A good sourdough starter looks deceptively simple: flour, water, and time. Yet anyone who has watched a new jar sit lifeless for a day—or suddenly triple in size and then collapse—knows that fermentation has its own rhythm.
The encouraging part is that you do not need expensive equipment or professional baking skills. You mainly need consistent feeding, a reasonably warm environment, and patience while the community of yeast and bacteria becomes established.
A sourdough starter is a fermented mixture of flour and water containing naturally occurring yeasts and lactic acid bacteria. When regularly fed with fresh flour and water, these microorganisms produce carbon dioxide and organic acids, allowing the starter to leaven bread while contributing the aroma, flavor, and acidity associated with sourdough.
King Arthur Baking describes flour and water as the basic ingredients needed to create a starter and recommends whole-grain flour as a useful starting point because of the microorganisms naturally associated with the grain.
This guide explains how to build a starter from scratch, what changes to expect each day, how feeding ratios work, how to tell when it is ready for bread, and what to do when something seems wrong.
What Is a sourdough starter?
A sourdough starter is essentially a living fermentation culture.
When flour is mixed with water, microorganisms naturally present in the flour and surrounding environment begin metabolizing available carbohydrates. Over time, a stable ecosystem develops containing yeasts and several types of acid-producing bacteria.
The yeast contributes carbon dioxide, which helps dough rise. Lactic acid bacteria contribute acids and flavor compounds that influence the bread’s aroma, taste, dough behavior, and keeping quality.
That is why sourdough differs from bread made only with commercial baker’s yeast.
Commercial yeast provides a concentrated and predictable source of yeast. A mature starter contains a more complex community of microorganisms and generally ferments dough more slowly.
What is actually inside a starter?
A healthy culture contains:
- Flour
- Water
- Naturally occurring yeasts
- Lactic acid bacteria
- Organic acids
- Carbon dioxide
- Fermentation byproducts
You do not need to add packaged yeast to establish a traditional starter.
You also do not need sugar, honey, grapes, yogurt, or other ingredients. Some starter methods use them, but flour and water are sufficient.
Starter, levain, and discard are not exactly the same
These terms often confuse new bakers.
| Term | What it means | Typical use |
|---|---|---|
| Starter | Your ongoing culture of flour, water, yeast, and bacteria | Maintained long term |
| Levain | A portion of starter deliberately built for a particular bake | Added to bread dough |
| Discard | Starter removed during feeding | Used in discard recipes or discarded |
| Ripe starter | Recently fed starter at or near peak activity | Bread making |
| Unfed starter | Starter that has consumed much of its available food | Maintenance or some discard recipes |
Some bakers use “starter” and “levain” interchangeably, but thinking of the levain as a temporary build makes many sourdough recipes easier to understand.
How to Make sourdough starter From Scratch
There are many successful methods, so do not worry if another baker uses slightly different quantities or feeding schedules.
The underlying process is the same: combine flour and water, allow fermentation to begin, then repeatedly retain part of the culture and feed it with fresh flour and water.
King Arthur Baking notes that starter methods can vary and that a consistent process matters more than following one supposedly universal formula.
For a practical beginner version, start small.
What you need
Use:
- 30 g whole wheat or whole rye flour
- 30 g room-temperature water
- A clean glass jar or food-safe container
- Digital kitchen scale
- Spoon or spatula
- Loose-fitting lid
A kitchen scale is particularly useful because flour can vary substantially when measured by volume. King Arthur likewise recommends weighing starter ingredients for better accuracy and consistency.
Why start with whole-grain flour?
Whole wheat and rye flour are popular for establishing new cultures because they provide plenty of nutrients and microorganisms associated with the grain.
King Arthur specifically recommends beginning with whole wheat or pumpernickel flour before transitioning to all-purpose flour if desired.
You can still maintain a mature culture with:
- Bread flour
- All-purpose flour
- Whole wheat flour
- Rye flour
- Mixtures of different flours
The flour you choose affects fermentation speed, consistency, aroma, and feeding behavior.
Day-by-Day sourdough starter Schedule
A new culture does not follow a perfectly predictable timetable. Temperature, flour, water, feeding frequency, and microbial activity all affect development.
