14 Common Mistakes That Are Killing Your Sourdough Starter

Is there anything homier than a fresh loaf of sourdough, perfectly crusty and straight from the oven? That beautiful, browned exterior and soft, fluffy interior are ideally suited to pairing with cheese, using for sandwiches, dipping in soup, and making savory bread puddings. Plus, while sourdough bread does contain gluten, it has considerably less than many other types of wheat bread. Learning to make sourdough starter is, therefore, a fun and profitable challenge for any amateur chef.

Making it even more appealing is that sourdough takes on many characteristics of your home environment, enabling you to develop a signature bread. "Wild yeast adapts to its environment," explains Odette D'Aniello of Dragonfly Cakes, "so if you bake a lot of cinnamon rolls or ferment things like kimchi nearby, your starter might take on subtle flavor notes over time." This is why some bakeries have distinctly flavored breads.

Sourdough starter is an unusual bread ingredient, a live organism that you must feed and water every day. "A sourdough starter is an almost fantastic thing — a living, breathing substance that you can customize to produce many complex flavors," says Nathan Myhrvold of Modernist Cuisine and co-author of "Modernist Bread at Home." The outcome depends on many factors, such as temperature, flour type, feeding schedule, and longevity ... all of which can become mistakes if you're not careful. Accordingly, let's take a look at the top 14 errors you might be making with your sourdough starter.

The type of water matters. "Your sourdough starter is a living mixture of wild yeast and good bacteria, which work together to create that lovely, tangy flavor and airy texture," says Jill Weatherburn of Baking Mad. "Chlorinated water can interfere with this natural process by disrupting the yeast and slowing down fermentation."

It's not hard to avoid chlorine, though, says Caitlin Vincent of The Sourdough Baker. "A simple carbon filter, like a Brita, can remove most of the chlorine while keeping beneficial minerals," she explains. Something like the Brita UltraMax Large Water Dispenser ought to do it. "However, avoid using a filter or water source that is too good, such as distilled water or reverse osmosis water, which completely strips the water of beneficial minerals and most (if not all) microorganisms." You can also boil tap water for 10-15 minutes and cool before using. Or let tap water sit for 24 hours in a container without a lid so the chlorine dissipates naturally.

That said, there's no need to worry too much. The Modernist Cuisine team, in an effort to determine how much different types of water really mattered, tested five kinds. While chlorinated tap water did result in the slowest fermentation, it didn't noticeably affect the bread until higher levels of chlorine were reached. Water samples nearing the upper legal limits for chlorine did lend some bitterness to the bread, the team found.

Temperature is important. Using water that is too hot can noticeably change your final result. "We caution against using very hot water when making a sourdough starter because that could gelatinize the starch in the preferment, which would adversely affect the end result," Nathan Myhrvold says. "Anything hotter than 97 degrees Fahrenheit can harm the yeast and prevent the starter from developing properly," Jill Weatherburn agrees. "Lukewarm water is the best choice, as it provides the right conditions for the yeast to thrive without shocking it."

Keep in mind that the type and temperature of water matter not just on the first day of your sourdough starter, but also every day after that as you continue feedings. Myhrvold recommends temperatures of 75 degrees Fahrenheit in colder months, 60 degrees Fahrenheit in summer, and 70 degrees Fahrenheit in months with mild weather. You can use water that is warmer than this, he adds, but it will speed fermentation, so "the yeast in your starter will need more food during fermentation and storage."

Whatever you do, Caitlin Vincent says, keep the water temp under 110 degrees Fahrenheit to avoid endangering your starter, and keep its internal temperature below 100 degrees Fahrenheit. You can use an Alpha Grillers Digital Meat Thermometer or something similar.

There are many opinions about the best flour to use in your sourdough starter, but the true answer is that you can use a great number of them without issue. However, most experts agree that bleached flour is one to avoid. "Bleached flour creates similar issues as chlorinated water or overly filtered water," Caitlin Vincent says, because the bleaching process "removes or damages key nutrients and microorganisms that support fermentation. This can result in slow or weak fermentation or even prevent a starter from developing at all."

Vincent adds that lower-grade flours contain more of the enzymes that break down gluten, known as proteases. That means your starter will also break down more quickly. "A weakened starter can negatively impact the dough's structure, much like trying to build a house on a weak foundation," she says. Nathan Myhrvold adds that you want to use flours that arrive from the mill full of friendly microbes such as yeasts and lactic acid bacteria, which means no bleaching.

Because a sourdough starter is simply a mix of flour and water, many people assume that you can safely use just one kind of flour. And while it's not unsafe, it's better for the long-term health of your starter to use multiple types. "Using a variety of flours can add depth to the flavor of your sourdough, making it more complex and slightly tangier," Jill Weatherburn says. "While white flour is great for a strong, consistent starter, experimenting with different blends can enhance the final loaf's taste and texture."

