The Slow Crumb

Starter school · Part 1

Getting a Sourdough Starter Through Its First Month

By Marta Ellis · Updated 11 June 2026 · 6 min read

A new starter is mostly a lesson in patience. The first month follows a predictable arc — early fireworks, a discouraging slump, then slow and steady strength — and knowing the arc in advance saves a lot of unnecessary jar-dumping.

Days 1–5: the false start

A new starter often shows a burst of activity on day three and then goes quiet, which is normal and not a sign of failure. That first rise comes from bacteria that won't survive the culture's falling pH; the yeast you actually want arrives later. Whole rye flour kickstarts fermentation faster than white flour because it carries more wild yeast and nutrients, so many bakers begin on rye and transition to white flour in week two.

Chlorinated tap water rarely kills a starter outright, but filtered water removes one variable while troubleshooting. Room temperature swings change how quickly a starter peaks, so bakers in cold kitchens often park the jar near the oven light.

Suggested feeding log
WhenRatio (starter : flour : water)Notes
Days 1–71 : 1 : 1, once dailyRye or 50/50 rye-white
Days 8–141 : 1 : 1, twice dailyTransition to white flour
Days 15–281 : 2 : 2, twice dailySlower cycle, stronger culture

Weeks 2–3: building rhythm

Discarding half before each feeding keeps acidity in check and stops the jar from overflowing. Switching feeding ratios from 1:1:1 to 1:2:2 slows the cycle down for people who cannot feed twice a day. Hooch, the grey liquid that forms on a neglected starter, can simply be stirred back in or poured off — it's a hunger signal, not a death certificate.

A ripe starter smells pleasantly tangy, somewhere between yoghurt and green apple, rather than sharply of acetone. If you're getting nail-polish smells, feed more often or move the jar somewhere cooler.

About the float test The float test is a rough guide at best, since a well-fermented starter can still sink if it was stirred recently. Trust rise, smell, and bubble structure over a spoonful in water.

Week 4: knowing it's ready

By week four a healthy culture doubles predictably within six hours of feeding at room temperature. Predictability is the whole test — a starter that doubles on schedule three days in a row is ready for bread, whatever the calendar says. From there it's maintenance: regular feeds, an occasional rest in the fridge, and the occasional rye top-up when it seems sluggish.