Simple Sourdough Starter Recipe: Your Key to Perfect Bread

There is nothing quite like the smell of freshly baked sourdough bread, but every good loaf starts with a healthy, active starter. This guide focuses on the practical side of building and maintaining a sourdough starter at home, including how temperature, timing, and feeding affect activity.

Want the exact numbers? My sourdough calculator works out starter feedings by ratio and dough hydration with baker’s percentages, in grams.

Sourdough starters are especially sensitive in cooler kitchens, and many problems come down to environment rather than technique. This recipe walks you through creating a reliable starter, how to recognise when it is ready to use, and how to store it for everyday baking.

Once your starter is active, you can put it straight to work in my sourdough bread recipe.

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How a Sourdough Starter Works

A sourdough starter is a living mixture of wild yeast and lactic acid bacteria that feed on the flour you add. The yeast produces carbon dioxide, which makes bread rise, while the bacteria create acidity that develops flavour and keeps the starter stable.

You may sometimes see a dark liquid on top of your starter. This is called hooch and simply means the starter is hungry. It is harmless and can be poured off or stirred back in before feeding.

That is all the science you need to get started.

Equipment You’ll Need

Starting a starter needs almost nothing, but these matter

A Closer Look at the Ingredients

A sourdough starter really only needs two things (plus time):

• Flour to start it 50 g of wholemeal rye on day one, organic if you can get it. The wild yeast and the lactic bacteria live on the outside of the grain, so a wholegrain flour arrives with its own population already on board and a white flour does not. Rye brings something else with it: it tends to start sprouting before it is harvested, so its starch-digesting enzymes are already active and there is sugar ready for the microbes from the first hour. Instead: malted country grain or wholemeal wheat both work, they are just a little slower off the mark. Plain white flour will get there eventually, it simply takes longer and looks dead for longer while it does.
• Flour to keep it on 50 g at every feed after the first, bread flour or wholemeal. Once the population is established it no longer needs the bran to recruit from, and a white flour gives you a starter that behaves predictably and is easy to judge by eye. Instead: plain flour is fine. Keeping it on wholemeal is not wrong, it just rises faster and needs feeding more often.
• Water 50 g at room temperature, matched to the flour by weight rather than by volume. Warm water is not a shortcut: it speeds the bacteria up more than the yeast, which gives you a sour, sluggish starter. Instead: if your tap water smells strongly of chlorine, filter it or leave a jug standing overnight. Chlorine at tap levels slows a starter rather than killing it, so this is worth doing and is not worth buying bottled water for.

How to Make a Sourdough Starter, Step by Step

Seven stages across roughly a week. The routine is the easy part; the difficult part is knowing what the jar is telling you, which is what the sections underneath are for.