Five to seven days is often presented as a starting timeline, but many starters require longer before they become consistently strong enough to leaven bread. King Arthur advises that a starter made from scratch generally needs about five to seven days before baking, while other sources commonly allow a longer maturation period when activity is inconsistent.
Day 1: Mix flour and water
Combine:
- 30 g whole-grain flour
- 30 g water
Mix until no dry patches remain.
The texture should resemble a thick batter or soft paste.
Scrape down the sides of the jar and loosely cover it. A starter needs protection from debris and insects, but the jar should not be sealed in a way that allows fermentation pressure to build unchecked.
Leave it somewhere around normal room temperature.
King Arthur uses roughly 70°F as a useful reference point and notes that colder temperatures slow starter development.
Day 2: Observe before reacting
You may see:
- No visible activity
- A few bubbles
- Slight expansion
- A floury smell
- A mildly fermented aroma
All of these can be normal.
If your starter suddenly becomes extremely bubbly on the second day, do not assume it is already mature. New cultures commonly go through an early burst of bacterial activity before settling into a quieter stage.
Keep 30 g of starter.
Add:
- 30 g water
- 30 g flour
Mix well and loosely cover again.
Day 3: Activity may slow down
This is where many people think their starter has died.
Yesterday it looked energetic. Today it barely moves.
That slowdown can be part of normal microbial succession while the environment becomes increasingly acidic and organisms better suited to sourdough begin dominating.
Continue feeding consistently.
Keep:
- 30 g starter
Feed:
- 30 g water
- 30 g flour
This is a 1:1:1 feeding ratio by weight: one part starter, one part water, one part flour.
Days 4 to 5: Look for repeatable fermentation
At this point you may notice more reliable bubbles throughout the mixture.
The aroma may evolve from raw flour toward:
- Yogurt-like
- Fruity
- Tangy
- Yeasty
- Mildly acidic
You may also notice a visible high-water mark showing how far the starter rose before falling.
Do not judge maturity from bubbles alone.
What matters more is repeatable rise after feeding.
Days 6 to 7 and beyond: Measure performance
Continue feeding once or twice daily depending on how quickly the culture consumes its food.
A vigorous starter should eventually:
- Rise significantly after feeding.
- Become filled with bubbles.
- Reach a peak.
- Flatten or dome slightly.
- Gradually fall.
King Arthur describes baking-ready starter as bubbly and capable of roughly doubling within about six to eight hours after feeding.
If yours still takes much longer, keep feeding it. The calendar matters less than its behavior.
Quick Takeaway: Do not decide that your starter has failed simply because it is not ready on day five or seven. A young culture is ready when its rise becomes strong and predictable, not because it has reached a specific birthday.
The Best Flour for Feeding a Starter
One of the most common questions is whether sourdough requires special flour.
It does not.
Different flours simply behave differently.
Whole wheat flour
Whole wheat is nutrient-rich and often encourages vigorous fermentation.
It can be especially helpful when:
- Starting a culture from scratch
- Reviving a sluggish starter
- Fermenting in a cool kitchen
Because the bran and germ remain in whole wheat flour, its nutritional profile differs from refined white flour.
Rye flour
Rye is another favorite among sourdough bakers.
It tends to ferment enthusiastically and can give a struggling culture a useful boost.
Even replacing a small percentage of white flour with rye can noticeably change starter activity.
Bread flour
Bread flour works well for maintaining starter and generally contains more protein than ordinary all-purpose flour.
It tends to produce a somewhat elastic culture.
All-purpose flour
All-purpose flour is perfectly suitable for routine maintenance.
Many bakers establish a starter with whole-grain flour and later maintain it with all-purpose flour because it is widely available and predictable.
King Arthur’s maintenance method, for example, uses all-purpose flour for routine feeding after establishment.
Do you need organic flour?
No.
Organic flour can work extremely well, but organic certification itself is not required for fermentation.
Choose fresh flour that has been stored properly.
What Water Should You Use?
Normal drinking water usually works.
King Arthur advises that ordinary tap water is generally acceptable unless it is so heavily treated that chemical odors are obvious.
If your culture repeatedly struggles and you suspect your water, try:
- Filtered water
- Bottled drinking water
- Water allowed to stand before use, where appropriate for the treatment method
Avoid very hot water because excessive heat can damage microorganisms.
