Sourdough Starter Recipe

At the outset, the process of making your own sourdough starter can seem daunting, an inscrutable mix of microbial science and metaphysics. But if you understand the underlying concepts and follow the right steps, you will be rewarded with an active, well-developed starter that can raise bread.

One thing that can frustrate newcomers to the world of sourdough is the lack of concrete instruction. There's not one perfect roadmap to success, largely because you're dealing with wild yeast and bacterial cultures. No two cultures are the same, nor are the conditions under which they are cultivated. But here's the truth: Making a starter is not that hard. Follow the basic guidelines, use your senses, and your starter will live and thrive.

“You need to realize: It’s your starter. Your starter is going to need different things than my starter," says Kristen Dennis, a former scientist, baker, and face behind the popular Full Proof Baking Instagram account. She has devoted the last few years to teaching the finer points of sourdough bread. "If you live in San Francisco, you’re gonna have a different culture than I have here in Chicago, and a different culture than somebody in Singapore. So it’s a lot of subjective-ness and playing with it, and getting a feel for what your starter needs.”

Here's the process in a nutshell: Mix equal parts flour and water, then wait. After a while, mix some of that pasty stuff with a fresh dose of flour and water, and wait again. After repeating this process, over time this mixture will start to bubble, rising and falling with increasing predictability. After even more time (two weeks, or longer), you will have a mature sourdough starter—a stable community of microbes that can leaven bread. These microbes metabolize the flour's natural sugars to produce carbon dioxide, ethanol, lactic acid, and other desirable byproducts. These byproducts are responsible not only for raising bread, but also for providing that characteristic tangy flavor and light texture of sourdough.

People get really sentimental about their starters—so much so that they name them. And rightly so—a starter is a living ecosystem, so often thought to be shaped by some glossy, romanticized notion of “terroir.” Specifically, we could call it a microbial terroir—the net effect of flour, water, air, temperature, feeding, time, probability, and your own two hands. It’s important to remember that as much as we want to keep things tidy and sterile in the kitchen, we don’t cook in a vacuum. In fact, cultivating a sourdough starter depends on this imperfection.

In The Noma Guide to Fermentation (at Amazon), David Zilber writes about the Korean concept of “hand taste” (son-mat), “an irreplicable quality imbued by individual cooks to their food” or “the distinct character of a ferment imparted by its maker and the time and place in which it was made.” A sourdough starter is a perfect demonstration of “hand taste” at work. For this reason alone, no two starters you encounter will ever be the same. And that’s a beautiful thing.

How Do You Make a Good Sourdough Starter?

There's more than one right way to develop a strong, active starter. Based on my side-by-side testing of different flours and flour blends, many options work well. But flour is only one variable. You have latitude over several other factors as well, from fermenting temperature, to hydration level, to the feeding schedule and feeding ratio. Some variables are easier to control than others, and often will depend on your experience or equipment available.

While you don't have to understand the underlying science behind sourdoughs, it can help to learn a bit about what's actually happening on a microbial level. If you’re keen on that explanation, you can read about the science of sourdough starters. Still, there are a handful of important concepts to know and variables to understand. Let's take a closer look.

Key Sourdough Starter Concepts and Variables

Hydration Level

Making a starter involves mixing "equal parts flour and water." That’s technically for a 100% hydration starter. But starters can exist and thrive at varying hydration levels. For example, you could mix in half as much water to make a 50% hydration starter in the style of an Italian lievito madre. If this is your first time working with sourdough, I'd recommend beginning with a 100% hydration starter (equal parts water and flour by weight).

100% hydration starters are the most common type of starter to use. They are easy to maintain, easy to mix into a dough, and are easier for calculating additions to a bread recipe. Drier starters require more maintenance, are harder to mix into doughs, and the math is a little trickier. Meanwhile, wetter starters (over 100% hydration) eat through their supply of starches very quickly, requiring more frequent feeding and attention.

Starter Batch Size

It’s a common misconception that you need several pounds of flour to start and maintain your starter. Unless you plan on baking dozens of loaves at a time, it’s better—and less wasteful—to start small.

In theory, you could use exceedingly small amounts (even micrometers (sic), according to Kristen Dennis) of flour and water to build a starter, but if your batch is too small, it can become difficult to gauge how high your starter is rising. At the very least, you want a quantity that will fill the bottom of its container. That way, your starter can climb the sides and give you a clear visual indicator of its activity. For a small, narrow 1-cup jam jar, I've found that 10 grams each of water and flour is more than enough.

