If you can stir flour into water, you can make a sourdough starter. This is the recipe we use at the Hub.
A sourdough starter recipe needs only two ingredients — flour and water — fed once a day for seven days at room temperature. We use 50g wholemeal flour + 50g lukewarm water on Day 1, then switch to strong white from Day 3, discarding half and refeeding 1:1:1 each morning. By Day 7 it should double within six hours of a feed. Print the card below and you're set.
At a glance
Time7 days
Yield~150g starter
Hydration100%
DifficultyEasy
How long does a sourdough starter take?
A sourdough starter takes about 7 days at a UK room temperature of 20–22°C, fed once daily with flour and water. In a cooler kitchen — 16–18°C in spring or autumn — count on 10 days. Below 16°C, expect up to 14. The recipe doesn't change; only the calendar does. You'll know it's ready when it doubles in volume within six hours of a feed.
UK kitchen reality check. At 18°C, this recipe will take 10 days, not 7. The numbers below are honest about it.
| Kitchen temperature | Maturation timeline | UK months this is typical |
|---|---|---|
| 22°C | 7 days | June–August (warm kitchen) |
| 20°C | 8 days | May, September (typical heated kitchen) |
| 18°C | 10 days | March–April, October |
| 16°C | 12–14 days | November–February (UK winter average) |
Ingredients
What is the ratio for a sourdough starter recipe?
A sourdough starter recipe uses a 1:1:1 ratio by weight — equal grams of mature starter, flour, and water. From Day 3 onwards, that's 50g starter mixed with 50g strong white flour and 50g lukewarm water, fed once a day. Day 1 is the only exception: just 50g wholemeal flour and 50g water, with no starter to add yet.
Scale the recipe:
For Day 1 (the kick-start)
- 50g strong wholemeal flour (we use Marriage's Strong Wholemeal)
- 50g lukewarm tap water (about 25°C — body temperature on the wrist)
For Day 2 to Day 7 (the daily feed)
- 50g strong white bread flour (Shipton Mill, Doves Farm, or Allinson's)
- 50g lukewarm tap water
- 50g the previous day's starter (the rest goes in the bin or compost)
Every feed is the 1:1:1 ratio — equal weights of starter, flour, and water. The maths never changes; only the day on the calendar does.
UK flour brand notes
Can I use plain flour to start a sourdough starter?
You can, but you shouldn't if you want it ready in seven days. Plain flour (Allinson's, Marriage's, supermarket own-brand) has less protein and fewer wild yeasts than strong bread flour or wholemeal. A starter built on plain flour will take 10–14 days instead of 7, and it'll be weaker when it gets there. For Day 1, use wholemeal. From Day 3, switch to strong white.
- Best: Marriage's, Shipton Mill, Doves Farm Organic — UK-milled, higher protein.
- Good and easy to find: Allinson's Strong White (every UK supermarket).
- Avoid for the first week: plain flour, self-raising, "00" pasta flour — too low in protein and too clean of wild yeast.
Equipment
- A 1-litre glass jar (Kilner with the rubber seal removed, or an old jam jar)
- Digital kitchen scales (1g resolution — non-negotiable)
- A wooden spoon or silicone spatula
- A rubber band (to mark the starting level on the jar)
- A tea towel or breathable lid (NOT airtight — gas needs to escape)
- A clean glass to feed into (optional; some keep two jars for rotation)
- A spot in the kitchen that stays 18–22°C (top of the fridge, near the boiler cupboard, an airing cupboard)
- A small notebook or the phone Notes app (you'll be glad you tracked it)
Method
Day 1 — Mix (the wholemeal kickstart)
1. In your clean jar, stir 50g wholemeal flour into 50g lukewarm water until no dry flour remains. Cover loosely. Mark the level with a rubber band. Leave at room temperature for 24 hours.
What you should see: a thick, beige porridge. Probably no bubbles yet. Possibly a faint earthy smell. This is normal.
