A sourdough starter is one of the most magical things you can keep in your kitchen—just flour, water, and a little care turn into a living culture that gives bread its rise, flavor, and character. But as special as starters are, they can also bring up a lot of questions, especially for new bakers. Every time I share about my starter, I get messages asking for help troubleshooting. That’s why I’ve put together this guide to help you identify and solve the most common sourdough starter issues—so you can feel confident and keep your starter thriving.
If you want to start your sourdough bread and bakes journey, you will need a sourdough starter. Here is my guide to create your very own:
or you can buy some of my sourdough starter here:
Before we dive in, let’s go over a few key things that will set you up for success. Let’s start by discussing some facts you must know about sourdough starters::
A sourdough starter is a colony of microorganisms: wild yeast and lactic acid bacteria.
They are literally “everywhere”, they are already in the jar, in the spatula, in the flour, in the water, in the air, so believe me when I say they will find their way into your jar.
Just like any living organism, your starter needs certain things to thrive. Just like you need to eat good food to feel your best, fresh air, protect yourself from intense heat and cold and make yourself cozy at the right temperature you prefer, etc, your sourdough starter needs you to:
Not let it go hungry too long. It gets hangry (hungry + angry) don’t we all?
Feed it good flour and filtered water, and just the right amount of it.
Remember to use lukewarm water for feedings. Never feed it cold water from your fridge filter (warm it up slightly) or super hot water that can kill your little colony.
Give it a good stir when mixing and then again later in the day to get some oxygen.
Keep it cozy. Wild yeast and beneficial bacteria thrive in warm environments.
Never put a new or young starter in the fridge. Wait at least 2 weeks or longer if you can for best results, keeping it at room temperature.
Put it away from sunny windows where the UV rays can destroy the beneficial bacteria.
Keep things clean. Clean the top of the jar after every feeding, use a clean spatula every time, remember to cover it loosely, and change the jar often.
Every single time, when I hear from someone who is struggling to create their own starter or even keeping alive one they bought, we find out they didn’t treat their starter like the very unique living organism it was.
Now, I also want you to know that sourdough starters are incredibly resilient, once they are well established, strong, and healthy. If you use cold water one day, it’s ok. If you fed it a few hours later, it’s ok. If you fed it before it had fully peaked, it’s ok. If you forgot it in the fridge too long, it’s ok. Just don’t do it all the time, all right? And as soon as you realize the mistake, try to be extra loving to your starter for a few days. It will bounce back just as happy as it once was. I promise.
Ok now for the troubleshooting of the most common sourdough starter issues:
No activity
A starter that isn’t rising well or reaching full maturity may be due to weak yeast activity or the balance between yeast and lactic acid bacteria (LAB) being off. Yeast relies on readily available sugars, broken down by enzymes like amylase from the flour. If the flour quality is poor or the environment is too cold, yeast metabolism slows down.
If you are not seeing bubbles after a few days, if the starter is not rising, it could mean a couple of things:
The colony of microorganisms is still small to consume the given amount of flour/water, metabolize it and produce CO2 gas as a result.
The temperature might not be ideal. You might have used cold water or you might be keeping it at room temperature the first few days when higher temperature was recommended.
→ My suggestions to solve this issue are:
Do not feed it again for 24-36 hours after last feeding and keep it warm, around 85F until you see some activity. In the warmer environment, whatever small colony of microorganisms you currently have will reproduce faster (more of them) and breakdown the available starch and proteins in the flour into sugars and amino acids they can use and metabolize faster, producing CO2, which you will be able to observe as bubbles, indicating activity.
Wait until the activity slows down and you see very few to no bubbles again, and then feed.
Ensure you’re using high-quality, strong flour with active enzymes that promote yeast growth. Consider introducing some whole wheat or rye flour to increase the enzymes.
If it’s sluggish, consider refreshing it with a higher feeding ratio (e.g., 1:4:4 or higher) to give it a nutrient boost.
Funky smell
If your starter has a strange smell (like sweet, cabbage-like or funky) instead of the pleasant tangy smell of a sourdough starter, is runny and foamy, and it goes completely flat if stirred, you might have an overgrowth of the Leuconostoc bacteria, commonly present in the early days of a new starter. It produces gas (CO2) and causes bubbling and rising, even though the colony of wild yeast, the one typically responsible for the development of CO2 gases during fermentation, is fairly small.