Room-temperature or mildly lukewarm water is easier to work with.
Understanding sourdough starter Feeding Ratios
Feeding ratios look intimidating until you understand the notation.
A ratio such as:
1:1:1
means equal weights of:
starter : water : flour
For example:
- 30 g starter
- 30 g water
- 30 g flour
King Arthur uses this equal-parts-by-weight structure in its current maintenance method.
What does 1:2:2 mean?
It means:
- 20 g starter
- 40 g water
- 40 g flour
The larger feed provides more fresh food relative to the amount of existing culture.
What does 1:5:5 mean?
For example:
- 10 g starter
- 50 g water
- 50 g flour
A higher feeding ratio generally takes longer to reach peak fermentation because the microorganisms have a larger fresh food supply to work through.
This can be useful in warm kitchens or when you want the starter to peak later.
Why feeding ratios matter
Ratios let you control fermentation timing.
A starter fed 1:1:1 and one fed 1:5:5 may both be perfectly healthy, but they should not be expected to peak at the same time.
Temperature matters too.
A warm 1:5:5 culture might still move faster than a cold 1:1:1 culture.
That is why experienced bakers watch the starter rather than relying entirely on a clock.
Why Do You Have to Discard Starter?
Discarding seems wasteful at first.
But imagine keeping every gram of starter and adding an equal quantity of flour and water at every feeding.
The amount would grow exponentially.
Discarding controls the total quantity while maintaining a useful ratio between established culture and fresh food.
For example:
- Keep 30 g starter.
- Remove the excess.
- Add 30 g water.
- Add 30 g flour.
- Finish with approximately 90 g starter.
You now have a manageable culture instead of an ever-expanding bucket.
Can you use sourdough discard?
Yes, once your culture is established and healthy.
Discard can be incorporated into foods such as:
- Pancakes
- Waffles
- Crackers
- Flatbreads
- Pizza dough
- Muffins
- Cakes
King Arthur similarly recommends using discard in pancakes, waffles, cakes, pizza, flatbread, and related recipes.
During the earliest days of building a new culture, however, many bakers simply throw away the discard rather than cooking with it.
How Often Should You Feed sourdough starter?
The answer depends on where you store it and how often you bake.
If kept at room temperature
A starter living on the counter generally requires frequent feeding.
Once every 24 hours may work for some cultures, while highly active starters in warm environments may require more frequent feeding.
King Arthur’s current maintenance guidance uses roughly daily feeding for a countertop culture, with more frequent feeding when preparing a refrigerated starter for baking.
Watch how quickly yours peaks.
If it reaches maximum height and collapses long before the next feeding, adjust the feeding ratio or schedule.
If kept in the refrigerator
Refrigeration dramatically slows fermentation.
For people who bake occasionally, this is usually easier than daily countertop maintenance.
A common routine is:
- Feed the starter.
- Allow fermentation to begin at room temperature.
- Refrigerate it.
- Feed roughly weekly during long-term storage.
King Arthur recommends approximately weekly feeding for refrigerated starter.
You do not need to maintain a giant jar. Their smaller-starter method demonstrates that a culture can be maintained successfully with only about 20 g retained between builds.
What Temperature Is Best for a Starter?
Temperature is one of the biggest variables in fermentation.
Around 70°F, or roughly 21°C, is a useful reference point for maintaining and developing a starter. King Arthur uses approximately 70°F in its sourdough guidance and explains that cooler environments slow growth.
You do not need to hit an exact number.
The key principle is simple:
Warmer starter = generally faster fermentation.
Cooler starter = generally slower fermentation.
Avoid extreme heat.
Putting the jar directly against a strong heating element can create temperatures much higher than expected.
Better warm locations might include:
- A mild spot above the refrigerator
- A temperature-controlled proofing box
- A switched-off oven with the light used cautiously
- Another draft-free location with stable warmth
If you use an oven, leave yourself a reminder so nobody accidentally turns it on.
How to Tell When sourdough starter Is Ready
This matters more than the number of days you have been feeding it.
A baking-ready culture should show predictable strength.
Look for several signs together.
1. It rises substantially after feeding
Mark the starting level with:
- An elastic band
- Washable marker
- Tape
Then observe the rise.