Weatherburn adds that you should look for flours that will provide structure and support. A high-protein flour such as those geared toward making bread is always good. Try Gold Medal Premium Quality Unbleached Bread Flour or King Arthur Unbleached Bread Flour, for instance. "Some bakers like to mix in whole wheat or rye flour, as these contain more natural wild yeast and minerals, which can help the starter ferment more actively," she says.

Also, different types of flour lead to different flavors. "Durum flour will produce a starter that has a sweeter, lactic acid flavor," Nathan Myhrvold says. On the other hand, whole wheat and rye flour are more astringent. "Cultures made with chickpea, bean, or lentil flours will have a vigorous yeast environment but will not be very sour," he says.

Another of the most common sourdough starter mistakes, says Nathan Myhrvold, is adding nontraditional ingredients to your starter. "Some bakers are devoted to the idea that raisins, pineapple juice, or yogurt can accelerate a sourdough starter's development," he says. This is an idea that sounds plausible on the surface because these foods contain beneficial yeasts and sugars and may lower the pH of your starter to outcompete the bad microbes.

"Examined empirically, however, the theory falls apart," he says. The team at Modernist Cuisine ran experiments to see whether or not adding accelerants like fruits or water infused with fruit really benefitted the sourdough starter, and the answer was a resounding no. Those sorts of add-ins don't speed up fermentation. Plus, relying on different sugars at the beginning of the process versus down the road can confuse your sourdough starter and lead to negative results, the team found.

"Think of your starter like a pet," Odette D'Aniello says. "It needs regular feedings to stay alive and happy." Keep in mind that the point of a sourdough starter is to rise and to make bread rise as well. That means that during your daily routine of feeding your starter (where it hasn't yet become bread), you will also see a natural rise. Regular feeding is critical to keep this pattern going. "If you forget to feed it for too long, the yeast weakens, making it sluggish," D'Aniello says. "Stick to a routine, and if you know you'll be busy, stash it in the fridge to slow things down." This will help avoid mistakes that could lead to your starter's demise.

Regular feeding will help establish a strong and steady cycle of rising and falling, which you can rely on when baking your bread. Essentially, your starter needs predictability. "The healthy growth of yeast and bacteria depends on three key things: availability of nutrients, acidity, and temperature," Nathan Myhrvold says. "Because growth can happen exceptionally fast, species and strains that aren't adapted to a particular environment can quickly be overwhelmed and die out." Bottom line? "Your starter's maintenance routine ultimately determines the overall success of your bread," Caitlin Vincent says.

Both overfeeding and underfeeding your sourdough starter are common mistakes to avoid. You must make sure to feed your starter proper amounts in order to maintain a stable balance of yeast and bacteria, Caitlin Vincent says, adding, "This ensures the production of just the right amounts of alcohol, acid, and carbon dioxide —essential for flavorful, well-risen bread. A well-fed starter is more predictable and easier to work with, making bread baking more successful."

When underfed, starters build up too much acid, which can lessen the further growth of yeast and friendly bacteria, leading to weak dough and breads that don't rise. It also makes your starter too sour.

Overfed starters have their own problems. They make the ratio of flour and water to bacteria too high, causing dilution of the bacteria with each feeding. This weakens fermentation and slows down the establishment of your starter, leading to poor bread in the long term.

There exists a number of sourdough starter temperature mistakes, and if you want to get the best results, you must steer clear of them all. If an environment is too cold, your starter will slow down; too hot, and it ferments too quickly and becomes sour. This can also cause it to rise and fall too quickly, leading to collapse and inability to support your bread.

Store your starter someplace that consistently stays between 68 and 85 degrees Fahrenheit, Odette D'Aniello recommends. "A warm but not hot spot, like inside a turned-off oven with the light on, keeps things bubbling along nicely," she says. You can also keep it on top of the fridge, where heat will rise, or near the stove.

The good news is that you can use temperature to your advantage to encourage a sourdough starter in the direction you desire. Forgetting how much control they have is one of the more common mistakes home bakers make. For instance, you can control the sourness of your starter with temperature shifts. "Want a less sour starter?" D'Aniello says. "Keep it at a slightly warmer temperature, like 75-78 degrees Fahrenheit, and feed it more often to encourage yeast growth. Want a more sour flavor? Let it ferment longer at cooler temps (65-70 degrees Fahrenheit), and use whole-grain flours for more acetic acid production."

There are many ways you can contaminate a sourdough starter, causing it to get funky, stop fermenting, and die. Whoops. "Keeping your starter clean is just as important as feeding it, as any unwanted bacteria can quickly ruin all your hard work," Jill Weatherburn says. "Always use a clean jar, scrape down the sides with a small silicone spatula, and wash your hands before handling it to keep everything as hygienic as possible." The U-Taste Silicone Spatula Set might do the trick if you don't already have a few nice spatulas. Never use a tool that is dirty or has touched other fermenting foods.