Wholemeal carries more wild yeast per gram than white because the bran fraction is where the microbes live — Vanessa Kimbell's Sourdough School calls this the wholemeal kickstart.
Day 2 — Stir and wait
2. Open the jar. You may see a few bubbles on top — or none. Stir vigorously for 10 seconds to oxygenate. Re-cover. Leave another 24 hours. Do not feed yet.
What you should see: tiny bubbles starting to form. Smell is still flat or slightly grassy. The level may have risen 1–2cm.
Day 3 — First discard and switch to white
3. Discard all but 50g of the mixture (eyeball — you don't need to weigh the discard). Add 50g strong white bread flour and 50g lukewarm water. Stir well. Re-cover. Leave 24 hours.
What you should see: pale beige paste with bubbles trapped throughout. The smell shifts — sharper, more vinegary, almost like nail-varnish. This is the early-stage acidity. Don't panic. It's a developmental stage, not a failure.
Day 4 — Twice-daily feeds begin (optional)
4. If your kitchen is 20°C or warmer, the starter may now be feeding fast enough to need two refeeds a day (morning and evening). If it's cooler, stay on once a day. The technique is identical: discard down to 50g, add 50g flour + 50g water.
What you should see: noticeably more rise — maybe 50% above the marked line at peak. Smell is mellowing slightly.
Day 5 — The false stall
5. Feed as on Day 3. Crucially: Day 4 to Day 5 often shows less activity than Day 3, not more. This is the famous "false stall" — the bacterial colony is regrouping. Every sourdough resource on the internet warns about this for a reason.
What you should see: possibly less bubble action. Possibly a thin grey liquid on top (the "hooch" — pour it off, stir it in, no problem either way). Smell: yoghurty, less vinegary.
Day 6 — Lift-off
6. Feed as on Day 3. By the afternoon, you should see a clear rise — the starter should reach roughly double the marked rubber band level within 6–8 hours of the feed.
What you should see: a domed, bubbly mass at peak. Smell: like ripe yoghurt, maybe with a hint of apple. The texture is loose and stretchy.
Day 7 — The float test
7. Feed in the morning. Six hours later, drop half a teaspoon of the risen starter into a glass of room-temperature water.
- Floats = ready to bake with.
- Sinks = give it another 24 hours and test again.
If it floats, you have a sourdough starter. Welcome.
What it should look like on Day 7
SightDoubled in volume within 6 hours of feeding. Domed top, full of bubbles of mixed sizes throughout.
SmellRipe yoghurt, mildly fruity, faintly sweet. Not sharp vinegar; not nail varnish.
TextureLoose, stretchy, holds tracks from a spoon for a second before sinking back.
Float testHalf a teaspoon floats in room-temperature water.
Scaling the recipe
Most home bakers don't need 150g of mature starter. A 25g + 25g + 25g feed works fine for a single loaf a week, uses less flour, and produces less discard. Use the slider above the Ingredients block to halve, double, or keep at standard — every gram value in the recipe updates live.
| Scale | Per feed | Day 7 yield | Right for |
|---|---|---|---|
| Half | 25g + 25g + 25g | ~75g | One loaf a week |
| Standard | 50g + 50g + 50g | ~150g | Two loaves a week, plus discard recipes |
| Double | 100g + 100g + 100g | ~300g | Multiple loaves + dehydrated backup |
Storage after Day 7
Do I have to keep feeding it every day forever?
No. Once your starter is mature, you have three options. Daily bakers keep it on the counter and feed every 12–24 hours. Weekly bakers keep it in the fridge and feed once a week. Occasional bakers dry it on baking paper, snap it into flakes, and store it in a jar for months. All three keep the same starter alive — you just choose the rhythm that fits your life.
Counter (daily baker)
Feed every 12–24 hours, 1:1:1 ratio. Use as needed; never let it sit hungry more than 24 hours at room temperature or it'll start to sour and lose lift.
Fridge (weekly baker)
Feed once, let it rise for 2 hours on the counter, then transfer to the fridge. Take it out and feed it the day before you want to bake. We cover this in How to Feed a Sourdough Starter.
