How to Make a Sourdough Starter From Scratch in 7 Days
How to Make a Sourdough Starter From Scratch
To make a sourdough starter, mix equal weights of flour and water in a jar, then discard most of it and feed it fresh flour and water every day for about seven days. Wild yeast and lactic acid bacteria living in the flour slowly build a stable culture. When the mixture reliably doubles in volume within four to eight hours of a feeding and smells pleasantly tangy, it's ready to raise bread.
That's the whole method. No commercial yeast, no grapes, no potato water, no secret ingredient — just flour, water, time, and a warm spot on the counter. This guide walks you through every day of the process, explains what you should see (including the discouraging quiet stretch almost everyone hits around day three), and tells you exactly how to know when your starter is strong enough for a real loaf.
We bake in Pacific Northwest kitchens, which tend to run cool and damp for much of the year. Cool counters don't stop a starter — they just slow it down — so throughout this guide you'll find timing notes for kitchens below 70°F (21°C) alongside the standard schedule.
What You Need Before Day 1
The equipment list is short, and you probably own all of it:
- A jar or container, roughly 3–4 cups (700–950 ml). Glass is nice because you can watch activity through the sides, but any food-safe container works. Don't screw a lid down tight; rest it loosely or use a cloth secured with a rubber band. Fermentation produces gas that needs to escape.
- A kitchen scale that measures in grams. This is the one tool worth insisting on. Cup measurements of flour vary too much for the consistent ratios a starter needs.
- Whole wheat or whole rye flour for the first few days. Whole grain flours carry more wild yeast and bacteria on the bran, so they get a culture going faster and more reliably.
- Unbleached all-purpose or bread flour for the later days and for ongoing maintenance.
- Water. Room temperature tap water is fine in most municipalities. If your tap water is heavily chlorinated and smells like a swimming pool, let it sit out uncovered for a few hours first, or use filtered water.
A flexible spatula or spoon for stirring and a rubber band to mark the starter's height on the jar round out the kit.
The 7-Day Schedule at a Glance
| Day | What you do | What to expect |
|---|---|---|
| 1 | Mix 60 g whole wheat flour + 60 g water | A thick paste; no activity yet |
| 2 | Rest, or stir once | Possibly a few bubbles |
| 3 | Discard down to 60 g; feed 60 g flour + 60 g water | Often a dramatic (false) rise, then collapse |
| 4 | Discard and feed, same amounts | Frequently quiet — this is normal |
| 5 | Discard and feed, switching toward white flour | Real bubbles return; sour aroma develops |
| 6 | Discard and feed, twice if very active | Noticeable rising within hours of feeding |
| 7+ | Discard and feed | Doubles in 4–8 hours; ready to test |
"Discard" means removing all but a small amount of the existing starter before adding fresh flour and water. It feels wasteful, but it's essential: without discarding, the population of microbes quickly outstrips its food supply, and the jar would overflow within days anyway.
Day-by-Day Instructions
Day 1: Mix
In your clean jar, stir together 60 g whole wheat (or rye) flour and 60 g room-temperature water until no dry flour remains. It should look like thick pancake batter. Scrape down the sides, stretch a rubber band around the jar at the level of the mixture, cover loosely, and set it somewhere between 70–75°F (21–24°C) if you can manage it. On top of the refrigerator, near (not on) a radiator, or inside the oven with only the light on are all classic warm spots.
Cool-kitchen note: below about 68°F (20°C), everything in this guide still works — expect each stage to take a day or two longer, and don't panic when day-three activity shows up on day four or five.
Day 2: Wait
Most starters show little or nothing on day 2. A few scattered bubbles are a good sign; a flat, inert paste is also completely normal. Give it a stir if you like — it incorporates oxygen and redistributes food — but no feeding is required yet.
Day 3: The False Rise
Here's where many first-timers get fooled. Around day 2 or 3, a lot of starters puff up impressively and smell frankly bad — think gym socks or overripe cheese. This is not yeast. It's a bloom of gas-producing bacteria that thrive in the young mixture's relatively neutral environment. They'll die off as the culture acidifies, and the starter will go quiet again.
Feed anyway: discard all but about 60 g of the mixture, then stir in 60 g whole wheat flour and 60 g water. Mark the new level with your rubber band.
Day 4: The Quiet Stretch
After the false rise collapses, days 4 and sometimes 5 are often nearly still. This is the point where the most starters get thrown out unnecessarily. Nothing is wrong. The acid-loving yeast and lactic acid bacteria you actually want are establishing themselves while the early bacterial bloom fades. Keep the routine: discard down to 60 g, feed 60 g flour and 60 g water, once a day.