A healthy mature starter commonly doubles, and some cultures may rise even higher depending on flour choice and consistency.
2. It rises on a predictable schedule
Consistency is more valuable than one dramatic rise.
If your starter doubles after one feeding but barely moves after the next three, it is still stabilizing.
3. Bubbles appear throughout the jar
Surface bubbles are useful, but bubbles distributed throughout the culture show that fermentation is happening internally too.
4. The texture becomes aerated
A ripe starter often looks webbed, fluffy, or sponge-like when stirred.
5. The aroma is pleasantly fermented
Expect aromas ranging from:
- Mildly sour
- Fruity
- Yogurt-like
- Yeasty
- Wine-like
- Slightly vinegary
A sharp smell does not automatically mean something is wrong.
6. It peaks within a reasonable period after feeding
King Arthur considers a starter ready for bread when it can roughly double within six to eight hours and appears bubbly and vigorous.
That is a more useful benchmark than simply saying “use it after seven days.”
Does the Float Test Really Tell You When Starter Is Ready?
The float test involves placing a small amount of starter into water.
If it floats, trapped carbon dioxide has made it sufficiently buoyant.
If it sinks, bakers sometimes interpret this as a sign that it is not ready.
The test can be useful, and recent baking guidance still presents it as a quick indicator when performed around peak rise.
But it should not be your only test.
Results can change depending on:
- Flour type
- Hydration
- How aggressively you scoop the sample
- Whether you knock gas out
- Whether the starter has already passed peak
A starter’s repeatable rise after feeding is usually the more meaningful measurement.
If your culture doubles reliably, has good bubble structure, and smells healthy, do not reject it solely because one spoonful sinks.
What Does Peak Starter Look Like?
Understanding the peak is one of the most useful sourdough skills you can learn.
Immediately after feeding, the mixture sits near its starting level.
Then:
- Fermentation accelerates.
- Gas accumulates.
- The starter expands.
- The top becomes rounded or domed.
- Maximum height is reached.
- The surface begins flattening.
- Eventually the culture falls.
A starter at peak activity is often ideal for naturally leavened bread.
King Arthur notes that a ripe culture appears expanded and bubbly, while a slightly concave top can indicate it has moved just beyond its peak.
Missing the peak by a few minutes does not ruin anything.
You are looking for a practical fermentation window, not a laboratory-perfect second.
Why Is My Starter Not Rising?
A sluggish culture is one of the most common beginner problems.
Usually, the starter is not dead.
Your kitchen is too cold
Cold dramatically slows microbial activity.
Try moving the jar somewhere slightly warmer.
The starter is still young
A new culture can take longer than a neat five- or seven-day schedule suggests.
Keep feeding it.
You are feeding too aggressively
Imagine a weak starter containing a small microbial population.
If you repeatedly dilute it with very large amounts of flour and water before it becomes active, visible fermentation may take much longer.
Use a moderate feeding ratio until the starter becomes stronger.
You are feeding too late
The opposite can happen too.
If your culture peaks quickly and then remains collapsed and hungry for many hours, increase the feeding ratio or feed more often.
Your flour may be slowing things down
Try replacing part of your regular flour with:
- Whole wheat
- Rye
Whole-grain flour is commonly recommended during starter creation because it can support vigorous fermentation.
Your water may be a factor
If everything else looks correct and your tap water smells strongly treated, test filtered or bottled drinking water for several feedings.
Why Does My Starter Smell Strange?
A starter’s smell evolves continuously.
Some odors are expected.
Acetone or nail-polish-remover smell
This often appears when the culture has become very hungry.
Feed it.
If the smell repeatedly returns long before your next scheduled feeding, adjust the ratio or frequency.
Strong vinegar smell
This can occur as acidity builds.
Again, it does not necessarily indicate spoilage.
Alcohol-like smell
Fermentation produces several metabolic byproducts, and alcoholic aromas can occur in hungry cultures.
Fruity or yogurt-like smell
These are common signs of fermentation.
A mature starter frequently develops a pleasant combination of fruity, lactic, yeasty, and acidic notes.
What Is the Liquid on Top of My Starter?
You may occasionally find grayish or brownish liquid over a neglected culture.
Bakers commonly call this hooch.
