Drying a sourdough starter is a common option to preserve it for a long time. A dried starter can not be used directly. It has to be reactivated first. This is how you do it.

When drying a sourdough starter the once lively microbes begin sporulating. The microbes fall asleep and hope for a better time soon. This is the reason why you can cultivate a starter from flour in the first place: The flour contains thousands of sporulated microbes. After mixing flour with water they become active again.

Fun fact - some scientists have found almost 100 million-year-old yeast spores (Jure Piskur et al. “Molecular Mechanisms in Yeast Carbon Metabolism”). If you read about scientists re-activating sourdough from Egyptian tombs - this is the reason.

Requirements

1. Dried starter
2. White flour (bread flour or all purpose flour)
3. Unchlorinated water or bottled water. Ideally warm water - roughly 25°C (77°F).
4. A jar with a lid

Step 1 (day 0)

1. Take a tiny bit of dried starter, quarter of a teaspoon is enough. If you purchased Bread Pit, you can use a third of the package.
2. Mix it with 5g of water and 1g of flour.
3. The solution will be very liquid which is desired. This allows the spores to be properly hydrated and become living microbes again.
4. Cover your jar with a lid. Mason jars are great, or Weck jars, or just a glas with a plate as a lid.
5. Place the mixture in a warm place. It will help to speed up the process. In my case I placed it in my bath-room because it was the warmest place in the house.

Step 2 (day 1)

1. Let the mixture sit for 24 hours.
2. Generously stir the mixture with a spoon.
3. Take around 5g of the mixture (very liquid) and mix with 20g of flour and 12g of water (60% hydration).
4. Discard the rest for now.

Step 3 (day 2)

1. Wait another 24 hours,
2. Take note of the smell again, it should have now started to have a slight vinegary/yogurty smell.
3. Take around 5g again of the mixture and mix one more time with 20g of flour and 12g of water (60% hydration).
4. Discard the rest for now.

Now you need to check the starter and see if it is ready to be used. Look for signs of life. Did it increase in size? Did it start to have a sour smell? Did it start to have air pockets? If yes then you can now use the mixture to inoculate the starter before baking. If not, repeat the feeding step from above, taking 5g of the starter, mixing it with 20g of flour and 12g of water. Wait another 12-24 hours and check again.

The image below shows a starter that is ready to be used. While the visual signs are important, also look for clues like the smell. It should have a slight sour smell.

Step 4 (day 3)

Take around 5g of your mixture. Mix with as much flour and water as you need to have the sufficient amount of starter you need for your recipe. My default recipe has 500g of flour, 300g of water, 100g of starter and 10g of salt. So in that case I would take 5g of my mixture, combine with 60g of flour and 36g of water. I’d roughly have 100g of starter. I’d use everything of my starter jar for the dough. I can then either take a bit of the dough after bulk fermentation to use as my next starter, or I can use the scraps from the starter jar to make a new starter. Starting now you no longer have to discard any of your starter again.

Your first sourdough bread

Yay. Your starter is active again. You never have to buy yeast again. And - you can gift some of your starter to your friends 🎉.

If you are just getting started I recommend making some flatbreads. If you would like to deep dive into wheat sourdough check out this chapter in my book. Maintenance of the starter goes a bit beyond the scope of this article. You can read more about starter maintenance here.

Happy baking! Oh and if you purchased Bread Pit, I encourage you to share some pictures of your starter with me either via email, instagram or in our community chat.

Random nerd knowledge

Fun fact - this is the reason why supermarket-dried starters always contain additional pure commercial yeast. The wild microbes take a while longer to become alive again. It would take 24-48 hours for the dough to be ready. That’s why you can not directly inoculate a dough with dried starter. The time-frame is too long and there might be unwanted fermentation initially.

I wonder if continuously drying, activating and drying could potentially make an instant dry sourdough starter? I will keep trying and report back.

Updates 4th April 2025

I changed from whole wheat to a white flour for reactivation. It seems to work better as there’s less of a risk of contamination from other microbes present in the whole flour.

Furthermore I also increased the hydration for activating the dried starter. It’s now more liquid, making mixing way easier. At the same time I lowered the amount of flour/water used to minimize waste.