How to Store a Sourdough Starter in the Fridge (and Wake It Back Up)

When I first started baking with sourdough, my starter lived on the counter and I fed it every day or two, religiously. I also had so much discard, more than I could ever use. So I did some research and learned about the refrigerator, and it changed how much sourdough fits into a regular week.

A starter that lives in the fridge asks for a lot less of you. If you bake once a week or less, or you're traveling, or you simply want a break from the daily feeding, this is the setup I'd point you toward. Here's exactly how I store mine, how I wake it up, and what to do when it's been in there longer than it should have been.

What the fridge actually does

Cold slows everything down. The yeast and bacteria in your starter are still in there, but they're eating so slowly that a jar can go a week or two between feedings instead of needing food every day. It also protects you from your own busy schedule. A starter that gets neglected on the counter can grow mold. A starter that gets neglected in the fridge has a much longer runway before that happens.

If you plan to bake often, the counter is still a good home, and I do think my loaves were slightly better when my starter lived out there. The fridge is the choice for people who bake once a week or less, which is where I am these days. If you're not sure which camp you're in, my guide to feeding a starter walks through the counter version too.

How I put a starter into the fridge

The move is simple. Feed your starter, then put it back in the fridge until the next bake.

My feeding is 30 grams of starter, 100 grams of water, and 100 grams of flour (70 grams bread flour and 30 grams rye), stirred until there's no dry flour left. I like to add the water first and stir it in, because the flour mixes in more easily that way. Then it goes in the fridge with the lid on loose. A sealed jar of starter can build up gas, and I'll repeat what I tell everyone in my book: do not seal the jars, because they can (and will) explode. A fridge doesn't get a pass.

A few small things make the whole routine easier:

• Use a clear glass jar so you can see what's going on in there.
• Put a rubber band around the jar at the level of the starter, so you can tell later whether it moved.
• Clean the jar and your spatula right away after you use them. Flour and water hardens into something close to concrete within a few minutes, and if you have a lot to get rid of, put it in the trash instead of the drain.

How often to pull it out

Here's my rhythm. About once a week, I pull the jar out, feed it, bake with it, and put it back in the fridge until the next bake. If I'm not baking that week, I still try to pull it out and feed it every week, or every two weeks at the outside.

Two weeks is the line I hold. If a starter sits unfed in the fridge for longer than that, the top starts to harden. And I've noticed that mold begins to form after about a month. That's what I've seen in my own jars, so your kitchen and your fridge may behave a little differently. I keep to the two-week rule because it's easy to remember and it has worked for me.

Waking it up before you bake

If you're going to bake on Saturday, pull the starter out on Friday. The day before you bake, you take it out of the fridge, discard, and feed it.

Here's the order I follow:

1. Take the jar out of the fridge and discard most of it, keeping 30 grams.
2. Weigh a clean jar, add your 30 grams of starter, then the water and flour.
3. Stir until it's fully mixed, set the rubber band at the new level, and put the lid on loose.
4. Let it sit out and do its thing.

You'll know it's ready when it's bubbly, has doubled in size, and passes the float test: a small spoonful dropped into a glass of water should float. With a starter that's been fed and kept warm, that tends to happen about 4 to 6 hours after feeding, depending on the temperature and how thick your mix is. My kitchen is usually around 76 degrees in the daytime, which makes the timing friendlier. If yours runs colder, a spot in the oven with the oven turned off helps, and so does turning the oven light on for a little added warmth. Take the jar out of the oven before you turn the oven on. I've heard a lot of horror stories about that one, and you do not want to add to the pile.

One more note on timing. I've found it matters less what time of day you feed than whether the starter has hit its peak and started to fall before you feed it again. If you catch it after the peak, you're in good shape.

There's a trend going around where people bake with starter straight out of the fridge. I haven't tried it yet, so I can't tell you how it goes, but feel free to experiment.

What it looks like after some time in the cold

Fridge starters get a few looks that alarm people the first time. Here's what they mean.

A layer of liquid on top. That's hooch, and it means your starter is hungry. Stir it back in if you like a tangier flavor, or pour it off if you want things a little milder. Then feed it as usual.

A skin or crust on top. This forms when the starter is exposed to air and loses moisture. If it hasn't dried out too much, stir it back in. If it's hard, scoop it off and put it in the trash before you feed.

A smell like nail polish remover. Your starter is starving and has made more acid than it needs. It's not ruined. Feed it more often, even twice a day for a while, and the smell fades as it recovers.

Pink streaks or fuzzy mold. This is the one time you start over. Mold can't be saved and it isn't safe to use, so toss it, wash and sanitize the jar, and begin a fresh batch. I wrote a whole guide on telling the real emergency apart from a hungry starter, and it's worth a look if you're staring at a jar and can't decide.

If it's been in there too long

Everyone's experience is different. I've kept a starter on the counter for close to a week without feeding it, and it was fine after a feeding or two. If yours has been in the fridge for a few weeks and there's no mold, here's the revival:

1. Discard most of the starter, keeping about 30 grams.
2. Feed it equal parts flour and water by weight.
3. Repeat every 12 hours for several days, until it doubles in size and smells tangy.

That's the same move whether it's been a couple of weeks or a good deal longer, and it works more often than people expect. If it's slow to come back, a few feedings with rye or whole wheat flour give it a nudge, and a warmer spot helps. If you've been working through your discard at the same time, here's what I do with it.

For longer than a few weeks: dry it

If you're the kind of person who would be upset if your starter got moldy, got thrown out by someone you live with, or got baked in the oven by accident, you can make a backup. Spread a thin layer of starter on parchment paper and let it dry completely. Store it in an airtight bag, and freeze it if you like. To bring it back, crumble the dried starter into water and feed it until it's active.

I killed a couple of my own starters to travel and neglect before I got a system I could actually keep up with. A jar of dried starter in the freezer is the kind of insurance I wish I'd had back then.

Bake it anyway

A fridge starter is a forgiving one. You feed it, put it back, and pull it out when you're ready to bake. If you forget about it for a stretch, you now know how to wake it up, and if it doesn't make it, you can always start again.

The jar-by-jar details, including how I handle discard, how a starter should look at each stage, and what to do when it misbehaves, are in my book, Sourdough Starter (for Starters). If you'd like the symptom-and-fix list for your fridge door, that's the Is My Starter Okay? cheat sheet. Either way, bake it anyway.