1. Day 1: mix the first 50 g of flour with 50 g of water. Use wholemeal rye for this first mix, not white. Stir it to a thick paste with no dry pockets, then cover the jar loosely. A normal wash is enough for the jar. Leave it somewhere around 20 to 26 C. If your kitchen is colder in winter, the top of the fridge or a shelf near a boiler is usually the warmest steady spot.The bran carries far more of the wild yeast and bacteria you are trying to catch, and rye gives them the readiest food. The jar wants to be clean, not sterile.Loosely matters: A sealed lid on a jar that is about to start making carbon dioxide is a jar under pressure.
2. Day 2: feed it, and do not read anything into what you see. Add another 50 g of plain flour and 50 g of water, stir it well and cover again.Some starters throw a lot of bubbles on day two and some do nothing at all, and neither tells you much this early. Stir properly, not one quick fold: working air through gives the yeasts the oxygen they need to build new cells, and they are the ones you are trying to grow.
3. Day 3: feed morning and evening, and start discarding. In the morning, another 50 g of flour and 50 g of water. In the evening, take out 100 g of starter and throw it away before you feed the same amounts again. Keep the discard in a tub in the fridge if you want to bake with it.The discard is not waste, it is the point. Every feed dilutes the acid and the growth inhibitors the microbes have been making, as well as adding food. Without taking some out first, the jar just grows and grows while the dilution gets weaker.
4. Day 4: discard and feed twice a day. Same routine morning and evening: 100 g out, then 50 g of flour and 50 g of water in. Mark the jar with an elastic band at the level of the starter after each feed.By now you should see a rise and fall between feeds, not random bubbling, and the smell should be moving from sharply sour or slightly cheesy towards beer or yoghurt. The band shows you how far it actually rises, so you are not guessing.
5. Day 5 onwards: test it by watching it double. A finished starter roughly doubles within four to eight hours of a feed, then sinks back. If yours is not doing that, carry on with the day 4 routine and give it time. Do not judge it on smell alone at this stage.Five to seven days is normal, and ten to fourteen is common in a cold British kitchen. The sourness is the bacteria, which arrive first and are never in short supply. What you are waiting for is the yeast to catch up, and the rise is the only honest measure of that.
6. Storing it: into the fridge once it is reliably doubling. Loose cover, and feed it once a week, or whenever you take some out, replacing what you removed with equal weights of flour and water. Give it headroom in the jar.Cold slows everything down so much that a weekly feed is enough, and a fridge starter neglected for a month is usually still recoverable, not dead. A starter fed and left somewhere warm can triple, and a full jar climbs out over the worktop.
7. Waking it up before you bake. Take 100 g of starter into a clean jar and mix it with 50 g of warm water and 50 g of plain flour, then leave it at room temperature for at least three hours, or overnight if you can. Use it while it is rising and at its bubbliest, not after it has peaked and sunk back.That is when it has the most lifting power. One wake-up feed is enough for a starter fed weekly. One that has sat in the fridge for a month or two may want two or three feeds over a couple of days before it is back to full strength.

Recipe Card for Sourdough Starter

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Why It Bubbles on Day Two and Then Goes Quiet

This is the single most common thing to happen to a new starter, and almost nobody explains it. You mix flour and water, nothing happens for a day, then on day two or three the jar is full of bubbles and climbing. You feel like you have cracked it. Then it stops dead, and stays flat for days while you wonder what you did wrong.

Nothing. What is happening is that a starter holds two very different sets of microbes, and they do not arrive at the same speed. The bacteria grow far faster than the yeasts and end up outnumbering them by a factor of a hundred or more. That early burst of gas is largely them, and some of the species responsible in the first day or two die back once the jar turns acid. What follows is the quiet stretch: the bacteria have acidified their own environment, and the yeasts, which are the ones that will eventually raise your bread, are still building numbers from a standing start.

That is also why the routine is built the way it is. Every feed does two jobs, and the less obvious one matters more: it adds food, and it dilutes the acid and the other growth-inhibiting substances the microbes have produced. Discarding before you feed is what keeps that dilution meaningful. Feed more often, or feed more heavily, and the yeasts get a better run at it and the starter ends up with more lifting power.

It explains the temperature advice too. Bacteria are happiest somewhere well above a normal kitchen; the yeasts, in an acid jar, do better at around 20 to 25 C. So warm is helpful and hot is not. If a starter is stalling in a cold room, moving it somewhere gently warmer is the right call, but standing it on a radiator or in an oven with the light on tilts the balance towards bacteria and gives you something very sour that still will not rise. If your kitchen is the problem rather than the starter, my guide to dough that will not rise in a cold kitchen goes through the warm spots worth trying.

Mould, Kahm Yeast and When to Start Again

This is the thing people worry about most, and the honest answer is that mould on a starter is uncommon and easy to recognise once you know what you are looking at. The rule is simple and it does not bend: if it is mould, throw the whole jar away and start again. Do not scrape it off and use what is underneath, because what you can see on the surface is not the whole of what is there.

