How to start a sourdough starter from scratch in 7 days

A clean glass jar (250-500ml), whole-grain flour (rye is fastest, whole wheat works too), filtered or non-chlorinated water, a kitchen scale, and a rubber band to mark the starter's level. Skip the fancy crocks for v1 - a jam jar with the lid resting loose on top is what most experienced bakers actually use. The lid stays loose so CO2 can escape. One note on water: chlorine is added to tap water specifically to kill microorganisms. If your tap water is heavily chlorinated, it will suppress your starter. Use bottled spring water, filtered water, or draw tap water into a pitcher and let it sit uncovered for 12-24h — the chlorine dissipates on its own.

Every feed: throw away most of what's in the jar so you have ~50g left, then add 50g flour and 50g water. Stir thoroughly. That's a 1:1:1 ratio (starter : flour : water by weight). Repeat once a day for the first 3 days, then twice a day from day 4 onwards. The discard for the first three days really does just go to compost; once the starter is alive, you can use the discard for pancakes or crackers.

Day 1: nothing visible, mild flour smell. Day 2: a few small bubbles, possibly a slightly tangy or vinegary smell. Day 3-4: this is where most beginners panic. The bubbles often slow down or stop completely; the smell can turn briefly unpleasant. This is normal — when flour meets water, over 150 different yeast and bacterial species are activated at once. The first big rise on day 3-4 often comes from bacteria that aren't the ones you ultimately want. As you keep feeding and acidity builds, the acid-tolerant wild yeast and lactic acid bacteria win the competition and take over. Day 5-6: real activity returns; the starter doubles in 6-12 hours after a feed. Day 7: it's reliably doubling. You're done.

The famous float test (drop a teaspoon of starter in water; if it floats, it's ready) gives false negatives often enough that I've stopped relying on it. A reliably-doubling starter that doesn't float still bakes great bread. Better signal: take a photo of the jar at feed-time, take another 8 hours later. If the second photo is visibly twice as tall, you're in business.

Sourdough is the kind of project where days blur together and patterns are invisible without a record. Sourdough Tracker keeps each feed, each rise %, each ambient temperature, each photo in one continuous timeline per starter. Two weeks in, the rhythm of your starter (it's different from everyone else's) becomes obvious - and that's when your bakes start landing.