Making Sourdough Starter from Everyday Flour

Why a jar of flour and water is worth your time

Every bag of plain flour in your cupboard is already carrying wild yeasts and friendly bacteria. Add water, leave it somewhere reasonably warm, and those invisible passengers wake up and start to multiply. That is a sourdough starter: no sachets, no special equipment, no trip to a specialist shop. It costs pennies to make and keeps going for years if you look after it.

There is a quiet satisfaction in it. A kilo of own-brand plain flour is well under a pound, and a starter uses a tablespoon at a time. Nothing is flown in, nothing arrives in a plastic pouch from a factory, and the only food miles involved are the ones between your cupboard and the worktop. It is also a genuinely useful thing to have: a lively starter will raise bread, and it will make crumpets, pancakes and scones that taste far better than anything that comes out of a packet.

Choosing your flour and kit

You do not need to buy anything special. A starter will work with the cheapest plain flour on the shelf. That said, different flours behave differently:

• Wholemeal or rye: ferments fastest, because the bran and germ carry more of the microbes you want. Rye starters can be almost alarmingly energetic.
• Plain white: slower to get going, but gentler in flavour and easier to keep balanced.
• A 50/50 mix of wholemeal and plain white: the forgiving middle ground, and what I would suggest for a first attempt.

For water, ordinary UK tap water is fine. If your area is heavily chlorinated, draw a jug the night before and let it stand, or use cooled water that has been boiled. For equipment, a clean 500ml jam jar, a fork, and either a loose lid or a square of cloth held on with an elastic band will do the job. Do not screw the lid down tight: the mixture produces gas, and pressure will build.

The first week, day by day

Day 1: weigh 50g of flour into the jar and add 50g of lukewarm water, around 25°C. Stir with a fork until you have a thick, slightly lumpy batter. Scrape the sides down, cover loosely and leave it on the worktop.

Days 2–3: stir once or twice a day. You will probably see bubbles and a modest rise, and you will allow yourself to feel smug. Do not. This early burst usually comes from bacteria that will fade, and it is not a sign your starter is ready.

Days 3–5: start feeding once a day. Tip out all but about 25g, then add 50g flour and 50g water. This "discard and feed" step keeps the jar from overflowing and gives the yeasts fresh food rather than a pool of spent, acidic liquid.

Days 5–7: expect a lull. It may smell of nail varnish or faintly unpleasant for a day or two before settling into something yeasty and sour, like yogurt. Keep feeding daily and keep it warm: a shelf in the airing cupboard, the top of the fridge or a spot away from a cold window. Below about 18°C everything slows to a crawl; above 30°C you are encouraging the wrong microbes entirely. Most starters in a normal British kitchen are rising reliably within seven to ten days.

Reading the signs

A starter is ready to bake with when it does all of the following after a feed:

• Doubles in size within four to eight hours, then sinks back down.
• Looks domed and spongy, with bubbles running all the way through rather than just froth on top.
• Smells pleasantly sour, like yogurt or beer, rather than sharply of acetone.

If it only foams at the surface, it is getting there but not yet strong enough. Feed it and try again tomorrow. A starter that reliably doubles is far more valuable than one that merely looks busy.

Keeping it alive without it taking over your life

If you bake most weeks, keep it on the worktop and feed it daily with equal weights of starter, flour and water. If you bake occasionally, use the fridge:

• Feed it, leave it out for an hour, then seal the lid properly and refrigerate. It will keep for up to a fortnight.
• To revive, bring it out, let it come to room temperature and feed it as normal, twice if it has been dormant a while.
• A dark layer of liquid on top is called hooch. It means hunger, not spoilage. Stir it in or pour it off, then feed.
• Grey or pink fuzzy patches mean mould. Bin it and start again, and wash the jar thoroughly with hot soapy water.
• A dry crust around the rim is harmless. Wipe it away when you next feed.

Give it a name if it helps. It sounds silly, but it makes you far more likely to remember the daily feed.

What to make, and what to do with the discard

The obvious answer is bread, but the discard you pour off each day is not waste — it is batter waiting for a purpose. Keep a tub in the fridge and add to it rather than binning it, then use it within a week.

• Crumpets: roughly 200g starter, 100g plain flour, 200ml milk or water, a teaspoon of sugar, half a teaspoon of bicarbonate of soda and a good pinch of salt. Whisk, rest for half an hour, then cook in buttered rings over a low heat until the tops set and the bubbles pop.
• Pancakes: 100g discard, 100g plain flour, one egg, about 150ml milk, a pinch of salt. Whisk and cook straight away.
• Scones, Yorkshire puddings and waffles: all improve with a spoonful or two stirred into the mix.

The whole thing rewards a relaxed attitude more than precision. Weigh things if you like, but a starter fed by eye with roughly equal parts will still make good bread. Start a jar this weekend, keep it warm, feed it when you remember, and you will have a kitchen companion that costs almost nothing and quietly gets better with age.