![Grow a sourdough starter from scratch in 7 days](https://cdn.slatesource.com/7/a/9/7a936566-220a-4a7f-9c16-3fa7c1e3886e.webp) # Grow a sourdough starter from scratch in 7 days - [Made in Slatesource](https://slatesource.com/@steph/grow-a-sourdough-starter-from-scratch-in-7-days) - By [Steph](https://slatesource.com/@steph) - Created on Oct 9, 2026 ## Two ingredients, seven days, bread for life A sourdough starter is nothing more than flour and water left in a warm jar. Wild yeast and lactic acid bacteria from the flour and the air colonise it, feed on the sugars, and produce the carbon dioxide that makes bread rise. Once active, a starter kept in the fridge needs only a weekly feed to stay alive indefinitely. Many bakers use starters decades old. This tutorial takes you from day one to a proven, active starter in seven days, with exact gram weights at every stage, a troubleshooting table for every common problem, and a clear maintenance schedule for afterwards. ![](https://cdn.slatesource.com/7/a/9/7a936566-220a-4a7f-9c16-3fa7c1e3886e.webp) Nutrition, Food Safety and Health (CC0). Feeding a sourdough starter. Total time 7 days, 5 minutes active per day Difficulty Beginner, no baking experience needed You will need A glass jar (at least 1 litre), scales, flour, water Flour for days 1 to 4 Whole wheat or rye (not all-purpose yet) Water Filtered or bottled. Tap chloramine slows fermentation. Ideal kitchen temp 22 to 26 C (72 to 78 F) ## Why whole wheat flour for the first days The outer bran of whole wheat and rye flour carries far more wild yeast and bacteria than white flour does. Starting with whole grain flour gives the culture a faster and more reliable launch. Once the starter is active and stable, around day 5 or 6, you can switch to unbleached all-purpose flour for maintenance feeding without losing any strength. If you only have all-purpose flour, use it throughout. It will work; it may just take an extra day or two to show consistent activity. ## Day 1: mix the first culture Weigh 50 g of whole wheat or rye flour into a clean glass jar. Add 50 g of filtered water at roughly 30 C (86 F), warm but not hot. Stir well until no dry flour remains. The texture should be like thick peanut butter. Cover the jar loosely with a cloth held by a rubber band, or rest the lid on top without sealing. You want airflow in, not an airtight seal. Leave it somewhere consistently warm for 24 hours. The top of a fridge or near (not on) a warm appliance works well in most kitchens. ## Day 2: look, stir, and wait Open the jar and look for any sign of life: a bubble or two near the wall, a slight puff, any change in texture. Many starters show nothing at all on day 2, and that is completely normal. Stir once to oxygenate the culture, re-cover, and leave for another 24 hours. Do not feed yet. ## Day 3: first discard and feed By day 3 you begin the daily rhythm: discard, then feed. Discard: pour away enough starter to leave exactly 25 g in the jar. A kitchen scale makes this precise. Discard the rest (or save it for pancakes or waffles, where an active starter is not required and the flavour is a bonus). Feed: add 50 g of whole wheat flour and 50 g of filtered water at 30 C. Stir until smooth. Cover loosely and leave for 24 hours. This is a 1:2:2 feeding ratio (1 part starter to 2 parts flour to 2 parts water). The discard step removes acids that would otherwise slow the culture. ## Days 4 to 6: increase the feed Continue the same daily routine but increase the flour and water slightly. Each day: keep 25 g of starter, discard the rest, then add 75 g of flour and 75 g of water at 30 C. Stir, cover, wait. This is a 1:3:3 ratio and gives the microbes slightly more food, accelerating the culture. From day 5, switch to unbleached all-purpose flour if you prefer. Whole wheat continues to work fine. Watch for: the starter doubling in volume within 4 to 8 hours of feeding, visible bubbles throughout the jar (not just at the surface), a smell that shifts from sour or unpleasant to yeasty, slightly tangy, almost beer-like. ![](https://cdn.slatesource.com/d/b/5/db59188d-ca66-40c8-93d3-ba38b6c98f46.webp) Nutrition, Food Safety and Health (CC0). Starter beginning to bubble on day 4. ## Day 7: the readiness tests A starter is ready to use when it doubles reliably within 4 to 6 hours of feeding, has bubbles throughout, and smells yeasty and mildly sour. The float test confirms it. Drop a small spoonful into a glass of water. If it floats, it has trapped enough gas to leaven bread. If it sinks, give it one more feed and retest in 4 to 6 hours. Do not rush this. Some starters are active on day 5; some need day 10. Cold kitchens and hard tap water are the two most common reasons for a slow start. Ready sign 1 Doubles in volume within 4 to 6 hours of feeding Ready sign 2 Bubbles visible throughout the jar, not just on top Ready sign 3 Smells yeasty and lightly sour, not putrid or sharp Float test A spoonful dropped in water floats when starter is ready ## Troubleshooting every common problem Hooch: a grey or clear liquid pooling on top is simply the starter hungry between feeds. Pour it off or stir it back in, then feed. No bubbles after 5 days: check the kitchen temperature (below 20 C suppresses activity sharply), switch to filtered water if you have been using tap, and try mixing in a spoonful of rye flour for a boost. False start: activity sometimes surges on day 2 or 3, then stops. This is leuconostoc bacteria causing early froth before the real yeast culture takes hold. Keep feeding. It will restart. Pink or orange streaks: contamination. Discard the starter completely, wash the jar with boiling water, and begin again. Smells like nail polish remover: too much acetone from ethanol fermentation. Feed more frequently, twice a day, for two days. Liquid on top (hooch) Normal. Pour off or stir in, then feed. No bubbles by day 5 Too cold (below 20 C) or chloramine in water. False start day 2 or 3 Leuconostoc bacteria. Keep feeding. Pink or orange colour Contamination. Discard and restart. Nail polish remover smell Feed twice a day for two days. ## Keeping it alive: the fridge routine Once your starter is active, baking every week is not required. Feed the starter until it shows bubbles, then seal the jar and refrigerate. At 4 C the culture slows almost completely and will stay alive for 7 to 10 days with no attention. To bake: remove the starter from the fridge 8 to 12 hours before you need it. Give it one feed (keep 25 g, add 75 g flour and 75 g water). When it has doubled and passes the float test, it is ready. If it has been in the fridge more than two weeks, feed it two or three times before baking. To maintain with no baking: discard half and feed once a week, let it bubble for an hour, then return it to the fridge. The discard from each feeding is not waste. Before your starter is fully active use it in pancakes, waffles, crackers or flatbreads where a long slow proof is not needed. Active discard works in quick breads and muffins. Bakers develop a second jar just for discard. [Baker Bettie: complete beginner sourdough starter guide with daily gram weights](https://bakerbettie.com/how-to-make-a-sourdough-starter/?utm_source=slatesource) [SourdoughStarter.com: troubleshooting guide including hooch, contamination and temperature](https://sourdoughstarter.com/blogs/bakers-playbook/sourdough-starter?utm_source=slatesource)