Signs that your starter has become contaminated include pink, orange, or fuzzy patches, Weatherburn adds. These all indicate that your starter is done for, and you should try again. The good news is that once your starter gets going, you're unlikely to have to deal with contamination as long as you're careful. "Yeasts and lactic acid bacteria coexist so well because each can grow alongside the other and tolerate, to a certain extent, the other's defense mechanisms," Nathan Myhrvold explains. Therefore, all you have to do is feed them regularly to keep them healthy, and they will outcompete other, less desirable microbes. "Covering the jar loosely with a lid or cheesecloth allows the starter to breathe while keeping it protected from anything that could get inside," Weatherburn advises.

Make this your mantra: Do not eyeball the feeding of your sourdough starter. This is one of the mistakes that can definitely make it go off the rails and die. "Hydration levels matter more than you think," Odette D'Aniello says. "A super wet, liquidy starter of 100% hydration or higher will ferment faster but can be less predictable," she explains. This means you've added equal parts flour and water. On the other hand, she says, "a thick, doughy starter, like a 50%-75% hydration, ferments slower but is more forgiving."

That's not to say a starter with equal parts flour and water can't be healthy because it can. Indeed, says Jill Weatherburn, such a starter stays lively and bubbly, while dryer ones may not ferment properly. Starters that are too wet usually become runny and weak. Also, Nathan Myhrvold says, "The more liquid the starter, the more acidic the resulting bread." So if that's your goal, go for it. Either way, make sure to pay proper attention to your measurements, and adjust the hydration as needed.

You have to give your sourdough starter long enough to develop, yet rushing to use it as soon as you see a good rise is one of the most common mistakes for novice bakers. "A false rise in the first few days is normal," Caitlin Vincent says. "This happens due to early bacterial activity and doesn't indicate a mature starter." You can't rely on normal signs of maturity, she says, such as the presence of liquid floating on the top or bottom of the starter. The float test (whether a piece of starter floats in water) isn't reliable either.

"The best indicators of a healthy starter are consistent height increase to triple or quadruple in size between feedings and a proper pH balance, typically between 3.88 and 3.92 before feeding," she says. Using a pH reader can provide precise insight into starter health.

On the other hand, not using your starter soon enough also falls into the realm of common mistakes, though in this case, we're not talking about a matter of days or weeks, but rather hours. Why? If you've trained your starter properly, then it's on a consistent rise-fall schedule, and using it at different times of day will risk flavor differences.

"The longer you wait between when you last fed your starter and when you use it, the more acidic the flavor," Nathan Myhrvold says. "But there is no right or wrong level of acidity; it's a matter of personal preference, so experiment with different timings to learn what you like." If it's become too acidic in flavor, then use less starter and add commercial yeast in your dough instead: use between 0.3% and 0.4% of the total ingredient volume. Don't wait more than 18 hours after last feeding it, though, since "its leavening power will decline," he adds.

Somehow, home bakers have gotten it into their heads that you should periodically starve your sourdough starter, but this is another of the more egregious mistakes that can lead to sourdough death. Nothing should have to go hungry, right? We are not monsters. "Starters thrive when fed regularly, not when starved," Caitlin Vincent says. "Once established, it's a misconception that letting a starter 'go hungry' improves fermentation." Plus, if you need to let it go dormant, you can just put it in the fridge, not starve it.

If you need to avoid feeding your starter for short periods of time (such as a long weekend away), you can always slow things down with hydration, says Nathan Myhrvold: "Right before you go, feed the starter and make it stiff. That is, instead of mixing 100% water into the starter, add only 50% to 60% water," he explains. "Feed [it] as you normally would as soon as you get home, then feed it again 12 hours later." By the following day, he says, your starter should be ready to go again.

As it happens, you can freeze your sourdough starter when needed, so long as you have the right tools on hand. Portion it into easy-to-handle trays such as Amazon Basics Reusable Silicone Round Baking Cups or Large Silicone Ice Cube Molds, then pop it in the freezer for as long as needed.

Think your sourdough starter is bad? One of the biggest mistakes that can kill your starter is, well, to kill it on purpose. Don't throw away a starter until you're sure you can't save it. "Old starter?" Odette D'Aniello queries. "Try rye or whole wheat to revive it. If your starter has been neglected in the fridge for weeks and looks lifeless, a couple of feedings with rye or whole wheat flour can work wonders." The minerals and natural yeast contained in these whole grains will often give the starter the boost needed to bring it back to life, she says.

"The most important thing to remember is that making sourdough is a process that takes patience," Jill Weatherburn adds. Never assume your starter isn't working just because it isn't going gangbusters right out of the gate. "It's completely normal for a starter to take time to develop its full strength," she says. "As long as you feed it regularly and keep it in the right conditions, you'll soon have a starter that just keeps on giving."