# How to Make a Sourdough Starter From Scratch: A Day-by-Day Guide Source: https://fermentnest.com/blog/how-to-make-sourdough-starter-from-scratch Published: 2026-10-30 Publisher: Ferment Nest A sourdough starter is a mix of flour and water that has been colonized by wild yeast and lactic acid bacteria from the flour, the air and your hands. You do not need to buy anything special to begin: a jar, a spoon, flour, water and a little patience are enough. Most starters take roughly one to two weeks to become active and predictable, though kitchen temperature and flour type change the pace. This guide walks through each stage, explains which smells and bubbles are normal, and shows how to tell when your starter is strong enough to bake with. ## What you need before you start The ingredient list is short. You need flour, water and a clean container. Whole wheat or whole rye flour tends to wake up a new starter faster than refined white flour because it carries more of the grain's natural microbes and nutrients, so many bakers begin with whole grain and switch to a mix or white flour later. Unbleached flour is usually recommended because bleaching can interfere with microbial activity. For water, use something free of strong chlorine if your tap water smells heavily of it. Letting a jug of tap water sit uncovered for a few hours, or using filtered water, is a common workaround. For the container, a wide-mouth glass jar of about a quart works well because you can see the bubbles and the rise. A kitchen scale makes feeding far more consistent than measuring cups, and our guide to kitchen scales for fermenting covers the options. [See kitchen scales for fermenting](https://fermentnest.com/best/best-kitchen-scales-for-fermenting) ## Day one: mix the first batch Combine equal weights of flour and water in the jar, for example 50 grams of whole wheat flour and 50 grams of water, and stir until no dry flour remains. The mixture should look like a thick paste or a very thick pancake batter. Scrape down the sides so they do not dry into crust, cover the jar loosely so gas can escape, and leave it at room temperature. A kitchen that sits somewhere around 70 to 78 degrees Fahrenheit is generally comfortable for starters. Cooler rooms slow everything down, and warmer rooms speed it up. If your home is cold, a spot on top of the refrigerator or inside an oven with only the light on can help, though you should check the temperature rather than assume it. A stick-on thermometer or a small probe thermometer takes the guesswork out. ## Days two to four: expect quiet and odd smells On day two you may see a few bubbles, or you may see nothing at all. Both are normal. Feed the starter by discarding most of it, keeping about a tablespoon or 20 to 50 grams, and mixing it with fresh flour and water in equal weights. Discarding keeps the amount manageable and makes sure the remaining microbes have plenty of fresh food. Around days three to five many starters go through a confusing phase. Early bubbles can come from bacteria that are not the final residents of a mature starter, and then activity drops while the acid level climbs. Smells can range from sharp or cheesy to something like nail polish remover or even old gym socks. This does not mean the starter has failed. Keep feeding on a steady schedule, usually once a day at first, and the smell tends to settle into something tangy and pleasantly yeasty. ## Days five to ten: building a reliable rise As the acidity rises, the yeast and lactic acid bacteria that make a sourdough starter work begin to dominate. You should see more consistent bubbles, a looser and more elastic texture, and a visible rise after each feeding. Many bakers move to feeding twice a day once the starter starts doubling reliably, because a hungry, active starter uses up its food quickly. A rubber band or a piece of tape around the jar at the level of the starter after feeding makes the rise easy to track. Over several days, look for the starter to climb noticeably within about four to twelve hours, depending on temperature and feeding ratio, and then fall back slightly as it runs out of food. The timing varies a lot between kitchens, so treat these numbers as rough guides rather than rules. ## How to know your starter is ready to bake with A starter is usually ready when it rises to roughly double its starting volume within a predictable window after feeding, shows plenty of bubbles throughout rather than just at the top, and smells pleasantly sour or fruity rather than harsh. This pattern should repeat for several days in a row. A single good day is not enough, because starters can have strong and weak days while they are still maturing. Some bakers use a float test, dropping a spoonful into water to see whether it floats. It can be a useful hint, but it is not foolproof, since a starter that has already collapsed or been stirred heavily may sink even when it is healthy. The rise pattern is generally a more reliable signal. If your starter is slow after two weeks, try a warmer spot, a little whole grain flour in the feedings, or a slightly lower flour to water ratio and give it a few more days. ## Troubleshooting common problems Liquid on top of the starter, often gray or brownish and called hooch, simply means the starter is hungry. You can stir it back in for a sourer flavor or pour it off before feeding. A dry skin on the surface means the cover was too loose or the air was dry, so scrape it off and use a lid or a damp-proof cover that still lets gas escape. Mold is different and calls for caution. Fuzzy spots in colors such as pink, orange, green, black or white fuzz, or streaks of pink or orange within the starter, are signs to throw the whole batch away and start again with a washed jar. Do not scoop out the affected spot and carry on. A starter that smells strongly rotten rather than sour is also best discarded. If you are unsure, it is safer to start over, since flour and water are easy to replace. ## Feeding, storing and starting your first loaf Once your starter is active, you can keep it on the counter and feed it daily if you bake often, or store it in the refrigerator and feed it about once a week if you bake occasionally. Take a refrigerated starter out and give it one or two feedings at room temperature before baking so it is lively again. Our sourdough starter care article covers storage and recovery in more detail. If you would rather skip the waiting stage, a dried or live starter from a kit is a fast alternative, and our comparison of sourdough starter kits explains how they differ. Whichever route you take, keep your jar clean, watch your feeding times and keep notes on temperature and rise. A little record-keeping makes it much easier to work out why one week behaved differently from the next. [Compare sourdough starter kits](https://fermentnest.com/best/best-sourdough-starter-kits) ## Related buying guides - https://fermentnest.com/best/best-sourdough-starter-kits - https://fermentnest.com/best/best-kitchen-scales-for-fermenting - https://fermentnest.com/best/best-fermentation-thermometers