At fridge temperature the yeast and bacteria don't die — they slow down to a crawl. Activity that took eight hours on the counter takes days. A starter that would exhaust its food overnight at room temperature can coast for a week or more.
The two populations slow at different rates, though, and that's worth knowing. The acid-producing bacteria stay relatively more active in the cold than the yeast does. So a starter kept refrigerated for a long stretch drifts more sour and less powerful — it's not damaged, it's just imbalanced, and a couple of warm feeds rebalance it.
Feed it, let it start, then chill it. That's the whole method, and the middle step is the one people skip.
Take the jar out, discard down to 20 g, feed 1:2:2 (20 g starter, 40 g flour, 40 g water). Leave it on the counter for one to two hours — long enough for fermentation to get going and for the culture to be actively feeding — then put it back in the fridge.
Putting a freshly fed starter straight into the cold means it barely gets started before everything slows down, and it arrives at next week hungry and sluggish. Two hours of head start makes the difference between a starter that's fine after a week and one that needs rescuing.
A starter out of the fridge is cold, sluggish, and usually more acidic than it should be. One feed will often produce a rise that looks convincing but doesn't have the power to lift a loaf — this is the most common reason a bake fails after a fridge stint.
Give it two. Feed 1:2:2, wait until it peaks at room temperature, then feed again and use it at the second peak. For a starter that's been cold under a week, the first feed may take 8–12 hours and the second 4–6. That's most of a day, so start the night before.
You'll see the difference. The first rise is often slow and slightly flat-topped; the second is faster, domes properly, and smells clean rather than sharp. Use it at that second peak.
| Time in the fridge | What you'll find | To use it |
|---|---|---|
| Up to 1 week | Looks normal, maybe a little liquid | One feed, maybe two |
| 2–4 weeks | Grey hooch on top, sharp smell | Pour off, two feeds |
| 1–3 months | Dark liquid, strong solvent smell, no activity | Three or four daily feeds |
| Longer | Often still alive under the surface | See reviving, below |
| Pink, orange, or fuzzy | Contamination — not recoverable | Discard and start again |
The only entry on that list that means the starter is actually dead is the last one. Everything else is a starter that's hungry and needs a few days of regular feeding to come back.
Notes from the counter
There's a guilt economy around sourdough starters that I think does real damage. People talk about them like pets, which makes forgetting one feel like neglect, which makes the whole hobby feel like an obligation you're failing at.
It's a jar of flour with a lot of microbes in it. It is extremely hard to kill. Mine has been forgotten in the back of the fridge for months at a stretch and has come back every time.
If the guilt is the thing stopping you, the fridge rhythm is the answer: four minutes a week, and a bake whenever you feel like it. That's a much better relationship than a daily ritual you resent by March.