How to rehydrate a dehydrated sourdough starter

So you've got your dehydrated sourdough starter and you're ready to bring it to life. The process is straightforward, but it does take a few days — and knowing what to expect at each stage makes a real difference. Here's exactly what to do.

What you'll need

• Your dehydrated sourdough starter (Sourdough Flakes)
• Filtered or spring water — tap water can work but filtered is better, as chlorine can inhibit fermentation
• Bakers flour (bread flour) — the higher protein content feeds the culture more effectively than plain flour
• A medium glass jar — at least 500ml capacity so the starter has room to rise
• A non-metal spoon — metal can react with the acidic culture
• A square of cloth or paper towel and a rubber band — the starter needs airflow, not an airtight lid

Day 1 — Rehydrate

Pour your Sourdough Flakes into your jar. Add 4 tablespoons of lukewarm filtered or spring water and stir well. Cover loosely with cloth and leave to dissolve for at least 60 minutes — the flakes will absorb the water and soften into a paste.

Once dissolved, stir in 30g of bread flour until well combined. The consistency should resemble a thick paste. Cover again with cloth and store on the bench at room temperature for 24 hours.

Don't be alarmed if nothing seems to be happening yet — the culture is waking up, not performing.

Day 2 — First feed

You may notice a faint sour smell and possibly a bubble or two — both good signs. Add 2 tablespoons of water and 30g of bread flour, stir well, cover, and set aside for another 24 hours.

This is a good time to name your starter. It's tradition, and bakers who name their starters tend to look after them better. Ours is called Cintra.

Day 3 — Feed again

Add 4 tablespoons of water and 60g of bread flour. Mix thoroughly, cover, and set aside. By now the consistency should start to resemble thick pancake batter and you may see small bubbles forming — this is the wild yeast and bacteria becoming active.

Days 4–6 — Building activity

Your starter is getting hungry. Feed daily with 4 tablespoons of water and 60g of bread flour, mixing well each time.

After feeding, place a rubber band around the jar at the level of the starter. Over the next few hours you should start to see it bubble, rise above the rubber band, and eventually fall back down. This rise-and-fall cycle is the key sign of a healthy, active starter.

By day five or six, most starters will be showing reliable activity. The smell should be pleasantly sour — think yoghurt or mild vinegar, not unpleasant.

Day 5–7 — The float test

When your starter looks ready, you can confirm it with the float test. Drop a small spoonful into a glass of water. If it floats, it's ready to bake with. If it sinks, give it another feed and try again in 12 hours.

The more reliable signal is doubling: if your starter consistently doubles in height within 4–6 hours of feeding and holds that height before falling, it's ready. That's your signal to bake.

Common questions

What if nothing is happening by day 3?

Don't panic. Rehydration timelines vary depending on the ambient temperature — a warmer kitchen speeds things up, a cooler one slows them down. If your kitchen is below 20°C, try moving the jar somewhere slightly warmer, like on top of the fridge or near (not on) a heating vent. Keep feeding and give it time.

There's liquid on top of my starter — is it ruined?

No. That liquid is called hooch — it's a byproduct of fermentation and a sign your starter is hungry. Pour or stir it back in, then feed as normal. Hooch just means it's time to feed sooner or increase the flour quantity slightly.

Can I use plain flour instead of bread flour?

Yes, but bread flour is better. The higher protein content gives the wild yeast and bacteria more to feed on, which produces a more active, flavourful starter. If plain is all you have, it will still work — just expect slightly slower activity.

How do I know if something has gone wrong?

A healthy starter smells sour, tangy, or slightly yeasty. If you see pink, orange, or black mould, or if the smell is genuinely unpleasant rather than just funky-sour, discard it and start fresh. With filtered water and clean equipment, this is rare.

Once your starter is active

Your rehydrated starter is now a living culture you can maintain indefinitely. Keep it in the fridge between bakes and feed it once a week. Take it out the night before you want to bake, feed it, and let it come to room temperature and peak activity before using.

For your first bake, we recommend starting with our Sourdough Bread Recipe — it's written specifically for a starter made from Sourdough Flakes and walks you through every step. If pizza is more your speed, George's Sourdough Pizza Cookbook is the place to go.

And if you haven't yet, you can find the full day-by-day rehydration guide on your Starter Guide page.