Updated October 2026
How to Make a Sourdough Starter From Scratch
A week of daily feeds at 70 to 80°F. Don't taste it raw, and discard it if it molds.
Mix 50 g of whole wheat or rye flour with 50 g of water, cover loosely, and keep it at 70 to 80°F. Each day, discard all but 50 g and feed it 50 g flour and 50 g water. It is ready when it doubles within 4 to 8 hours of a feed. Colorado State University Extension reminds bakers that flour is a raw agricultural product: do not taste raw starter, and let baking make it safe.
Day by day
| Day | What to do | What you should see |
|---|---|---|
| Day 1 | Combine 50 g whole wheat or rye flour and 50 g water; cover loosely at 70 to 80°F. | No activity. |
| Day 2 | Stir only. | Early bubbles that may fade. |
| Days 3 to 7 | Discard to 50 g, feed 50 g flour plus 50 g water, once a day. | Rising after feeds, tangy aroma. |
| Day 7 and after | Daily feeds until it is consistent. | Doubles in 4 to 8 hours. |
Feeding helper
Work out your feed
Each card shows how much flour and water to add to the starter you keep, and the total weight you will end up with. Cups are approximate. Discard or use any extra starter before you feed.
Safety basics
- Raw flour: the FDA has linked outbreaks of E. coli and Salmonella to flour. Never eat raw flour, dough, batter or starter, and wash your hands and counters after handling it.
- Mold: any fuzzy or colored growth means discard the starter and clean the container thoroughly.
- Hooch: the alcohol-smelling liquid is harmless; pour it off or stir it in.
- Friendship bread starters with milk: use pasteurized or cultured dairy and keep them in the refrigerator, per Colorado State University Extension.
Temperature and elevation
Colorado State suggests a comfortable room temperature, around 70°F; Illinois Extension gives 70 to 82°F. Cold kitchens slow the starter down, and very hot ones can make it collapse. At high elevation, use recipes adjusted for altitude, since lower air pressure and humidity change how dough rises.
Maintenance
Feed it daily on the counter if you bake often, or weekly in the refrigerator if you bake now and then. Cook the discard in pancakes, waffles or crackers.
Sources we checked (October 2026): Colorado State University Extension, Sourdough Starter Best Practices; University of Illinois Extension, Sourdough Bread 101; US Food and Drug Administration, Handling Flour Safely.
Common questions
How long does it take to make a sourdough starter?
About a week of daily feeds at 70 to 80°F. It is ready when it doubles within 4 to 8 hours of feeding.
Is it safe to taste sourdough starter?
No. Flour is raw and can carry E. coli or Salmonella. Bake it first.
What should I do if my starter grows mold?
Discard it, clean the container thoroughly, and start again.