Feeding Schedule

As the microbes metabolize the flour's sugars in a starter, eventually those sugars run out. At this point, it is essential to feed or refresh the starter. Once your starter is mature, you'll want to feed it at peak—the maximum height your starter reaches in the container (usually doubled or tripled in volume). But in the nascent stages of a starter’s life, there is no way to know what peak is. Initially, it’s advisable to stick to a consistent feeding schedule while monitoring your starter's development. The most common schedule is to refresh every 12 or 24 hours.

Over time, your starter's cycle of peaking will become clearer, and you can adjust the feeding schedule accordingly. Just make sure to take your time. It's better to make changes slowly while observing your starter than to shift schedules at the first sign that it might be time to do so.

Aside from monitoring gains in height and volume, there are other signs your starter has peaked (or passed its peak). If your starter begins to smell more alcoholic and pungent than pleasantly sour, that's a sign of an excess build-up of ethanol and acids as microbes exhaust available sugars—an indication more flour is needed to replace those sugars. You should also feed your starter if it looks runny or soupy, a sign that it's become proteolytic, meaning enzymes and the buildup of acids (what sourdough expert Trevor Wilson calls “acid load”) have broken down gluten into a gooey mess. These conditions are not always ideal, because it can be difficult to use an increasingly acidic, proteolytic, and soupy starter past its peak for baking. But you can still make bread with it.

Feeding Ratio

Bakers use the convention X:Y:Z in reference to feeding, where X is the amount of starter, Y is the amount of flour, and Z is the amount of water. Typical ratios range from 1:1:1 all the way to 1:10:10. The higher the ratio, the more food you are providing to your starter, but the more you are diluting the population of microbes, which means it will take them more time to eat through the food and reach peak.

Increasing feeding ratios is a good way to keep your starter well fed and to adjust your schedule so that it doesn’t peak too early and become a proteolytic, puddly mess. But there’s a balance. “The idea is you always want to feed it right at peak. You increase the ratio to dilute out your inoculation a little bit,” says Kristen Dennis. “So instead of 1:1:1, maybe next time you try 1:2:2. And this should, in theory, slow it down a little bit."

In the beginning, it’s wise to start with a 1:1:1: ratio. Then, you can adjust that ratio later if your starter is peaking too quickly between feedings.

Discarding

In sourdough parlance, bakers refer to “discard” as a portion of fermented starter that you remove before feeding. Discarding keeps the total amount of starter in your container manageable. For example, say you had a starter that weighed 40 grams. If you didn’t discard any of it and fed it 1:1:1 it would weigh more than 120 grams after just one feeding session. If you continued in this fashion, eventually your starter would overflow out of the jar and you would have a giant, gooey mess on your hands.

Discarding also gives you precise control over the feeding ratio. You can weigh out exactly how much starter you want to “seed” with your flour and water. Because you control the seed amount, you effectively control how quickly your starter ferments, keeping the culture from becoming too acidic or weak in gluten structure.

It’s common to save the “discard” and use it for recipes like sourdough pancakes and crackers, and as a backup in case anything goes wrong with your primary starter. But in the beginning of a starter’s development, the mixture isn’t likely to have the sour flavor you’re after. At worst, it could have unpleasant smells and flavors, and even some unwanted pathogens that could make you sick. In the early stages before your starter is mature and stable, it’s advisable to throw your discard out (even more reason to keep your feeding amounts small).

Choice of Flours

Beyond feeding and scheduling, the first important variable in the development of a starter is flour. There are several good options, ranging from wheat flour to cereal grains. Here are some of the most common, with some notes on what they can contribute to a loaf.

• Unbleached All-Purpose Flour: The protein content of all-purpose flour varies between 9% and 12%, depending on brand. While any all-purpose flour can work, the higher the protein percentage, the closer the flour will be to bread flour, which can lead to more rise during baking. It's better to use unbleached white flour: The bleaching process depletes the potential population of microbes in flour, which can slow down the development of a starter.
• Unbleached Bread Flour: “The more protein you have, the more rise you will have,” says sourdough expert Kristen Dennis, and bread flour has the most, with a protein content ranging from 12% to 14%. This higher protein level gives the starter and bread doughs the ability to trap gas more effectively, resulting in that classic open crumb of a sourdough loaf.
• Whole Wheat Flour: Whole wheat flour includes the entire grain of wheat—including the bran, endosperm, and germ. Due to minimal processing, it is said to be packed with nutrients and potential microbes, providing faster fermentation for a starter. On the other hand, the inclusion of sharp bran can inhibit gluten development, which means your bread might not rise as high, retain its shape, or effectively trap gases.
• Rye Flour: Rye flour is another popular option for sourdough starters. Naturally rich in amylases, nutrients, and microbes, this cereal flour is known for faster, more efficient fermentation. Rye has a lower gluten protein content than wheat flour, which produces a more slack, sticky, and dense dough. But that doesn't mean it's a bad thing (100% Danish rye bread is proof that rye flour produces good bread). In the right hands, rye flour’s vast fermentative potential is a powerful tool that can result in tall, flavorful, and aesthetically pleasing sourdough bread.
• Flour Blends: You don’t have to use just one flour when making a starter. Many bakers use blends of flours to achieve starters with desired activity and flavor. Kristen Dennis uses a mix of 10% rye and 90% bread flours, which gets a boost of fermentative activity from the modest amount of rye. You could just as easily mix whole wheat with AP flour in a 50-50 blend, or any other number of combinations and percentages. If you do use a flour blend, it’s helpful to pre-mix a large batch of it to make your life easier when it comes time to refresh your starter.

