Sourdough Starter: Building and Maintaining Your First Live Culture

If you've been thinking about baking with sourdough, starting a culture from flour and water is your first real step. It sounds mysterious, but it's really just feeding wild yeast and bacteria a steady diet so they multiply and become predictable.

This guide walks through the first week, how to keep it healthy, and when it's ready to bake with.

What You Need to Start

You don't need special equipment or ingredients. Just:

• Flour - whole wheat or rye works fastest in the beginning. Switch to bread flour or all-purpose once established.
• Water - non-chlorinated if possible. Let tap water sit out for an hour or two before use.
• A container - any food-safe jar or bowl, loosely covered.
• A scale - measuring by weight is far more reliable than volume.

A 100% hydration starter (equal parts flour and water by weight) is the standard. That means 100g flour + 100g water = 200g starter before feeding.

The First Week: Day by Day

Day 1

Mix 50g whole wheat or rye flour with 50g water in your container. Stir until no dry bits remain. Cover loosely and leave at room temperature.

That's it. You're done for the day.

Day 2

Nothing dramatic yet. Maybe some bubbles if you're lucky. If you see separation, stir it back in.

If you want to encourage activity, do a small feeding: discard half, then feed 25g starter + 25g flour + 25g water.

Day 3

This is where most starters wake up. You should see bubbles, maybe a bit of rise and fall.

Discard down to about 25g starter and feed:

• 25g starter
• 50g flour (whole wheat if you have it)
• 50g water

Mix well, cover loosely, and wait.

Day 4

Keep feeding daily. The starter should show more predictable bubbles and might rise a bit. Some bakers switch to all-purpose flour around now, others wait until day 7. Both work.

Days 5-7

By now, the starter should be reliably active. You're looking for:

• Bubbles throughout
• A slight rise after feeding
• A pleasant sour or yeasty smell
• Consistent doubling within 4-8 hours at room temperature

Continue your daily feeding schedule. When it passes these tests, it's ready to use.

Feeding and Maintenance

Once established, you have options.

Daily Feeding (Room Temperature)

If you bake regularly, keep your starter at room temperature and feed once or twice daily:

Standard feeding (1:1:1 ratio):

• 50g starter
• 50g flour
• 50g water

Mix until smooth. After feeding, your starter will:

• Drop slightly as the yeast restart activity
• Rise over 4-8 hours
• Peak when it's ready to use
• Then slowly fall again

The rising period is your window for baking. Use it when the starter is at or near its peak.

Less Frequent Feeding (Fridge Storage)

If you bake weekly or less, store your starter in the fridge and feed once a week:

1. Feed your starter as normal
2. Let it sit at room temp for an hour
3. Cover and refrigerate

When you want to use it:

• Take it out of the fridge
• Feed it (it'll wake up slowly)
• Feed it again 12 hours later
• Now it's active and ready

The fridge slows fermentation but doesn't stop it. A weekly feeding keeps it happy with minimal effort.

Knowing When It's Ready

A starter is ready to use when it reliably doubles in 4-8 hours after feeding at room temperature. It should smell pleasant and look bubbly throughout.

If your starter smells like acetone, nail polish, or vomit, it's hungry. Feed it more frequently. If it smells overwhelmingly sour, that's fine, but it might need more frequent feedings too.

A healthy starter has a tangy aroma, not a bad one. When in doubt, feed it and wait.

Troubleshooting

Starter won't rise

Common causes:

• Feeding too much flour or water at once (start with smaller feedings)
• Temperature too cold (move to a warmer spot)
• Starter just not ready yet (some take longer than 7 days)

Starter smells bad

Acetone or solvent smells mean it's starving. Feed more often.

Hairspray or nail polish remover smells are similar - more feeding.

Vomit or rotten smells in the first few days are normal. If it persists after day 7, try discarding more and feeding with fresh flour.

Mold or discoloration

If you see pink, orange, or fuzzy growth, discard everything and start over. This is rare with proper hygiene.

Hooch (liquid on top)

A clear or brownish liquid appearing on top is alcohol from the yeast. It's a sign the starter is hungry. Stir it back in or pour it off, then feed.

Moving Forward

Once your starter is active and predictable, you can start baking. Begin with simple recipes, learn how your starter behaves at room temperature, and build from there.

The most common advice I'll give: trust your starter, not the clock. Every kitchen is different. Watch how yours responds to feeding, temperature, and time. Adjust as needed.

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— C. Steward 🫑