You’ve seen the photos. Those gorgeous, blistered loaves with the "ear" sticking up and a crumb that looks like a lace doily. It’s tempting to think it’s some kind of dark magic or a secret passed down by monks in the San Francisco hills. Honestly? It’s just fermented flour and water. That’s it. But if you’re looking into how to make sourdough starter from scratch, you’ve probably realized the internet makes it sound way harder than it actually is. People treat their starters like high-maintenance pets. They name them. They buy expensive jars. They panic if they miss a feeding by twenty minutes.
Stop.
Sourdough is remarkably resilient. It is literally a colony of wild yeast and lactic acid bacteria (LAB) that wants to live. You aren't "creating" life so much as you are creating an environment where the good stuff thrives and the bad stuff dies off. If you follow the science—not the influencers—you’ll have a bubbling, tangy culture in about a week. Maybe ten days if your kitchen is chilly.
Why your first attempt might have smelled like feet
Let's get one thing straight: day three is a lie. Around day three of learning how to make sourdough starter from scratch, your jar will likely explode with bubbles. You’ll think you’re a natural. Then, you’ll take a sniff and realize it smells like a gym locker or old cheese. This is the "false rise."
💡 You might also like: The Montana Bill of Sale: Why Getting It Wrong Could Cost You Your Title
A study published in Applied and Environmental Microbiology confirms that in the early stages of a new starter, various bacteria like Leuconostoc and Enterobacteriaceae take up residence. These guys produce gas, but they aren't the yeast you want. They’re the "bad" bacteria that can’t handle acidity. As you keep feeding the starter, the environment becomes more acidic. This acidity eventually kills off the stinky bacteria and allows Saccharomyces cerevisiae (wild yeast) and Lactobacillus to take over. If your starter stops bubbling on day four and smells weird, don't throw it out. It’s just the "changing of the guard." Keep going.
The gear you actually need (and what’s a waste of money)
You don't need a $50 "sourdough kit." You really don't.
Find a wide-mouth glass jar. Glass is better because you can see the bubbles and the "hooch" (that dark liquid that sometimes forms on top). A Pint-sized Mason jar works, but a Weck jar or a simple 1-quart deli container is even better because they don't have threads that get gunked up with dried flour. Dried sourdough starter is basically cement. Seriously. If you let it dry on a spoon, you’ll need a chisel to get it off.
You need a scale. This is non-negotiable. Measuring flour by "cups" is a recipe for disaster because one person’s cup of flour can weigh 120 grams while another’s weighs 160 grams depending on how packed it is. In sourdough, ratios are everything. Use a digital scale. They cost fifteen bucks.
The Flour Debate
- Whole Rye Flour: This is the "cheat code" for sourdough. Rye is packed with nutrients and amylase enzymes that break down starches into sugars that yeast love. If you use rye, your starter will likely be active much faster.
- Whole Wheat Flour: A great runner-up. It has the bran and germ, which carry the wild yeast from the grain itself.
- All-Purpose Flour: It works, but it's slower. If you’re using bleached flour, you’re making it harder for the microbes to survive. Use unbleached at the very least.
The step-by-step reality of how to make sourdough starter from scratch
Let’s get into the dirty work. We aren't going to use a "perfect" schedule because your kitchen temperature isn't a laboratory.
Day 1: The Inauguration
Mix 50 grams of whole rye or whole wheat flour with 50 grams of lukewarm water. Aim for about 80°F if you’re being precise. Stir it until no dry flour remains. It’ll look like thick paste. Cover it loosely—you want gases to escape—and put it in a warm-ish spot. 70-75°F is the sweet spot. Now, walk away. Leave it for 24 hours.
✨ Don't miss: Craftsman Weed Eater Electric: What Most People Get Wrong About Performance
Day 2: Nothing is happening
You probably won't see much. Maybe a tiny bubble. That’s fine. Don't feed it yet. Just stir it vigorously to introduce some oxygen and let it sit for another 24 hours. Some people insist on feeding every day from the start, but if the microbes haven't started eating yet, you're just diluting the colony you're trying to build.
