To build a starter, mix flour and water, keep it loosely covered, and refresh it with measured portions. Allow roughly a week or longer; a new starter is ready when repeated feedings produce a predictable rise, not simply when it first bubbles. Whole-grain flour is a useful starting choice. Do not save early-build discard for food, taste raw starter, or try to rescue a culture with mold or pink or orange discoloration.
A sourdough starter is a culture of yeasts and bacteria maintained by regular additions of flour and water. It can supply both leavening and flavor for bread. You can cultivate one at home without adding packaged yeast.
Choose one feeding method and keep a record of what you do. The methods below differ in batch size, hydration and schedule; their quantities should not be mixed together. The first follows King Arthur’s published small-batch method. The second outlines the larger build in Ken Forkish’s Flour Water Salt Yeast.
A day-by-day schedule tells you when to feed, but it cannot promise that your culture will be ready on a particular date. Temperature, flour and the developing microbial community all affect progress.
Try It Yourself
The Starter Clock
Record feeding weights, temperature and changes in your starter's height as the culture develops.
Open ToolWhat You Need
- Flour: Whole wheat or whole rye for the initial mix, plus the white flour specified by your chosen method.
- Water: Safe drinking water. Ordinary tap water usually works. Leaving it out for an hour is not a dependable treatment for every disinfectant: EPA notes that standing does not remove monochloramine. If you want to change the water, use suitable bottled water or a filter rated for the substance you intend to remove.
- A clean container: Food-grade plastic, glass or another nonreactive material, with enough space for expansion. A one-quart container works for the small method; the Forkish batch needs a much larger tub.
- A scale: Weigh the retained culture as well as the fresh flour and water. See our kitchen scale guide.
- A thermometer: Check the actual temperature where the container sits. Avoid unmonitored warm appliances and locations where someone could accidentally turn on an oven.
Wash hands and utensils before handling the culture. Keep it loosely covered so gas can escape while the cover limits contamination. Colorado State University Extension advises against tasting raw starter: flour is not a ready-to-eat ingredient.
Method 1: A Small Flour-and-Water Build
These quantities follow King Arthur’s starter recipe, whose small-batch version uses 50 g portions.
| Stage | Retain or start with | Add | Interval |
|---|---|---|---|
| Day 1 | Empty container | 50 g whole wheat or whole rye flour + 50 g water | Rest about 24 hours |
| Day 2 | 50 g mixed starter; discard the rest | 50 g unbleached all-purpose flour + 50 g water | Rest about 24 hours |
| Day 3 onward | 50 g mixed starter at each feeding; discard the rest | 50 g unbleached all-purpose flour + 50 g water | Repeat roughly every 12 hours |
Mix thoroughly and loosely cover each time. Start around 70°F; adjust water temperature to the room rather than using hot water. Each refreshment from day 2 makes 150 g of culture. Equal total flour and water weights give 100% hydration.
Mark the height after feeding. Continue the routine beyond the first week if needed, until repeated feeds produce a bubbly starter that reliably doubles in roughly 6–8 hours under these conditions. An early burst of gas is not enough on its own.
Method 2: Forkish’s Larger Whole-Wheat Build
Forkish’s Flour Water Salt Yeast uses a much larger culture. The quantities below describe that method, with readiness determined by activity rather than the day number. The warm-water targets belong to this particular routine; use a thermometer and take account of your kitchen conditions.
Day 1
Combine 500 g whole wheat flour and 500 g water at 90°F. Mix thoroughly in a large container (12-quart is ideal — the culture expands significantly). Loosely cover the container to limit contamination while allowing gas to escape.
The first mix weighs 1,000 g. Choose a tub that leaves ample headroom for expansion; the one-quart jar used for the smaller method is not suitable here.
Day 2
Discard three-quarters of the mixture. Add 500 g whole wheat flour and 500 g water at 90°F. Mix well, cover.
Day 3
Same as Day 2. Aroma and activity may change as the culture develops. A changing smell is not proof of readiness. Check for the contamination signs described below at every feeding.
Day 4
Reserve only 200 g of the culture (discard the rest — yes, it’s a lot of flour). Add 500 g whole wheat flour and 500 g water at 90°F. Watch for bubbling and expansion, recognizing that development may take longer than this schedule.
Day 5
Discard all but 150 g. Now transition to the maintenance feeding: 400 g white flour + 100 g whole wheat flour + 400 g water at 85°F. Once established, the routine retains 100 g mature starter with those same flour and water additions. A new culture may need further feedings before it raises bread reliably.
The maintenance feed contains 80% white flour and 20% whole-wheat flour in the added flour. Adding 400 g water to 500 g flour gradually moves the culture toward 80% hydration; the first feed from a 100% hydration seed is not exactly 80%.
The Early Rise and Quiet Period
A young starter may show a burst of activity and then become quiet. Its microbial population is still changing. Continue the chosen routine, observing the condition of the culture rather than assuming either success or failure from one day’s height.
Do not keep adding larger and more frequent feeds simply because a new starter is quiet. Check your weights and temperature, and give it time to respond. There is no universal day on which every starter becomes a stable, effective leaven.
Signs Your Starter Is Ready
For the small method above, look for repeated doubling in roughly 6–8 hours after feeding, bubbles throughout, and a pleasantly sour or yeasty aroma. Other feeding ratios and temperatures can produce a different time to peak.
A sharp alcoholic or solvent-like aroma can indicate that the routine needs attention, but smell alone does not identify an exact compound concentration. One sluggish feeding also does not prove the culture is dead.
Discard the entire culture for any mold or pink or orange discoloration. Do not scrape off the surface and reuse the rest. Clean the container thoroughly before restarting. A putrid or otherwise abnormal odor is also a reason to discard; do not assume every unpleasant smell is normal simply because the starter is young. King Arthur’s troubleshooting guidance distinguishes contamination from ordinary hooch.