Day 5: Real Activity
Somewhere around day 5 (later in a cool kitchen), genuine fermentation kicks in: small, even bubbles throughout the mixture, a visible rise after feeding, and a smell that shifts from funky to pleasantly sour — tangy yogurt, green apple, a hint of vinegar. From here you can start transitioning the feed toward your maintenance flour: try 30 g whole wheat + 30 g all-purpose + 60 g water with your usual 60 g of carried-over starter.
Day 6: Building Strength
If the starter is rising and falling predictably, move to all-purpose or bread flour feedings (60 g starter, 60 g flour, 60 g water). If it's very vigorous — doubling in just a few hours and collapsing before the next feeding — split the feedings to twice a day, roughly every 12 hours, so it never sits starving for long.
Day 7 and Beyond: The Readiness Test
A starter is ready to raise bread when it predictably doubles in volume within 4–8 hours of a feeding at room temperature, shows a domed top full of bubbles, and smells tangy rather than harsh. One good rise isn't enough; you want that behavior on two or three consecutive days, which proves the culture is stable rather than lucky.
Some bakers use the float test — drop a spoonful of starter into water, and if it floats, it's aerated and ready. It's a decent quick check but not definitive either way: an over-stirred ready starter can sink, and a starter mid-false-rise can float. Trust the doubling behavior and the smell over the float test.
Be honest with yourself here: seven days is the typical minimum, not a guarantee. Plenty of healthy starters need 10 to 14 days to hit reliable doubling, especially in cool kitchens or when starting with all white flour. Extra days of the same feeding routine cost you a few handfuls of flour and nothing else.
Once it passes the test, it's time to bake. Our beginner sourdough bread recipe is written specifically to be your starter's first loaf, with a full schedule from feeding the starter to slicing the bread.
How to Feed a Sourdough Starter (Ongoing Maintenance)
The standard maintenance feeding is a 1:1:1 ratio by weight — one part existing starter, one part flour, one part water. For most home bakers, 50–60 g of each is plenty; you only ever need enough ripe starter to seed your dough plus a spoonful to carry forward.
How often you feed depends entirely on where the starter lives:
- On the counter: feed once or twice daily. This suits people baking several times a week.
- In the refrigerator: feed once a week. Take the jar out, let it lose its chill for an hour or so, discard, feed 1:1:1, leave it at room temperature for 2–4 hours until it shows activity, then return it to the fridge. Cold storage is the practical choice for anyone baking once a week or less.
- Before baking from the fridge: give the starter one or two room-temperature feedings and wait for it to double before mixing dough. A cold, sluggish starter makes a slow, dense loaf.
Your discard, by the way, doesn't have to hit the compost. Unfed starter adds tang and tenderness to pancakes, waffles, crackers, and quick breads — a nice sidekick while you work through the fruit desserts in our pies and sweets collection.
Troubleshooting: What's Normal and What Isn't
A layer of gray or brownish liquid on top. That's "hooch" — alcohol produced when the starter runs out of food. It's harmless and simply means the starter is hungry. Pour it off (or stir it in for extra tang) and feed. If hooch appears daily, feed more often or move the jar somewhere cooler.
It smells like nail polish remover or vinegar. Also a hunger signal. The fix is the same: more frequent feedings, or a slightly larger feed relative to the carried-over starter (try 1:2:2 — for example, 30 g starter, 60 g flour, 60 g water).
It rose beautifully on day 3, then died. It didn't die — that was the false rise described above. Keep feeding on schedule and it will come back, usually within two to three days.
A dry, darkened crust on the surface. Common in loosely covered jars. Scrape it off, feed as usual, and cover a little more snugly (still not airtight).
Pink or orange streaks, or fuzzy mold in any color. These are the actual failure signs. Don't try to rescue it — throw the whole thing out, wash the jar thoroughly, and start over. A properly acidic starter resists contamination well, which is why this is rare after the first week.
Nothing at all by day 7. Check temperature first; a 64°F (18°C) counter can double every timeline in this guide. Move the jar somewhere warmer, make sure you're using some whole grain flour, and give it another week before judging.
Why Bother? What a Starter Earns You
A jar of active starter is the price of admission to genuinely great bread: open, moist crumb, a crackling crust, complex flavor, and better keeping quality than any commercially yeasted loaf — the acidity slows staling and naturally resists mold. It also earns its counter space beyond bread. And once your baking confidence is up, the same patience that built your starter transfers directly to pastry projects like a lattice-topped marionberry pie, where resting and chilling do the quiet work that fermentation does for bread.
Seven days from now — maybe ten, if your kitchen runs cool — you'll have a living culture that can bake for decades. Mix the flour and water tonight, and let the Northwest air do the rest.