• Mould is fuzzy and three-dimensional, standing up off the surface like a tiny carpet. It is usually green, black, blue or grey, and it appears in distinct spots that spread outwards rather than as an even layer. Bin it.
• Pink or orange colouring counts as a discard signal in its own right, even without any fuzz. It is uncommon, and it is not something to reason your way past.
• Kahm yeast is a thin, flat white or cream film across the surface, sometimes slightly wrinkled, with no fuzz and no colour. It is harmless. Scrape it off, discard a good portion of the starter underneath, feed as normal, and it usually clears within a couple of feeds. It tends to turn up on starters that have been left too long between feeds.
• Hooch, a layer of grey or brownish liquid on top, is not mould at all and is not a problem. It means the starter is hungry. Pour it off or stir it in, then feed.
• Grey or dull discolouration of the starter itself, with no fuzz and no pink, is normally just oxidation at the surface. Stir it through and feed.

Nothing here involves tasting a starter to work out whether it is safe. If you are looking at fuzz or at pink, the jar goes in the bin. A week of feeding is a cheap thing to lose.

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FAQ for Sourdough Starter

How long does it take to make a sourdough starter from scratch?

Usually 5-7 days of daily feeding, though it can take up to 10-14 days in a cold kitchen before it is active and doubling reliably.

How do I know when my starter is ready to bake with?

It should double within 4-8 hours of feeding, look bubbly and domed, and smell pleasantly sour. The float test - a spoonful floating in water - is a handy check.

How often do I feed it?

Once a day at room temperature while establishing it, then once a week once it lives in the fridge. Bring it back to room temperature and feed it the day before baking.

What is sourdough discard and can I use it?

Discard is the portion you remove before feeding. Do not bin it - use it in my sourdough focaccia or other bakes.

My starter is not rising - what went wrong?

Most often the kitchen is too cold or it just needs more time. Keep it warm (around 24-26C), feed consistently, and be patient - my dough-not-rising guide digs into this.

My starter passes every other test but sinks in the float test. Is it ready?

Probably, yes. The float test is a handy check and it is not a reliable one: a starter that is doubling on schedule, domed and bubbly, and smelling of beer or yoghurt can still sink, particularly if it is on the thick side or you took the spoonful after it had peaked and begun to fall. Trust the rise instead. If it reliably doubles within four to eight hours of a feed, it will raise bread whatever it does in a glass of water. Take the sample while it is climbing rather than after, and you will usually find it floats anyway.

My starter is too thick, or too runny. Should I change the amounts?

Yes, and it is not cheating. Flours drink very different amounts of water: rye and a strong wholemeal take far more than a supermarket plain flour, so the same 50 g and 50 g gives a stiff paste in one kitchen and a batter in another. Aim for the consistency of thick porridge, and adjust by 5 or 10 g at a time until you get there. What matters is that you keep it consistent from feed to feed, because that is what lets you read the rise.

My starter is sluggish and smells strongly of alcohol. What now?

It is hungry, and the usual fix is a bigger feed rather than a warmer shelf. Instead of equal weights, take 25 g of starter and feed it 75 g of flour and 75 g of water. That dilutes the accumulated acid and alcohol much further than a normal feed does and gives the yeasts a cleaner run. Do that once or twice a day for two or three days and most tired starters come back. If it is also cold, move it somewhere gently warmer at the same time, but do not put it anywhere hot.

What size jar do I need, and why does it keep climbing out?

Use something around a litre, and never fill it more than about a third. An active starter can double or triple after a feed, and a jar that looks generously empty in the evening can be over the sides by morning. A tall jar is better than a wide one because it makes the rise easy to see against an elastic band. Keep the lid resting on top rather than screwed down, so the gas has somewhere to go.

A Few Words from the Chef

Building a sourdough starter is less about precision and more about attention. Small variations are normal, and progress often comes in stages rather than on a fixed schedule.

Once your starter is active and reliable, you can use it straight away or store it for future baking. It works naturally with my sourdough bread recipe, and it is also excellent for softer, high-hydration bakes like sourdough focaccia.