It tends to indicate that the starter has been sitting without enough fresh food.
You can often either stir the liquid back in or pour it off before feeding. King Arthur’s refrigeration guidance likewise says liquid on the surface can be drained or stirred back into the culture.
If the starter smells strongly alcoholic after sitting for a long time, several regular feedings usually restore activity.
When Should You Throw a Starter Away?
Sour aroma, alcohol notes, separation, or temporary inactivity are not by themselves reasons to discard a culture.
Visible contamination is different.
Discard the starter if you see signs strongly suggesting spoilage, such as:
- Fuzzy mold
- Unusual colored mold growth
- Pink or orange discoloration
- Obvious rotten contamination
Do not simply scrape mold off the top and continue maintaining the remaining culture.
When in doubt about genuine contamination, starting again is inexpensive: flour, water, and time are all you need.
How to Revive a Refrigerated Starter
A refrigerated culture can look sleepy when removed from storage.
That does not mean it has died.
Use this process:
- Remove the starter from the refrigerator.
- Retain a small portion.
- Feed it fresh flour and water.
- Keep it at room temperature.
- Wait for activity.
- Repeat feedings until the rise becomes strong and predictable.
King Arthur recommends feeding a refrigerated starter repeatedly at room temperature until it can double or triple within about six to eight hours before using it for bread.
A recently refrigerated culture may recover quickly.
A starter neglected for weeks or months may need several cycles.
Quick Takeaway: Do not judge a refrigerated starter by its first feeding. Judge it after several cycles of fresh food at room temperature.
How Much Starter Should You Keep?
Much less than many beginners assume.
There is rarely a reason to maintain several hundred grams unless you bake constantly.
A small culture reduces:
- Flour usage
- Discard
- Storage space
- Maintenance cost
For example, you can maintain:
- 20 g starter
- 20 g water
- 20 g flour
That produces approximately 60 g.
King Arthur publishes a small-maintenance method using 20 g each of ripe starter, water, and flour, demonstrating how little starter is actually required for ongoing baking.
When you need more for a recipe, simply build more.
Suppose you have 20 g starter but need roughly 200 g for baking.
Instead of keeping 200 g permanently, increase the feed before baking.
That approach is cleaner and produces far less discard.
How to Build Enough Starter for a Recipe
Never use every gram of your culture unless you have intentionally planned to rebuild it.
Keep a small seed amount.
For example, imagine your recipe needs 150 g ripe starter.
You could retain:
- 20 g mature starter
Then feed approximately:
- 75 g water
- 75 g flour
You now have about 170 g.
Once ripe:
- Use 150 g in your recipe.
- Keep approximately 20 g for future maintenance.
Exact quantities can be adjusted to your recipe and preferred feeding ratio.
The principle is more important than the numbers: maintain a small mother culture and build the amount needed for baking.
Starter Hydration Explained
Hydration refers to the amount of water compared with flour.
A starter containing equal weights of flour and water is called a 100% hydration starter.
For example:
- 50 g flour
- 50 g water
The water equals 100% of the flour weight.
This style is common because calculations are straightforward and the mixture is easy to maintain.
Liquid starter vs. stiff starter
Not every starter has equal flour and water.
A stiff starter contains proportionally less water.
A liquid starter contains more.
Different hydration levels affect:
- Fermentation speed
- Aroma
- Acidity
- Texture
- Dough calculations
King Arthur, for example, publishes bread formulas specifically built around stiff starter, illustrating that sourdough cultures can successfully be maintained at different consistencies.
Beginners do not need to experiment immediately.
A 100% hydration starter keeps the learning process simple.
Can You Change the Flour in an Existing Starter?
Yes.
You are not permanently locked into the flour used on day one.
You can transition gradually or simply begin feeding with another flour.
For example:
Current feeding: 100% whole wheat
Then:
- 75% whole wheat / 25% bread flour
- 50% whole wheat / 50% bread flour
- 25% whole wheat / 75% bread flour
- 100% bread flour
A gradual transition can make the change easier to observe, but established cultures are typically resilient.
You can also maintain a white-flour starter and occasionally add rye or whole wheat when you want stronger activity.
Can You Make Gluten-Free sourdough starter?
Yes, but it should be maintained entirely with suitable gluten-free grains if the goal is gluten-free baking.
