How to revive a dried sourdough starter

Dried sourdough starter is the closest thing a starter has to hibernation. Spread thin, dried and sealed in a jar, it can wait for years. Maybe you dried some as a backup, or a friend gave you a bag of flakes. Either way, waking it up takes a few days and a warm spot. Here's how, following King Arthur Baking's method.

Before you start

• Use a clean jar of at least a pint (about 475 ml), with a loose-fitting lid. Fermentation makes gas, so don't seal it tight.
• Find a warm spot. Warmth matters more than anything else here. King Arthur's baker used an oven with only the light switched on, at about 85–90°F (29–32°C). A spot around 75–80°F (24–27°C) works too, just more slowly. In a cool kitchen, everything takes longer.
• Weigh things if you can. The amounts below are by weight.

Step by step

1. Rehydrate. Put the dried starter in the jar with twice its weight in lukewarm water, around 80°F (27°C), not hot. King Arthur's example is 1 oz (28 g) of dried starter to 2 oz (57 g) of water. Stir now and then. The flakes take about three hours to dissolve.

2. Add the first flour. Stir in flour equal to the weight of the dried starter you began with, 1 oz (28 g) in the example. All-purpose flour works. Cover loosely and leave it somewhere warm.

3. Wait about 24 hours. At around 85°F you should see some bubbles by now. In a cooler kitchen it can take longer, and seeing nothing yet is still normal.

4. Feed without discarding. Add flour and water, each equal to the weight of the dried starter you started with, 1 oz (28 g) of each in the example. Don't throw anything away yet. King Arthur's baker saw strong bubbling about eight hours after this feeding.

5. Feed again the same way. Still no discarding. About twelve hours later it should have expanded. Rising and then falling back is normal. It means the starter is eating.

6. Switch to normal feedings. Once it's clearly active, start discarding. King Arthur's example keeps 4 oz (113 g) of starter and feeds it 4 oz each of flour and water, and at that point it tripled in four hours. From here, feed it like any other starter. A 1:1:1 feeding, such as 50 g starter, 50 g flour and 50 g water, once or twice a day, is a good rhythm.

How long does it take?

Following King Arthur's timings at about 85°F, the steps add up to roughly two days. At ordinary room temperature, give it longer. Colorado State University Extension describes revival as taking several days of regular feeding. A cool kitchen just means a slower start, not a failure.

How to tell it's ready to bake

Bubbles alone aren't enough. A revived starter is ready when it doubles within about 6 to 8 hours of a feeding at 75°F (24°C) or warmer, and does it again on the next feeding. Some starters get there in a couple of days. Others take longer, so keep feeding daily. Use a rubber band around the jar at the starting level to make the rise easy to see.

When to stop and start over

Throw it out and start again with a clean jar if you see:

• mold, any fuzzy growth;
• a pink or orange tint or streaks;
• a putrid, rotten smell.

That's contamination, not slow progress. A sour or alcohol smell, on the other hand, is fine. See what your starter's smell means.

If you've fed it daily for several days and seen no bubbles and no rise at all, the dried starter may not have survived. Because dried starter keeps so well, it's worth simply starting again with more flakes if you have them.

Storing dried starter

Keep dried starter in an airtight glass jar in a cool, dark place. It doesn't need the fridge. University of Illinois Extension also recommends keeping it airtight and away from sunlight and heat.

Do it with a guide in your pocket

Sourdough Starter Tracker has a 7-day guide for exactly this. Choose From dried when you add a starter, and the app walks you through each day with what to do and what to expect, following King Arthur's method and university extension guidance. It's spread over a week because most kitchens are cooler than 85°F. Feeding reminders keep you on track, and the starter's card shows From dried so you always know which jar is which. When it's back to full strength, the app marks the moment in that starter's story.

Sources

• King Arthur Baking: Putting your sourdough starter on hold, Do you think you killed your sourdough starter?, Why is my sourdough starter not rising?
• Colorado State University Extension: Sourdough starter best practices
• University of Illinois Extension: Sourdough 101