It's also worth noting that you're not necessarily locked into a flour choice after you start. You can use whatever you have on hand (so long as it's not bleached flour), and then transition to another—assuming your starter continues to peak and be active. For example, you can get a starter going quickly with a combination of rye and whole wheat flours, then gradually switch to mostly all-purpose flour. But be aware that switching the flour in your starter can introduce additional layers of complexity that can be difficult to predict. It’s important to make changes like these slowly and incrementally, so you can observe their effects over a longer period of time.

Liquid Type

Most people use water in their starters. But it’s important to note that your local tap water might be chlorinated. Chlorine is inhibitory to yeast and bacteria, and in high enough concentrations will kill those essential microbes, effectively impeding fermentation. The best way around this? Use bottled or filtered water. Alternatively, leaving tap water out uncovered in a wide container overnight will allow that chlorine to evaporate over time. Keep in mind, though, that if your tap water contains chloramine (another antiseptic and microbial killer), then leaving it out on the counter won’t do much. In this case, carbon or reverse osmosis filtering are your best bets.

Some people advocate adding beer with wild yeast, such as Hefeweizen (which contains yeast sediment after bottling) to give their new starters a head start. Others steep grape skins into their water or use grape must, which are rich in lactic acid bacteria (LAB) and yeasts. And some opt for whey, banking on that added boost of LAB to inoculate their culture. But those are uncommon methods, and beyond the scope of this guide.

Temperature

Temperature has a significant impact on the development of your starter, since it influences the level of fermentative activity. Mature starters can survive and grow over a relatively wide range of temperatures (as low as 41°F/5°C, and as high as 113°F/45°C). But most people ferment at room temperature on their counter, even though ‘room temperature’ is an imprecise term. Ambient temperature in the middle of an Atlanta heatwave is considerably higher than room temperature in the dead of winter in Montreal.

The effective range for the development of a new starter (and maintaining it) lies between 70°F (21°C) and 80°F (27°C). In this range, yeast can grow steadily, and lactic acid bacteria can flourish. Based on several sources, keeping the temperature around 80°F (27°C) is optimal for reliable development early on. If held at higher temperatures (85°F/29°C and higher), undesirable microbes such as E. coli or Staphylococcus aureus can compete with yeast and LAB in a starter's early stages, resulting in off-putting odors, orange or red mold, and spoilage.

Assuming you have some degree of control over the temperature where your starter lives, you can and should play with this variable until you find what works best for you. For example, if your starter ferments at a faster rate than desired—peaking well before its next feeding—you can slow things down by lowering the fermenting temperature.

No matter what temperature you choose, make sure you can keep it consistent. I keep my starters in a cool (off!) oven with the light on, maintaining a steady temperature between 78°F (26°C) and 80°F (27°C) during the day. If you’re serious and exacting about your starter (and have the cash for it), then investing in a temperature-controlled proofing box, container, or starter proofer like the Goldie by Sourhouse is the best choice. The Challenger Fermentation Mat is another great option.

Keys to Success

The First Week Is a Wash

The first week—and perhaps even longer—in a starter’s development is the hardest, but maybe the most important period. During this time, you may observe rapid gains in height and sour flavors. But don’t be fooled: Until your starter predictably rises, falls, and gives consistent aromas over a period of days, it’s unlikely that it’s ready to use for baking. The culture is still normalizing, zeroing in on that proper balance of microbes.

Find the Peak, Feed at Peak

The best way to ensure a healthy and thriving starter is to feed at peak—the point at which yeast activity is high but the starter isn’t yet proteolytic and gluten-weakening. For instance, at a feeding ratio of 1:3:3 or 1:4:4, a healthy starter should peak in at most 8-12 hours. How do you spot the peak? There are certain visual cues: More than doubling or tripling in volume, some bubbles on the surface, a dimpled and uneven, slightly domed top, some lingering strength in the mixture. If your starter is alcoholic, pungent, soupy with small or weak bubbles, and there are visible streaks on the inner walls of the jar (a sign that the starter has already risen and started to fall), then the starter is past peak. Ultimately, finding the peak involves monitoring your starter over a number of days. Predictability is the name of the game. So it helps to take pictures, keep a journal, and use rubber bands to measure gains in height over time.