Common options include:
- Brown rice flour
- Buckwheat flour
- Sorghum flour
- Millet flour
The fermentation principle remains similar, but texture and behavior differ from wheat-based cultures because gluten-free flours absorb water differently and do not form a gluten network.
For anyone avoiding gluten because of celiac disease or another medical requirement, ingredient sourcing and cross-contact control matter just as much as the starter recipe itself.
A conventional wheat sourdough starter is not gluten-free merely because it has fermented.
Common Beginner Mistakes
The biggest starter problems usually come from trying to control fermentation too aggressively.
Feeding by volume without accounting for weight
A cup of water and a cup of flour do not weigh the same.
That means “equal cups” does not create the same formulation as equal weights.
Use a digital scale when possible.
Changing the method every day
One day rye flour.
Next day all-purpose.
Then warm water.
Then cold water.
Then 1:1:1.
Then 1:5:5.
Constant changes make it impossible to understand what your culture is doing.
Pick a sensible system and observe it for several feedings.
Keeping far too much starter
Large cultures consume large amounts of flour.
Unless you bake commercially, maintaining 20 to 50 g of seed starter is usually enough.
Assuming bubbles equal readiness
Bubbles indicate fermentation.
They do not automatically indicate sufficient leavening strength.
Look for reliable rise.
Expecting the starter to follow the clock exactly
“Feed every 12 hours” is a useful schedule, but your culture cannot read it.
Its actual fermentation rate depends on:
- Temperature
- Flour
- Feeding ratio
- Hydration
- Microbial activity
Use the clock as a guide and the starter as the final authority.
Using a tiny airtight jar
Starter expands.
Use a container large enough to accommodate significant rise and keep it covered appropriately rather than packed into an undersized vessel.
A Simple Maintenance Routine That Actually Works
Once your culture is mature, maintenance becomes much easier than starter-building tutorials sometimes make it appear.
If you bake several times per week
Keep it at room temperature.
A practical routine is:
- Retain 20 to 50 g starter.
- Feed according to its fermentation speed.
- Let it rise and peak.
- Use ripe starter when baking.
- Feed the remaining culture.
Countertop cultures require regular attention because microorganisms remain active at room temperature.
If you bake occasionally
Refrigerate it.
A simple routine is:
- Keep a small starter.
- Feed it.
- Allow fermentation to begin.
- Refrigerate.
- Refresh approximately weekly during longer storage.
- Give it several room-temperature feedings before an important bake.
This general room-temperature-versus-refrigeration approach aligns with King Arthur’s current maintenance guidance.
How Long Can a sourdough starter Live?
Potentially for many years if it continues receiving flour and water and avoids contamination.
Starter cultures are maintained through continuous refreshment rather than because the original flour remains alive indefinitely.
Every feeding removes some old material and introduces new flour and water.
In that sense, a starter is less like a fixed ingredient and more like a continuously maintained microbial ecosystem.
King Arthur even describes its commercial culture as descending from a New England starter maintained since the 1700s, illustrating how starter lineages can persist through repeated feeding.
You do not need an ancient culture to make excellent bread, though.
A strong starter you created recently can perform perfectly well.
When Can You Finally Bake Bread?
Do not rush this step.
Your starter is ready for naturally leavened bread when it repeatedly behaves like a mature culture.
Look for:
- Consistent rising after feedings
- Roughly doubling within several hours under suitable conditions
- Plenty of internal bubbles
- Predictable peak and fall
- Pleasant fermented aroma
- Several consecutive strong feeding cycles
King Arthur’s guidance uses doubling within roughly six to eight hours as a useful readiness benchmark.
Once your sourdough starter reaches that stage, feed it, wait until it approaches peak activity, measure the amount required by your bread formula, and keep a small portion behind for your next bake.
The biggest lesson is not a particular ratio or number of days. It is learning to read the culture in front of you.
Flour matters. Water matters. Temperature matters. Feeding ratios matter. But consistency matters most.
Keep the culture small, feed it according to its actual fermentation speed, watch how high it rises rather than chasing bubbles alone, and give a young starter enough time to become reliably strong. Once that rhythm becomes familiar, maintaining a sourdough starter becomes one of the simplest parts of sourdough baking.