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10 daysIntermediateServes 1 active starter
French · Side

Building a Sourdough Starter from Scratch

Creating a sourdough starter requires only flour, water, and patience. By mixing equal parts by weight over the course of seven to ten days, you cultivate wild yeast and lactic acid bacteria from your environment. You will know it is ready when it consistently doubles in volume within four to six hours of feeding.

Total time
10 days
Hands-on
5 min per day
Serves
1 active starter
Difficulty
Intermediate
Before you start

Consistency is your only requirement

Use a kitchen scale for every feeding; volume measurements are too imprecise for the delicate chemistry of fermentation. Keep the jar in a warm, draft-free spot, ideally between 70°F and 75°F.

  • Digital kitchen scale
  • Glass jar with a loose-fitting lid
  • Silicone spatula
Ingredients

What goes in.

  • 50gUnbleached all-purpose or rye flour
  • 50gFiltered water (room temperature)
The key technique

Maintain the population

You must remove the majority of the starter before adding fresh flour and water. If you don't discard, the colony becomes too large to sustain itself on the available sugars, leading to a stalled fermentation.

Step by step

The method.

  1. Day 1: The Initial Mix

    Combine 50g flour and 50g water in your jar. Stir until no dry patches remain. Cover loosely and let sit at room temperature for 24 hours.

  2. Day 2: First Observation

    You may see a few small bubbles or no activity at all. Discard all but 50g of the mixture. Add 50g fresh flour and 50g water. Stir well.

  3. Days 3-7: Regular Feedings

    Repeat the discard and feeding process every 24 hours. The mixture will begin to smell slightly sour and produce more bubbles.

  4. Days 8-10: Strengthening

    Once the starter shows consistent growth, move to feeding twice a day. If it doubles in size predictably, it is ready to leaven bread.

Variations

Other turns to take.

Rye Start

Using rye flour for the first three days often jumpstarts the microbial activity due to the higher nutrient content.

Tips & troubleshooting

When it doesn't go to plan.

Tip

If the starter develops a thin layer of dark liquid on top, it is hungry; pour it off and feed immediately.

Tip

A cool kitchen will slow down the process, while a warm one will speed it up.

Tip

Use a rubber band around the outside of the jar to mark the level after feeding, making it easy to track how much it rises.

Questions

The ones that keep coming up.

Does it matter if I use tap water?

If your tap water is heavily chlorinated, let it sit out for an hour or use filtered water to avoid harming the yeast.

Can I put it in the fridge?

Only after it is fully established and active. Once stable, you can store it in the fridge and feed it once a week.

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