What is a sourdough starter, really?

A sourdough starter is a living culture of wild yeasts and friendly bacteria, kept going with regular feeds of flour and water. It is the engine behind a good loaf: it leavens the dough, deepens the flavour, and helps the bread keep for longer. You do not need any special equipment beyond a jar, a spoon, and a set of digital scales. In our Lancashire bakery and café, we treat our starter like a member of the team. It gets fed, kept warm, and used every day. At home, you can do the same, just on a smaller scale.

The important thing to remember is that a starter is not a one-off recipe. It is a routine. Once you understand what it looks and smells like when it is happy, you can adapt it to your kitchen, your schedule, and the flour you have in the cupboard.

Your first week: a simple feeding schedule

Begin with a clean jar that holds at least twice the volume of your starter. A 500ml jar is ideal. Use digital scales for accuracy, because volume measures like cups are too variable. Warm water is best: around 25°C, or just tepid to the touch. If your tap water is heavily chlorinated, leave it in a jug overnight or use filtered water.

• Day 1: Mix 50g wholemeal or rye flour with 50g warm water in the jar. Stir until no dry flour remains. Cover loosely with a lid or cloth.
• Day 2: You may see a few bubbles. If not, do not worry. Discard half the mixture, then feed with 50g flour and 50g water.
• Day 3 to Day 5: Repeat the discard-and-feed once a day. Keep the jar somewhere warm, around 21–24°C. A cupboard above a fridge or a spot near a radiator works well, as long as it is not too hot.
• Day 6 to Day 7: By now you should see regular bubbles and a rise after feeding. If the starter smells sharp and fruity, it is on track. Keep feeding once a day.

Wholemeal and rye flours give a starter a head start because they contain more nutrients. If you only have strong white flour, it will still work, but it may take a few extra days. Be patient. A starter is ready when it is predictable, not just when it bubbles.

Reading the signs: is it ready?

A lively starter has a few clear signals. After a feed, it should swell, dome slightly, and show plenty of bubbles on the surface and through the side of the jar. It should smell pleasant: yoghurt-like, slightly sour, with a hint of fruit. If it smells like nail varnish remover or acetone, it is hungry and needs feeding more often.

• Rise: It doubles in size within 4–6 hours of feeding at room temperature.
• Texture: It looks like a thick batter, with a web of bubbles when you stir it.
• Smell: Clean and tangy, not harsh or like alcohol.
• Float test: A small spoonful dropped in water should float, though this is not foolproof. Trust the rise and smell first.

If your starter has a layer of dark liquid on top, that is called hooch. It means the culture is hungry. You can pour it off or stir it back in for a more sour flavour, then feed as usual. If you ever see pink, orange, or fuzzy mould, throw the starter away and start again. Do not try to rescue it.

Feeding and keeping it alive

Once your starter is established, you can choose a rhythm that suits your baking. The key is to keep the ratio of starter, flour, and water balanced. A simple rule is 1:1:1 by weight: for example, 100g starter, 100g flour, 100g water. If you bake often, feed once or twice a day at room temperature. If you bake once a week, store it in the fridge and feed it once a week.

• Room temperature: Feed every 12–24 hours. Use it when it is at its peak, roughly 4–6 hours after feeding.
• Fridge: Feed once a week. Let it sit out for an hour after feeding, then return it to the fridge. Bring it back to room temperature and feed before baking.
• Discard: Do not pour it down the sink. Keep it in a tub in the fridge and use it for pancakes, crumpets, or flatbreads.

Keep your jar clean around the rim, and use a fresh jar every few feeds. This prevents dried crusts from causing mould. A well-kept starter can live for years, and many bakers name theirs. In Lancashire, we have been known to talk to ours on a quiet morning. It does not hurt.

Common problems and quick fixes

• No bubbles after a week: The kitchen is probably too cold, or the flour is old. Move it somewhere warmer and try a feed with rye or wholemeal flour.
• Watery and separated: It is hungry. Discard, then feed with a slightly thicker ratio, such as 1:2:1.5 starter to flour to water.
• Slow rise: Give it more time and a warmer spot. Do not add sugar or honey; it can upset the balance.
• Too sour: Feed more often, or use a larger ratio of fresh flour and water to starter, such as 1:5:5.
• Mould: Discard the whole starter. Sterilise the jar and begin again.

From starter to loaf: practical baking notes

When you are ready to bake, build a levain. Mix 100g active starter with 100g flour and 100g water, and leave it until it is bubbly and domed. Then use that levain in your dough. For a beginner's loaf, try 500g strong white flour, 350g water, 100g levain, and 10g salt. Mix, rest, fold, and prove slowly. Sourdough is not a race.

• Use a warm spot: A cool Lancashire kitchen will slow everything down. A linen-lined bowl in an airing cupboard or a turned-off oven with the light on can help.
• Watch the dough, not the clock: Bulk fermentation can take 4–8 hours, depending on temperature.
• Keep some back: Always save a spoonful of starter before mixing your dough, so you can feed it and bake again.
• Be consistent: Same flour, same water, same schedule. That is how you get a reliable rise.

Start with small batches and keep notes. Within a few weeks, you will know your starter's habits as well as you know your own. And if you pop into a Lancashire bakery or café and see a bubbling jar on the counter, you will know exactly what is going on. It is just flour, water, and a little patience, working together.