Dried (the insurance policy)
Spread a thin layer on baking paper. Air-dry for 48 hours until it cracks. Snap into flakes. Store in a jar. Lasts a year. Rehydrate with equal water to wake.
Troubleshooting — the four most common problems
It hasn't bubbled by Day 4
Likely cause: kitchen is below 18°C. Move it somewhere warmer (top of the fridge, near the boiler, an airing cupboard). Add 12–24 hours to the timeline. Don't switch flour or change ratio — just give it time and warmth.
It smells like nail-varnish
This is acetone, produced when the bacteria are out-pacing the yeast. It's a normal Day 3–4 stage. Discard down to 50g and feed as usual. Within 48 hours the smell should turn yoghurty.
A grey liquid is sitting on top
That's hooch — alcohol the yeast produces when it runs out of food. Pour it off or stir it in (either works). It means you need to feed more often or use a slower ratio (try the 1/3/3 rule covered in Article 7).
It rose, then collapsed
The starter peaked and over-fermented before you got to it. Next time, feed sooner after it doubles, or move it somewhere cooler. A collapsed starter still works — it just isn't at peak when you want to bake.
Frequently asked questions
What is the ratio for a sourdough starter recipe?
A sourdough starter uses a 1:1:1 ratio by weight — equal grams of mature starter, flour, and water. From Day 3 of the recipe that's 50g + 50g + 50g, fed once a day. Day 1 and Day 2 are different (no starter to add yet) — they're a single mix of 50g flour and 50g water that sits and develops wild yeast.
Can I use plain flour instead of bread flour?
You can, but it'll take longer. Plain flour has lower protein (around 9–10%) and fewer surface wild yeasts than strong bread flour (12–13%) or wholemeal (13%+). A starter built on plain flour will mature in 10–14 days instead of 7 and will produce weaker rise when it's done. For Day 1 use wholemeal; from Day 3 switch to strong white. UK Allinson's, Shipton Mill or Marriage's all work.
Is UK tap water OK for sourdough starter?
In most UK postcodes, yes. Hard-water areas (London, the Cotswolds, parts of East Anglia) may want to run the tap for 10 seconds first to dissipate chlorine — or filter through a Brita jug. Very soft-water areas (parts of Scotland and Wales) are fine straight from the tap. Bottled spring water works too but isn't necessary. Never use water hotter than 35°C — you'll kill the yeast.
Why do I have to discard half of my starter?
Two reasons. First, food supply — without discard, your starter would grow exponentially and the yeast would outpace the flour you feed. Second, acidity management — discard removes built-up acid so the new feed isn't too sour for the bacteria to thrive. From Day 7 onward, the discard isn't waste — it goes into pancakes, crackers, and pizza dough.
Can I scale the recipe up or down?
Yes — use the slider above the Ingredients block. Standard is 50g per feed (you'll end Day 7 with about 150g mature starter). Half (25g) is plenty if you only bake one loaf a week. Double (100g) is right if you're baking two or more loaves a week or planning to dehydrate some as backup. The 1:1:1 ratio stays the same; only the total grams change.
How do I store the starter after Day 7?
Three options. Daily bakers keep it on the counter and feed every 12–24 hours. Weekly bakers keep it in the fridge after a final feed and refresh it once a week. Occasional bakers dry a layer on baking paper, snap it into flakes, and store in a jar — it'll keep for a year and rehydrate in 24 hours. Most home bakers find the fridge rhythm easiest.
What to bake next
Day 7 is a small thing and a big thing. You have a colony of wild yeast you grew yourself. From here, every loaf you bake will have flour, water, salt — and the culture sitting in that jar. Look after it; it'll look after you.
For the long version of this method with more troubleshooting, see How to Make a Sourdough Starter From Scratch. The full cluster sits at Complete UK Guide to Sourdough Starters.
And if seven days feels like a lot to commit to, our starter kits ship with a living culture so you can skip straight to Day 7.