When in Doubt, Keep Going and Be Consistent

If you haven’t taken the hint already, there is no one-size-fits-all roadmap to making a successful starter. In my tests, my starters matured after about two weeks, but yours might take far longer. If your starter does not rise and fall predictably, or if it doesn’t smell sour after some period of time, don’t freak out. Just keep going. Overall, it helps to keep feeding times and temperature consistent and strict. Keep feeding, keep taking notes, and keep feeding again. Remember: Natural selection takes time.

How to Know Your Starter Is Ready

Say your new starter has matured after a couple weeks. It’s doubling or tripling in volume and smells overwhelmingly sour. How do you know if it’s ready to use? Many bakers swear by the “float test.” You place a small bit of your starter in a bowl of water. If it floats, it’s active, and if it doesn’t, then it’s not ready. But as Trevor Wilson explains in his 384-page tome Open Crumb Mastery, “The float test only tells you one thing for sure—that there is enough gas trapped in the starter to float in water. That’s it.” That doesn’t necessarily mean your starter will leaven bread effectively, since it could have been very slow moving in its gas development. According to Trevor, the float test is a fallacy.

Want a better indicator? Look for signs of vigorous fermentation. A healthy starter should triple, or even quadruple in volume in a short period of time under the right conditions (for example, 4-6 hours at 80°F/27°C, fed at 1:2:2). The starter should feature uneven dimples on its surface, evidence of a few big, sturdy, bubbles on the top, and should feel like bubbly whipped cream when you stir it. Most of all, this activity should be predictable and consistent every day. But in the end, the truth is that you won’t know if your starter is effective until you bake bread and track its performance over time and over successive bakes.

Maintenance and Beyond

Feeding

If you’ve done everything right, your starter will be active and hungry. Keeping your starter healthy involves sustained feeding. How often do you feed it, when do you feed it, and in what ratio? That largely depends on your schedule and some trial and error. The goal is to feed at peak, or as close to peak as possible. For example, if feeding 1:1:1 or 1:2:2, then a healthy starter usually peaks in 4 to 6 hours at a warm temperature (78-80 degrees). That means that you’ll need to feed your starter every 6 hours or so.

But in a 24-hour period, that’s not so practical. One way to feed less frequently is to keep your starter in a cooler place (around 72 degrees), slowing down fermentation slightly. Another way to slow down fermentation is to increase the dilution of flour and water relative to starter—feeding 1:3:3 or higher. If you wish to feed once per day, then your feed ratio must be considerably higher. But at least anecdotally, Kristen Dennis and I have both found that less frequently fed starters show slightly less vigorous activity than starters fed on a more frequent, lower-ratio schedule.

I like to feed twice a day: once every 12 hours at a ratio of 1:5:5, kept at 72 degrees. Following this schedule, my starter peaks every 12 hours. On the other hand, Kristen likes to feed three times a day, keeping her feeding ratios smaller.

Long Term Storage

There’s one issue with keeping a sourdough starter: If you’re not making bread every day (or fairly frequently), it doesn’t make sense to keep feeding it. You’ll just be feeding and discarding, burning through your valuable supply of flour. One common solution is to stick your starter in the fridge. The lower temperature will slow down fermentation to a near halt (but won’t stop it entirely). You can either store your starter just as it has peaked, or you can store it about an hour after feeding.

A starter will keep safely in the refrigerator for about a week (anecdotally, I’ve left my starter in stasis for as long as two months, and been able to build it back to peak activity—though I don’t advise this practice). To ‘revive’ your starter, let it come back to room temperature, observe its activity, smell, and consistency, then feed it 1:1:1. Gradually, you can ramp up the feeding ratio and schedule to build the starter back to proper activity for baking.

A Sample Feeding Schedule

There's no set schedule that will work for everyone, but it can help to see examples of what a feeding schedule might look like. Here is a table showing my own schedule and ratios over the two-week period that it took me to make a stable sourdough culture from scratch. I encourage you to keep similar records to help keep track of your own starter.

Time to Jump In

For such a seemingly simple process, there is no shortage of variables factoring in the development of a sourdough starter. Changing just one can have a profound effect on flavor, aroma, and fermentative power. But don't let that complexity stop you. After all, complexity is what makes cultivating a sourdough culture worthwhile. At the end of the day, here’s what you need to know: It’s all going to work out. To make a sourdough starter is to play the long game—to delay gratification. Natural selection takes time. But in the end, it happens.

The best thing to do is to just start. And if you’re ever in doubt, just keep going.