How to make a sourdough starter

The false start

Most new starters bubble energetically on day two or three and then go completely flat and smell unpleasant — often of cheese or feet. This is not failure and it is not the starter dying.

What happens is that a group of bacteria unrelated to sourdough gets going first, produces a lot of gas, and then acidifies the mixture enough to kill itself off. The lull that follows is the gap before the lactic acid bacteria and wild yeasts that actually make sourdough establish themselves.

The correct response is to keep feeding on schedule and wait. Activity usually returns within a few days, and this time it is the right organisms.

Establishing one

Two weeks, a few minutes a day. FoodHQ does not publish salt percentages, pH figures or keeping times for home fermenting. Those are safety numbers, they are set by a food safety authority rather than by a cookery writer, and the right ones depend on what you are fermenting and where you are. In the UK the Food Standards Agency is the authority — use a recipe from it or from another body with the same standing, and treat this page as the explanation of why that recipe is shaped the way it is.

1. Mix roughly equal weights of flour and water in a clean jar to a thick paste. Wholemeal or rye flour to start with — they carry more wild organisms and more nutrients than white flour.
2. Cover loosely and leave somewhere warm — a warm kitchen rather than an airing cupboard.
3. Once a day, discard most of it and feed the remainder with fresh flour and water in the same proportion. Discarding is not waste; it keeps the acidity and the food supply in balance.
4. Expect vigorous bubbling around day two or three, then a flat, smelly lull. Keep going.
5. From about day five, switch to feeding twice a day if the kitchen is warm.
6. From day seven or so it should start rising and falling predictably after each feed.
7. It is ready when it reliably doubles within four to eight hours of feeding and smells pleasantly sour, yeasty and slightly fruity.

Keeping one going

• On the counter, fed once or twice a day, if you bake often.
• In the fridge, fed once a week, if you do not. Take it out and give it two or three feeds before baking.
• Hooch — a layer of dark liquid on top — means it is hungry. Pour it off or stir it in and feed.
• Discard is useful. Crumpets, pancakes, crackers, flatbreads and waffles all take it, and none of them need it to be active.
• Dry some as insurance. Spread a thin layer on baking paper, let it dry completely, crumble it and keep it in a jar. It can be revived.
• Rye or wholemeal feeds make a starter more active than white flour feeds.
• Fuzzy coloured mould means starting again. A clean starter should smell sour, never rotten.

What to expect

Timeline

Roughly one to two weeks to establish. Colder kitchens take longer.

Flour

Wholemeal or rye to start. You can switch to white once it is established.

Water

Heavily chlorinated tap water can slow it. Leaving water to stand overnight or using filtered water helps.

The float test

A spoonful of active starter dropped in water should float. A useful readiness check, though not infallible.

Naming it

Optional, and apparently universal.

Common questions