The Float Test Has Limits
A spoonful floats when enough gas is trapped in it to make it buoyant. That is not a reliable go/no-go test for maturity: King Arthur’s direct comparison found that an under-ripe starter could float. Watch the rise over the feeding cycle and follow the cues in your bread recipe.
Do You Need Commercial Yeast?
No packaged yeast is needed for these flour-and-water builds. If a bread recipe calls for both sourdough and commercial yeast, add the latter to the final dough as instructed.
Adding baker’s yeast changes the inoculum, but it is not a universal law that any tiny addition will permanently displace every other yeast. Saccharomyces cerevisiae, the species used for baker’s yeast, is also common in sourdough communities. A culture’s composition depends on strains, conditions and interactions over time.
Storage and Revival
Once the culture is established, choose a maintenance routine that fits your baking. A room-temperature starter needs regular feeds; a refrigerated starter ferments more slowly and can go longer between them.
King Arthur’s maintenance guide gives an equal-weight routine with twice-daily room-temperature feeds or weekly feeds during refrigeration. That is one practical schedule, not a guarantee for every flour and temperature.
Before a bake, allow enough time for room-temperature refreshment and a reliable rise. A starter that has been neglected for weeks may take longer to recover than one fed recently. Two feedings are not a universal reset. Inspect for contamination before trying to revive it.
Temperature: Measure the Culture’s Conditions
Around 70–78°F is a useful starting range for the small-batch method. Warmer conditions generally speed fermentation within the culture’s workable range; colder conditions slow it. Neither a kitchen temperature nor a calendar can precisely predict the day it will be ready.
An oven light can make a confined space much warmer than expected. Measure the temperature, and protect the starter from accidental oven use. A stable room-temperature spot is preferable to an unmonitored hot location. The temperature of the water you add is also different from the final temperature of the flour-water mixture.
The Microbiology, Briefly
For the fuller explanation, see sourdough starter science.
Yeasts contribute carbon dioxide and ethanol; lactic acid bacteria contribute acidity and other metabolites, and some also make gas. The species and strains differ among starters.
One important distinction concerns sugar use. Fructilactobacillus sanfranciscensis can use maltose. Many sourdough Kazachstania humilis strains cannot; they use other sugars, including glucose. Saccharomyces cerevisiae can use maltose as well as glucose, depending on the strain and conditions. A controlled study of sourdough isolates compared maltose-negative K. humilis with maltose-positive S. cerevisiae and found that their interactions with bacteria were more complicated than simple mutual cooperation.
Geography is not a reliable recipe for a particular starter. In a study of 500 household starters, location was a poor overall predictor of community composition. Some geographic associations existed, so this does not mean location has no influence. You do not need to live in San Francisco to maintain an effective sourdough culture.
Which Flour Should You Use?
Whole wheat or whole rye is a practical choice for the initial mix. Neither is guaranteed to be the best in every kitchen. An all-purpose-flour starter can also work, and flour choice changes texture and behavior as well as the supply of nutrients and microorganisms.
For the small method, use the unbleached all-purpose flour specified in the recipe. For the Forkish method, use its white-and-whole-wheat mixture. Following one method consistently makes it easier to interpret changes than repeatedly switching flour, hydration and temperature together.
What to Do with Discard
Throw away the discarded portions from the initial build until you have a healthy, established culture. Do not collect the first few days’ mixture for pancakes or other food. King Arthur’s discard guidance specifically advises waiting until the starter is established before saving discard.
After that, sound discard can go into recipes designed for it. Store it refrigerated if you are not using it that day, and cook it as the recipe directs. Never use contaminated discard or taste it raw.
Discard is not necessarily dead or incapable of leavening. Its activity varies with feeding history; some bread recipes deliberately use unfed starter. Follow a recipe developed for that condition rather than assuming it behaves exactly like ripe, recently fed starter.
Transitioning to Your First Bake
Once feeds repeatedly produce a reliable rise, plan the refreshment so your starter reaches the maturity called for in the bread recipe. Reserve enough culture to maintain for the next bake.
Use your observations to refine the schedule: record the feeding ratio, temperature and time to peak. A first loaf teaches you more than a claim that every starter will be ready after the same number of hours.
For your first bake, start with our beginner sourdough bread guide. Once you’re comfortable, graduate to sourdough country bread.
For everything about ongoing feeding, timing, and maintenance, see our complete sourdough feeding schedule guide. If your starter stops cooperating, see sourdough starter not rising.
Frequently Asked Questions
- How long does it take to make a sourdough starter?
- Allow roughly a week or longer. Some cultures take several weeks, depending on flour, temperature and feeding. Look for reliable expansion over repeated feeds; a single early rise or a specific day number does not establish readiness.
- What's the best flour for a sourdough starter?
- Whole rye and whole wheat are useful starting choices, but neither is universally best. All-purpose flour can also work. Follow the flour and water proportions in one documented method, then learn how that culture responds.
- Do I need to buy a sourdough starter?
- No. You can cultivate one with flour and water. A mature purchased culture can save the initial development time, but it still needs care. Its place of origin does not guarantee a particular flavor or performance in your kitchen.
- Why does my new starter smell bad?
- Aroma changes as a young culture develops, but do not dismiss every odor as normal. Discard the entire starter for any mold, pink or orange discoloration, or a rotten or otherwise abnormal smell. An alcoholic smell can occur during fermentation and does not by itself measure contamination or readiness. Never taste raw starter to check it.
- Can I use all-purpose flour for my sourdough starter?
- Yes. The small-batch method here uses unbleached all-purpose flour after an initial whole-grain mix. Use the specified weights and track its rise. Changing flour can change consistency and timing.
