How to Know When Your Sourdough Starter Is Ready

The most common reason a sourdough loaf comes out dense is simple: the starter was not at its peak when it went into the dough. If you can read your levain accurately, you fix half of your bread problems before mixing. This article shows you the concrete signals that tell you a starter is ready, why timing matters more than any recipe clock, and how to adjust when your kitchen is warm or cold.

What “ready” actually means

A starter is a colony of wild yeast and lactic bacteria. After you feed it, the population climbs, peaks, then declines as food runs out. “Ready” means the colony is near that peak: maximum gas production, active yeast, and enough acidity for flavour but not so much that the gluten starts to weaken.

Bake before the peak and there is not enough yeast activity to lift the dough. Bake well after it, and the culture is hungry, acidic, and losing strength. Both give you a flat, gummy result.

The reliable visual signs

• Volume: A ready starter has roughly doubled or tripled from its fed level. Mark the jar with a rubber band at feeding time so you can see it clearly.
• Dome and bubbles: The surface is domed and covered in bubbles of varied sizes. When it flattens or sinks in the centre, it has passed peak.
• Smell: Ripe but pleasant, tangy and slightly yeasty. Sharp acetone or nail-polish notes mean it is over-hungry.
• Texture: Light and webbed, like a loose sponge, not a flat liquid.

The float test, and its limits

Drop a small spoonful into water. If it floats, it is full of gas and probably ready. This is a useful quick check, but it is not foolproof. A starter can float on trapped gas and still be past its prime, and a stiff starter may not float even when active. Use it as one signal among several, not as your only test.

Why timing beats the recipe clock

Recipes say “feed 8 hours before mixing” as a rough guide. But peak time depends on temperature, feeding ratio, and flour. A starter fed 1:1:1 at a warm 26C may peak in 4 to 5 hours. The same starter fed 1:5:5 in a 19C kitchen might take 10 to 12 hours. Trust what you see in the jar over any fixed number.

A real example

A home baker fed her starter at 8am at a 1:1:1 ratio during a summer heatwave, planning to mix at 4pm as her winter routine dictated. By noon the starter had peaked and collapsed. By 4pm it was flat and smelled of acetone. Her loaf barely rose. The fix was not a new recipe. It was feeding a leaner ratio later in the day, or mixing at noon when the starter was actually at its peak.

Common mistakes and how to fix them

• Baking on a cold, straight-from-the-fridge starter. Give it one or two feeds at room temperature first so the yeast wakes up.
• Ignoring temperature swings. Track your kitchen temperature. A five-degree change moves peak time by hours.
• Feeding too little flour. A hungry starter over-acidifies fast. Increase the feeding ratio in warm weather to extend the window.
• Relying only on the float test. Combine it with volume, smell, and dome.
• Using it right after feeding. A just-fed starter has not built enough gas yet. Wait for the rise.

Action checklist before you mix

• Mark the fed level on the jar and watch for a clear doubling or more.
• Confirm a domed, bubbly surface, not a flat or sunken one.
• Smell for a pleasant tang, not sharp solvent notes.
• Run a float test as a secondary confirmation.
• Note the room temperature and adjust your feeding time next round.

Conclusion

Reading your starter is a skill you build in a week of paying attention. Keep a short log of feeding time, ratio, temperature, and peak time. Within a few bakes you will predict the window without checking the jar every hour. Your next step: mark the jar tonight and watch when it peaks, then feed to hit that peak at your ideal mixing time.

FAQ

Can I use my starter after it has peaked and fallen?

You can, but expect a slower, more acidic rise. If it has only just fallen, it is usually still fine. If it collapsed hours ago and smells sharp, feed it again and wait.

How long is the peak window?

Usually one to two hours around the top of the rise, longer in a cool kitchen and shorter in a warm one. A leaner feeding ratio widens the window.

My starter never floats. Is it dead?

Not necessarily. Stiff or rye-heavy starters may not float even when active. Judge by rise, bubbles, and smell instead.

Should I feed once or twice before baking?

If the starter lives in the fridge, two room-temperature feeds usually restore full strength. A starter kept at room temperature often needs just one.

Does a bigger rise mean a better loaf?

Not on its own. A very high rise with a thin, watery texture can mean the culture is weakening. Look for a strong, webbed structure, not just height.