Blog / 7 October 2026

Why did my sourdough starter stop rising on day 4?

Your starter is not dead. A new starter that rose beautifully on day 2 or 3 and then went completely flat around day 4 is doing what nearly every new starter does. The first rise came from bacteria that cannot survive in a sour jar, and the yeast that will eventually raise your bread has not taken over yet. Keep feeding it.

That is the whole answer. The rest of this post is the explanation, because this is exactly the kind of thing I had nobody to ask about in January, and it is a very lonely thing to google while staring at a jar.

The rise that got your hopes up

Flour carries all kinds of microbes. In the first few days the fast ones win. Bacteria such as Leuconostoc produce a lot of gas very quickly, so the jar doubles, bubbles like it means it, and usually smells like something you would not want to describe at dinner.

It looks like a finished starter. It is not. It is a false start.

So the impressive rise was never a success, and the awful smell was never a failure. Both were the same guest, and that guest is about to leave.

Why it goes quiet

Those early bacteria make acid, and they cannot live in the acid they make. As the jar turns sour, they die off, and the rise goes with them. They are, quite literally, the authors of their own downfall.

What happens next is a handover. The acid-tolerant yeasts and lactic acid bacteria that make up a real sourdough starter are already in there, but there are not many of them yet and they are slow to get going. Until there are enough, the jar just sits there. Flat. Possibly smelling sharp, like vinegar or even nail polish remover.

That is normal. It does not feel normal. It is.

What to do (very little)

• Keep feeding once a day. Discard all but 25 g, then add 25 g flour and 25 g lukewarm water.
• Do not start over. A fresh jar puts you right back at day 1, with the exact same quiet days waiting for you.
• Keep it warm, around 24 to 26°C if you can. A cool kitchen can double the wait.
• Do not feed it more often to wake it up. I know. It feels like the caring thing to do. Every extra feed dilutes the yeast you are waiting for.
• Add some wholegrain or rye flour to the feed. It brings more microbes along, and more for them to eat.

Feed it and walk away. That is genuinely the instruction.

How long the quiet lasts

Usually two to four days. In a cool kitchen it can be a week or more, which feels like a month when you check the jar every hour.

The first sign that it is ending is the smell. It turns from sharp to something closer to beer or yoghurt. Small bubbles come back, and then the jar starts rising again after each feed. More slowly than the false start, far less dramatically, but on time, day after day.

A starter is ready to bake with when it doubles after a feed and does that several days in a row. For most people that is somewhere between day 7 and day 14. Predictable beats impressive.

When it really has gone wrong

Pink or orange streaks, or fuzzy mould on the surface, mean the jar goes in the bin. No discussion.

A grey or brown liquid on top does not. That is hooch, and all it means is that the starter is hungry. Stir it in or pour it off, and feed.

The day most people give up

Day 4 is where most new starters end up in the bin, and it is the one day they should not. That is why Sourdough Diary has a Starter School that walks you through these days one at a time. It goes by what the jar is doing, not by the calendar, so a slow jar is not marked as behind. Day 4 in it is called The quiet.