Sourdough starter looking weak, or maybe even a little (gasp!) moldy? Don’t panic! Here’s how to revive a weak sourdough starter and get it back in shape with a little time and TLC.
Once upon a time, I pulled my sourdough starter out of the refrigerator, took the lid off the jar, and paused. I knew right away something wasn’t right.
Wimpy and deflated, it didn’t have any of the bubbles that signify a healthy starter. The smell had changed from a pleasant sour scent to something different and just off. And what was that white film hovering on top? Not mold?!
For months before that, my sourdough starter lived a happy life in the door of my refrigerator. I’d pull it out every week or so, sometimes twice a week, and bake up a big batch of something yummy. After feeding it with fresh flour and water, it would go rest in the fridge door until called upon again.
But it had clearly taken a turn for the worse. I hadn’t been baking as often because life tends to happen every once in a while. It was starved, neglected, and in need of some quick intervention if I was going to save it from a sad ending in the compost pile.
I also really needed to bake and didn’t have the time to start a new sourdough starter. Since I heard you could salvage a weak sourdough starter, I was determined to try. So I went to work.
Within a day, I had a healthy sourdough starter again. It wasn’t hard to do, so if you need to revive a weak sourdough starter, here’s how.
Can You Still Use a Moldy Sourdough Starter?
Now I realize that anyone whose kitchen mantra is When in doubt, throw it out might have just suffered heart trauma because I said I was determined to save my starter. My starter that was growing some mold. That one.
We don’t save things with mold. We throw them away, and quickly.
Sort of like the bookcase we found in my basement one summer (thanks to the water games some little girls played around it unbeknownst to me).
That kind of mold we need to get rid of ASAP. But a little mold on the top of a starter may not be a death sentence.
When a sourdough starter is molding, its microbes are out of balance. Under the right conditions, though, the microbes can get back in order and the mold will disappear. Microbes are an amazingly resilient bunch of critters.
So if you’re looking at a starter with a little bit of mold floating on top, don’t panic. It’s likely savable.
However, if you’ve got mold growing through the entire starter and all over the container that stores it? Like our bookshelf, it’s too far gone. You’ll want to make a fresh sourdough starter.
Reviving a Weak Sourdough Starter Step by Step
When you need to revive a weak sourdough starter, you have a few important goals.
- Remove the mold layer from the sad starter as thoroughly as possible.
- Completely clean your sourdough jar (or whatever container you use to store your finished starter).
- Get the sourdough microbes happy again with fresh flour, water, and a little air circulation.
Here’s how to do that, step-by-step.
Step 1: Pour off or spoon out the moldy layer. It’s not crucial to remove every trace of mold, but it’s best to get out as much as possible. Once your starter has fresh flour and water, the beneficial microbes will overtake any remaining mold.
Step 2: Pour out the remaining starter from the jar into a clean measuring cup or bowl. It’s best not to scrape the sides of the jar when you do this so that you don’t add more moldy bits to the little bit of surviving starter you have, but you can scrape the bottom if you need to.
Step 3. Thoroughly wash the sourdough starter container to remove any other bits of mold with hot soapy water. Don’t worry about any dried starter that doesn’t want to wash off the sides. If you want to scrub and sanitize the jar until it’s spotless and disinfected, you can. I didn’t.
Step 4. At this point, you need to feed the remaining starter with fresh flour and water. If you have about 1/2 cup of starter left, you can give it 1 cup flour and enough water to bring it to the consistency you like. You can leave the starter in the bowl or measuring cup you poured it into for this part, or you can put it back in its now-clean jar.
Step 5. Leave it out to ferment, lightly covered with cheesecloth or a thin kitchen towel, for around 6 hours. Overnight would probably work in a pinch. If you can leave it out by an open window, that’s ideal since the extra airflow will bring in friendly microbes. If not, any room with airflow will be fine. Ideally, you’ll start to see some fermentation bubbles after this step.
Step 6: Repeat the same process with a second cup of flour and sufficient water. Leave it out for another 4-6 hours to get those microbes really active and happy again. After this stage, and if your starter is really salvageable, you should see bubbles all the way through it again.
If your starter just looks like a thin paste with no bubbles or other signs of fermentation, you probably need to make a fresh homemade sourdough starter.
Once your starter is bubbly again, consider it as good as new! You can use it just like you would have before it needed rehabilitation.
How to Prevent a Moldy, Weak Sourdough Starter
It’s a good idea to figure out why your starter molded or got really weak so it doesn’t happen again.
In my case, I was storing it in the door of the fridge (which is the warmest area of it), so I needed to feed it more often than I was. I also wasn’t baking for weeks at a time, so I also wasn’t removing much of the old starter and replacing it with fresh flour and water.
Lesson learned: keep your starter in the back of the fridge if you’re going to take a break from regular baking. If at all possible, pull it out every few weeks and replace some of the old starter with fresh flour and water, too.
Even so, my little sourdough starter fiasco gave me an opportunity to see just how forgiving sourdough baking is.
If you do let a sourdough starter get a little weak and sickly, you don’t have to despair. With just a handful of steps and a single day, you can have a healthy starter once again that smells pleasantly sour, looks perky and bubbly, and lives in the fridge without a trace of mold.
Use Your Healthy Starter in These Delicious Sourdough Recipes
And now that you have a healthy starter again, it’s time to bake! Here are some yummy recipes to get you started:
- Simple Whole Wheat Sourdough Sandwich Bread
- Healthy Whole Grain Sourdough Morning Glory Muffins
- Easy Sourdough Drop Biscuits
- Irresistible Whole Wheat Sourdough Cinnamon Rolls
- The 50+ Best Sourdough Recipes That Will Have You Baking Tonight