Day 3: The Stink Begins
Now we start the "discard and feed" cycle. Take a fresh jar (or clean the old one). Put 50 grams of your "starter" into the jar. Throw the rest in the trash. Add 50 grams of unbleached all-purpose flour and 50 grams of water. Mix. This is a 1:1:1 ratio.
Days 4 through 7: The Grind
Repeat the Day 3 process every 24 hours. You might see that "false rise" we talked about. You might see nothing. You might see a layer of liquid on top. That liquid is "hooch," and it just means your starter is hungry. Pour it off or stir it in—it doesn't really matter. If you see fuzzy mold (green, black, or bright pink), that’s the only time you should toss it and start over.
Temperature: The silent variable
Most people fail at making sourdough starter because their house is too cold. Yeast is sleepy at 65°F. If your kitchen is chilly, your "7-day" starter might take 14 days.
Try putting your jar on top of the refrigerator or inside an oven with only the oven light on. Be careful, though—some oven lights get surprisingly hot and can cook your starter. You want it warm, not toasted. If you're struggling, check your water. If your tap water is heavily chlorinated, it might be inhibiting growth. Let your water sit out in an open container overnight to let the chlorine dissipate, or just use filtered water.
✨ Don't miss: Why the White Feather Cocktail Dress is Taking Over Your Feed Right Now
How do you know it’s actually ready?
Don't trust the calendar. Trust the bubbles.
A mature starter should double in volume within 4 to 6 hours after being fed. It should smell "yeasty" or "fruity"—sort of like a mild beer or yogurt. If it still smells like vinegar or gym socks, it needs more time.
The "Float Test" is a classic trick, though it’s not foolproof. Drop a teaspoon of your active starter into a glass of water. If it floats, it's full of carbon dioxide and likely ready to bake. If it sinks, it either isn't active enough or you accidentally popped all the bubbles when you scooped it out.
Why "discarding" feels so wrong (and why you have to do it)
New bakers hate throwing away half their starter. It feels wasteful. But think of it this way: if you don't discard, and you keep adding 100g of flour/water every day, within a week you’ll have a gallon of starter and you’ll need a bathtub to hold it.
The microbes need a high ratio of fresh food to "population" to stay healthy. Once your starter is established, you don't have to throw the discard away. You can make pancakes, crackers, or waffles with it. There are entire cookbooks dedicated to "sourdough discard" recipes because that tangy, fermented flour is flavor gold.
Common myths that need to die
- "You need to catch wild yeast from the air." Technically, most of the yeast in your starter comes from the flour itself, not the air. The microbes are already on the grain.
- "You can't use metal spoons." This is an old wives' tale from back when spoons were made of reactive metals like copper or tin. Stainless steel is perfectly fine.
- "Sourdough is gluten-free." Nope. It’s lower in fructans and some people with sensitivities find it easier to digest because the long fermentation breaks down some of the proteins, but it is definitely not safe for Celiacs.
Maintenance: The "set it and forget it" phase
Once you’ve successfully figured out how to make sourdough starter from scratch, you don't have to live in your kitchen. If you aren't baking every day, put that jar in the fridge.
A cold starter only needs to be fed once a week. Some people (myself included) have left their starter in the back of the fridge for a month. It’ll look grey and gross, and it’ll have a thick layer of black hooch on top. Don't panic. Pour off the liquid, scrape away the grey top layer, and take a small amount of the "gunk" underneath to start a new feeding cycle. Within two or three feedings, it’ll be back to its bubbly self.
Actionable Next Steps
If you're ready to start today, here is exactly what you should do in the next ten minutes:
- Clear a spot on your counter that isn't in a direct draft or under an AC vent.
- Grab a digital scale and a clean glass jar. Forget the volume measurements; they will fail you.
- Mix 50g of Whole Rye flour with 50g of room temperature water. Rye is the most reliable "starter" fuel because of its high nutrient content.
- Mark the level with a rubber band around the outside of the jar so you can actually see when it starts to move.
- Set a recurring alarm on your phone for the same time every day. Consistency in the first week is what builds the microbial strength needed for a great loaf.
Once you have that bubbling jar of life, your next move isn't just baking bread—it's learning how to read the "strength" of your starter to timing your bulk fermentation. But for now? Just get the flour wet.