The bacteria is harmless and will eventually die off as the starter becomes more acidic by gathering more lactic acid bacteria (LAB) from the environment.
→ Continue to feed your starter as suggested and keep it warm and the starter could overcome this in as little as one day.
Flour Smell
If your starter smells strongly like raw flour, it may not be fermenting properly. This can happen if the starter is underfed or dormant, or if it’s too young and the microbial community hasn’t fully developed yet.
→ Increase feedings to every 12 hours and keep the starter in a warm environment. Using whole grain flour can also help by increasing microbial activity and providing more nutrients.
Too Runny and Bubbly on Top
A watery or overly bubbly starter may be a sign of too much hydration or imbalanced fermentation. A runny consistency can also indicate that the yeast has consumed most of the available sugars, and the starter is "hungry." It might be peaking and dragging faster than you think. This can be due to a change in the ambient temperature, using a flour with more enzymes that breakdown sugars faster, making them available for the microbes to easily consume.
→ Watch for it to peak and feed it more often, at a higher ratio to ensure it has enough food to get it to the next feeding. adjust the hydration ratio to make a thicker starter (e.g., 1:1:0.75, flour to water). This slows down fermentation and helps maintain a more stable structure. Be sure to feed it regularly to keep the yeast well- nourished and consider trying different flour types and controlling the ambient temperature.
Dark Liquid Forming On Top
Hooch is the liquid that forms on the surface of a sourdough starter when it hasn't been fed for a while. This liquid is a byproduct of fermentation and consists primarily of ethanol (alcohol) along with water and other fermentation byproducts which separate from the starter and collect on top.
This liquid can vary in appearance but is usually a grayish, brown, or sometimes even yellowish layer of liquid, sitting just above the starter.
Hooch is a clear indicator that the starter is starving, and the yeast is entering a survival mode. While it is harmless, its presence signals an imbalance in the microbial environment, primarily due to the lack of fresh nutrients. At this point, it’s more of a discard jar than a starter, but it can be brought back to health with several regular feedings.
Hooch can technically be stirred back into your starter, but I don’t recommend it. Since it’s highly acidic, mixing it in will make your starter more sour, weaken your dough, and slow down recovery. Instead, pour it off before feeding to help keep your starter balanced and healthy.
→ Regular feedings ensure that your yeast and LAB remain well-nourished, reducing hooch production and maintaining the right acidity for healthy fermentation.
The Risk of Bad Bacteria and Mold
While sourdough starters are generally resilient due to the acidic environment created by LAB, neglecting feedings increases the risk of contamination by bad bacteria and mold.
Bad Bacteria: Normally outcompeted by LAB, unwanted bacteria can gain a foothold when the yeast and LAB are weakened by a lack of nutrients. This can result in unpleasant odors, such as a rotten or spoiled smell, which is a clear sign of bacterial contamination. Healthy starters typically have a pleasant, tangy aroma due to the activity of LAB and yeast.
Mold: Mold is another danger when the starter is not regularly maintained. Mold spores, often visible as green, black, or pink patches, thrive in areas where moisture is present, especially on the surface of an unfed starter. Once mold has appeared, the starter must be discarded, as it is no longer safe to use.
Green and Black Mold: These are the most typical molds found in spoiled food and indicate significant contamination. These spores may appear fuzzy or powdery and should not be confused with harmless flour speckles.
Pink or Orange Mold: This is particularly dangerous and often associated with the harmful bacteria Serratia marcescens, which usually develops in starters that have been neglected or contaminated.
If you notice pink or orange discoloration, it's a clear sign that your starter has been compromised and must be discarded immediately.
Do not confuse mold with hooch, which is a harmless liquid that can form on top of the starter. Mold, unlike hooch, is typically fuzzy and patchy and signifies contamination that cannot be corrected by simply feeding the starter.
→ Keep the sides and top of the jar clean and try to use a fresh jar with every feeding, especially at the beginning of establishing your starter.
The Starter Was Successful, But Went Dormant
A previously active starter that becomes dormant may have been exposed to an overly cold environment or gone too long between feedings, causing yeast and LAB activity to drop.
→ Dormant starters can often be revived by giving them frequent feedings (every 12 hours) and keeping them at slightly warmer temperature (around 75-80°F). Add whole grain flour to increase enzyme and nutrient availability, which helps stimulate yeast activity. The starter should show signs of bubbling and rising after a few feedings.
