sour smell or quiet days, is fixable and usually normal.
A head start: our method begins with a simple kick-start trick using one everyday kitchen ingredient. It gets a young culture going days faster and makes the first week almost fail-proof.

The kick-start trick, the exact amounts and the complete refresh plan that takes you to a bake-ready starter: that is Module 1 of the Starter Kit.

Get the Starter Kit — $16

Frequently asked questions

How long does it take to make a starter?

Often one to two weeks until it reliably doubles after feeding. It depends on the temperature, the flour and how often you feed it.

Which flour is best?

Wholegrain rye or whole wheat flour usually starts fastest. Once the starter is active, you can keep it on white flour if you prefer.

Can I use tap water?

Usually yes. If your water smells strongly of chlorine, let it stand in an open jar for a few hours first.

Why is there liquid on top of my starter?

That is normal and harmless. It means the starter is hungry. Stir it in or pour it off, then feed.

What is the white film on my starter?

Often it is kahm yeast, which is normal and not a problem. It looks wrinkled, tight-meshed, very fine and white, and it smells of alcohol or yeast. It simply means the starter is hungry: feed it again, and at the next feeding the film is gone. Mold looks different. It is bushy or hairy, green, blue or black, forms lumpy nests and smells rotten. If it is mold, throw the starter out and start over. If you are not sure, throw it out.

Why does my starter smell like vinegar or nail polish remover?

A slightly sour smell is normal, and a sharp smell usually means a starter that is already running is hungry. Feed it and the smell becomes milder. A stinging, ammonia-like smell in the first days is different: clean the jar thoroughly and start over.

When can I bake with it?

When it reliably doubles within about 2 hours after feeding. Its full rising power then keeps growing over the next 3 to 4 weeks of regular care. Once you keep it firm, the dome test shows when it is ready.

Already have a starter? Bake your first loaf with our tested recipes.

The guides teach the basics. The kits take you all the way.

Seven step-by-step modules from first mix to first loaf. The Starter Kit is where the craft begins.

Get the Starter Kit — $16