Why Isn't My Sourdough Starter Rising?

A starter that won't rise is almost never a failure of character. It's one of five things: the starter is young, the kitchen is too cold, the culture is hungry, the water is fighting it, or the feed ratio is off. All five are fixed by adjusting one variable and keeping going, which is exactly the patience the process is designed to teach.

First, read what the jar is telling you

Before changing anything, look at what the starter did over the last 24 hours. The diagnosis comes from its behaviour:

• It bubbled a little and then stopped. Something is slowing it, usually temperature or a feed that ran out.
• It has never shown real activity. It's young, or the water or flour is working against it.
• It rises slowly, hours later than it should. Too cold, or the feed ratio is too small for the jar's schedule.
• It smells sharp and acrid, not sour. It's hungry or the acid has built up past the yeast's comfort.

It's young, and that's the most common answer

A sourdough starter takes seven to fourteen days to establish, and the course is blunt about the failure mode: impatience is the most common early error. In the first few days you're not growing bread yeast, you're growing a culture of wild yeast and bacteria from scratch, and that population starts at nearly zero. Day one of a starter is mostly stillness. Days two and three show a few bubbles. Real, reliable rising typically arrives in the second week.

The readiness test isn't the calendar, it's the doubling: the starter is ready to leaven bread when it reliably doubles within 4–8 hours of feeding, looks bubbly and domed at its peak, and passes the float test, where a teaspoon dropped in water floats because of the gas trapped in the culture. Until it does that, no amount of hoping will make the loaf rise. Keep feeding it, and let the jar set the schedule.

It's cold

Wild yeast is a living organism with a temperature preference, and the course targets 24–26°C for establishing a starter. A UK kitchen in winter, or an airy room in early autumn, runs five to ten degrees below that, and the starter responds by slowing to a crawl. A starter that would double in six hours at 25°C might take twelve at 18°C, and if you're judging it by the calendar rather than the jar, it looks broken when it's merely chilly.

The fix is warmth, not more flour: the airing cupboard, a radiator shelf, the top of the fridge, or an oven with just the light on. Feed the starter with water at around 25°C, and once it's active, keep it somewhere it can hold that pace. A cold snap doesn't kill a starter; it just puts it to sleep.

It's hungry

A starter on a 1:1:1 feed (equal weights of starter, flour, and water) doubles and then begins to fall as the food runs out. Leave it too long and it shows its hunger in two ways: a grey liquid layer on top, called hooch, and a sharp, acrid smell. Both are the same message, which is that the yeast has eaten everything available and is now producing alcohol instead.

The fix is to discard most of the starter, keep 50g, and feed it fresh flour and water. The discard step looks wasteful and feels wrong, but it's load-bearing: it resets the acid level, and acid build-up is what overwhelms a young culture before it's established. A starter fed on schedule stops producing hooch and starts producing bread.

The water and the flour are fighting it

Two ingredients can sabotage a starter without you noticing. Chlorinated tap water can inhibit yeast activity, which matters most in the first week when the culture is at its most fragile. The course's advice is pragmatic: if your tap water tastes good, it's probably fine; if it's heavily treated, use filtered water or leave a jug out overnight so the chlorine dissipates.

Flour matters at the start and then stops mattering. The initial culture comes from the wild yeast living on the outside of wheat grains, so wholemeal or rye flour, which retains the bran and germ where those organisms concentrate, establishes a starter faster than white flour. Once the culture is going, strong white bread flour feeds it well, and plain flour, lower in protein, feeds it less effectively. Use strong white for the daily feed and the difference shows.

What not to do

Three instincts to resist. Don't start again: a sluggish week-old starter is ahead of a fresh one, and the restart resets the clock for nothing. Don't feed it more to force activity: a 1:1:1 ratio on a schedule does more than a triple feed once a week. And don't bake with it until it doubles on its own: the course names this as the most common reason early sourdough loaves come out dense, and the fix is to keep the starter, adjust one variable, and bake again when the jar is ready.

The whole process, from the day-one mix to the float test and the first loaf, is in the sourdough course, and the bread course covers the same patience applied to commercial-yeast bread for anyone who wants a loaf this weekend rather than this fortnight. When the starter does come alive, the boule shaping and scoring quests turn it into a loaf worth the wait.

The short version

• A starter that won't rise is one of five things: too young, too cold, hungry, chlorinated water, or the wrong flour.
• Seven to fourteen days is normal, and the readiness test is reliable doubling within 4–8 hours of feeding, not the calendar.
• A cold kitchen slows a starter to a crawl: feed with 25°C water and keep it somewhere around 24–26°C.
• Hooch and an acrid smell mean it's hungry: discard down to 50g and feed 1:1:1 by weight.
• Use wholemeal or rye to start, strong white to maintain, and unchlorinated water if your tap water is heavily treated.
• Don't restart, don't overfeed, and don't bake until it doubles: impatience is the most common cause of both a stalled starter and a dense first loaf.