· Nora Whitfield
How to make a sourdough starter, day by day
Making a starter is genuinely simple, and almost everybody who gives up does so for the same reason: they cannot tell whether what they are seeing is progress or failure. Day three looks like triumph and is usually a false alarm. Day five looks like death and is usually fine. Knowing the shape of the two weeks in advance is most of the battle.
What follows is that shape. You need flour, water, a jar and about five minutes a day.
What you actually need
Flour. Start with wholemeal — rye or whole wheat. The bran carries far more wild yeast and bacteria than white flour, so a wholemeal start gets going faster. You can transition to white later if you prefer; most people keep a little wholemeal in the mix permanently.
Water. Tap water is fine in most places. If yours is heavily chlorinated, leave it out uncovered for an hour first. Lukewarm rather than cold helps in a cool kitchen.
A jar with room. Three times the volume of what you keep in it, because a lively starter triples. A clear one with a scale on the side saves you the guesswork this entire article is about — our 900 ml graduated jar is built for exactly this, and the container page works through the sizing arithmetic if you want the numbers.
A cover that breathes. Fermentation makes carbon dioxide continuously. A lid resting on top or a cloth held with a band keeps dust out and lets gas leave. A sealed jar builds pressure.
Days 1 to 2 — mix and wait
Combine 50 g of wholemeal flour with 50 g of water in the jar. Stir until no dry flour remains — it will be a thick paste rather than a batter. Level the surface, mark where it sits, cover loosely and leave it somewhere warm.
Then do nothing for 48 hours. Not "check it every four hours" — genuinely nothing. The microbial community is sorting itself out, and at this stage the bacteria that dominate are not the ones you want long term. Interfering does not speed it up.
What you will see: very little. Perhaps a few bubbles at the surface by hour 36. Perhaps nothing at all. Both are normal.
Day 3 — the false dawn
This is the day that fools everyone. Many starters erupt on day 3: they double, they smell sharp and cheesy, they look exactly like success.
They are usually not. That early burst is typically driven by Leuconostoc and similar bacteria, not by the yeast and lactic acid bacteria that will eventually run your starter. It is a phase, and it passes.
Feed it anyway. Discard all but about 50 g, then add 50 g flour and 50 g water. Mark the new level. Cover.
Days 4 to 6 — the quiet stretch
And then, very often, everything stops. The starter that doubled on day 3 sits flat for two or three days, smells faintly of nail varnish or wet cardboard, and looks utterly dead.
This is the single most common point of abandonment, and it is not failure. The early bacteria have exhausted their niche and died back; the organisms that will actually run the culture are still establishing. The pH is dropping, which is precisely what makes the environment hospitable to them and hostile to everything else.
Keep feeding once a day. Same routine: discard down to about 50 g, add 50 g flour and 50 g water, mark the level.
If your kitchen is cool this stretch lasts longer. At 66 °F everything crawls; at 78 °F it moves along briskly. This is where a temperature reading stops the waiting from feeling like a mystery — a slow starter and a sick starter look identical, and only the number tells them apart. A stick-on strip on the side of the jar is the simplest way to have it, and clear glass is what lets you read the texture at the same time.
Days 7 to 10 — the real thing starts
Somewhere in here, genuine activity appears. It looks different from the day 3 burst: slower, steadier, more regular. The surface domes rather than froths. The smell shifts from sharp to something closer to yoghurt or beer.
Now the rise starts to be worth measuring. Feed, mark the level, and note two things: how far it rises, and how long it takes. Those two numbers are the whole of what you need to know about your own starter, and they are personal to it — no video will give them to you.
By now you may want to move to twice-daily feeding if it is peaking and falling within twelve hours. If you are keeping a written note of all this, stop — a band and a chalk label on the jar do the same job without a notebook, and they are still there tomorrow whether or not you remembered.
Days 11 to 14 — ready, and how you know
A starter is ready to bake with when it does the same thing twice in a row: reliably doubles, in a predictable number of hours, at a known temperature. That is it. Not a smell, not an appearance — repeatability.
The classic float test — a spoonful dropped in water floats — is a rough guide and worth knowing, but it is less reliable than the record you have been keeping. If it doubled in six hours yesterday and six hours today, it is ready, floating or not.
The two weeks at a glance
| Day | What to do | What is normal |
|---|---|---|
| 1–2 | Mix 50 g flour + 50 g water. Leave alone. | Little or nothing visible |
| 3 | Feed once | Often a dramatic rise — usually a false dawn |
| 4–6 | Feed once daily | Flat, sometimes odd-smelling. Not failure. |
| 7–10 | Feed daily, start recording | Steady, regular activity begins |
| 11–14 | Feed once or twice daily | Predictable doubling — ready |
Three things worth knowing
starters sequenced across four continents in the largest survey of sourdough microbiomes to date. It found little evidence that a starter's community depends on where it lives — and enormous variation between healthy ones
— Landis et al., eLife, 2021
That last point is the useful one for a beginner. Because healthy starters differ so much, comparing yours to somebody's video tells you almost nothing. Your own record — how far, how fast, at what temperature — is the only benchmark worth having.
Common problems
A dark liquid on top. Hooch. It means the culture has run out of food. Pour it off, feed more often or keep it cooler. Harmless.
It rises and falls before you get back. It peaked while you were out. Slide a band to the level at feeding time — if you return and the surface sits below the mark, that is exactly what happened. Feed a stiffer mix or move it somewhere cooler to stretch the timing.
It smells of acetone. Underfed. Feed twice daily for a few days.
Pink, orange or fuzzy growth. The one genuine failure. Discard and start again — this is the only situation where starting over is the right call.
Once it is alive
Keeping a starter is easier than making one. Feed it, scrape the walls, note the date. Our guide to feeding a starter covers ratios and timing, storing a starter deals with the fridge-versus-counter question, and cleaning the jar handles the housekeeping. If you are still choosing a jar, what size you need works through the volumes with the arithmetic, and what makes a jar worth owning covers the criteria.