Missed One Feeding
If you miss a feeding but no hooch or mold has formed, your starter should still be fine. The yeast and LAB will enter a slower metabolic state but remain viable.
→ Simply resume feeding as usual. The starter may take a bit longer to respond, but the microbial population should bounce back quickly.
Missed Multiple Feedings (No Hooch or Mold Yet)
Missing several feedings, especially over a few days, will cause the yeast and LAB to slow down significantly. The starter will become more acidic, and the yeast will produce less CO2.
→ If no hooch or mold has formed, discard and refresh with a 1:4:4 ratio or higher to dilute the built-up acidity and reintroduce food. Feed it every 12 hours until it regains its usual vigor.
Traveling for More Than a Week
If you're traveling for more than a week, leaving your starter unfed could cause it to go dormant, form hooch, or even spoil.
→ For longer trips, refrigerate your starter to slow down microbial activity. Before storing, feed it at a high ratio of 1:10:10 to ensure it has enough nutrients to last. When you return, discard and resume normal feeding to wake it up. If you’ll be away for several weeks, consider drying some of the starter as a backup or asking someone to refresh your starter. If it forms hooch, just follow the instructions above.
Starter Looks Great, But the Loaf is Coming Out Dense
If the starter looks healthy but the bread is dense, the issue may lie in the balance between yeast and LAB. An overly acidic starter can weaken the gluten, making the dough unable to trap gas effectively. Another cause could be underproofing the dough before shaping.
→ First, ensure your starter is actually mature (14 days+ of consistent rising), doubling or tripling in size before using it in the dough. Make sure you use it at peak only, when the yeast is most active. If the starter is overly acidic (indicated by strong sour smell, weak dough that won’t withstand stretch and folds or coil folds or pass the window pane test, go flat after shaping, and result dense after baking), refresh it with a higher ratio of flour to water (e.g., 1:5:5 or higher) to dilute the acidity. Feed it every 12 hours until it regains its usual vigor. Additionally, be mindful of proofing times to give the dough enough time to rise at least 30% before shaping.
Slow Fermentation in Cold Weather
In colder temperatures, the activity of yeast and LAB slows down significantly, which can lead to sluggish fermentation and poor starter performance.
→ Keep your starter in a warmer spot (at least 70°F). If your home is too cool, consider placing the starter in the oven with just the light on or using a proofing box. You can also insulate the starter jar by wrapping it in a towel or using a warming pad. Give it more time to reach peak before using it.
Starter Smells Like Nail Polish Remover
A nail polish remover or acetone smell indicates an imbalance in the microbial environment, typically caused by an overgrowth of acetic acid bacteria (which produce stronger acids).
→ Discard part of the starter and feed it with fresh flour and water at a higher ratio (e.g., 1:4:4 or higher). Try to keep it at a stable temperature, as fluctuating temperatures can stress the microbes and cause this imbalance.
Thick Crust on Top of the Starter
If the crust is thin and hasn't molded, you can remove it, discard it, and feed the starter as usual. To prevent this in the future, ensure the starter is covered loosely with a breathable lid (like a cloth or loose jar lid) to retain moisture while still allowing airflow. Additionally, controlling humidity by keeping the starter in a more humid environment or using a damp cloth can help maintain the proper hydration level and prevent the surface from drying out.
Starter Forms Liquid at the Bottom or Top (not dark Hooch)
In some cases, a starter might separate, with liquid forming at the bottom or top of the jar. This is often a sign of overhydration or too long between feedings.
→ Adjust the hydration level of your starter by adding more flour or reducing water in future feedings. Stir the liquid back in and monitor the consistency after your next feeding.
Starter is Rising and Falling Too Quickly
If your starter rises and falls too rapidly after feeding, it may be due to an excess of simple sugars, overly warm conditions, or too much yeast activity.
→ Try lowering the ambient temperature and feeding your starter a higher ratio of flour to water (e.g., 1:4:4 or higher) to slow down fermentation. You can also try a different type of flour with less enzymes, like all purpose flour.
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Caring for a sourdough starter doesn’t have to feel overwhelming—it’s all about understanding what your starter is telling you and knowing how to respond.
Remember, every starter has its own personality given by the flour you feed it, the conditions you keep it in, etc, and part of the joy is learning how to work with it.
With a little patience and these troubleshooting tips, you’ll always be able to bring your starter back to health and keep it strong for many bakes to come.
Happy baking, my loaves!
~ Maria
Questions or recipe requests?