Sourdough starter feeding schedule by temperature

Your sourdough feeding schedule by temperature comes down to one rule: the warmer the kitchen, the more often you feed. At 28C (82F) a starter can peak and start falling in 4-5 hours, so it wants two feeds a day. At 18C (64F) the same starter coasts for 12 hours or more on a single feed. Fermentation roughly doubles in speed for every 8-10C (15-18F) you add, which is why summer and winter feel like two different starters.

Read the temperature, not the clock

A schedule is a starting point, not a law. What you are really tracking is the rise. Feed when the starter has peaked and just begun to sink, the moment it has eaten most of its food and turned acidic. Feed too early and you waste flour. Feed too late and it sours and weakens.

Measure where the jar actually sits. The top of the fridge, a sunny windowsill, and the floor by a draft can differ by 5C (9F) in the same room. A cheap probe thermometer next to the jar tells you more than the wall thermostat does.

A rough schedule by kitchen temperature

These are estimates at a 1:1:1 feed, meaning equal weights of starter, flour, and water, say 30 g each. Judge by the rise, not the hour.

Kitchen temp	Time to peak	Feeds per day
30C (86F)	3-4 hours	2-3
26C (79F)	4-6 hours	2
21C (70F)	6-8 hours	1-2
18C (64F)	10-12 hours	1
4C (39F)	days	weekly

Warm kitchens move fast and turn sour quickly, so smaller, more frequent feeds keep the starter sweet and strong. Cool kitchens stretch every feed out, which is handy when you want a hands-off day.

Change the ratio, not just the timing

If feeding twice a day in a hot kitchen is too much, change the ratio instead. More flour and water per part starter gives the culture more to work through, so it takes longer to peak.

• 1:1:1 peaks fastest. Good for a cool room or a quick rebuild before a bake.
• 1:3:3 buys several extra hours. A solid default for a warm room.
• 1:5:5 can stretch a peak to a full day even on a warm counter.

So a summer kitchen at 28C (82F) fed 1:5:5 behaves a lot like a winter kitchen at 20C (68F) fed 1:1:1. You are using flour to do what cool air would otherwise do. The feeding ratio calculator does the gram math for whatever ratio you pick.

When the seasons shift

The hardest weeks are the changes, spring into summer and fall into winter. A schedule that worked in April can leave you with a hungry, hooch-topped jar by June. When the room warms, expect faster peaks and either feed more often or move to a larger ratio. When it cools, your starter will seem sluggish, but it is just slow, not sick.

If you want to pin a bake to a clock, work backward from the temperature. The fermentation calculator estimates how warmth shifts your timeline so you can plan a feed and a mix around it. For the mechanics of a single feed, see how to feed a starter.

A few signs you are off schedule for your temperature:

• Liquid hooch on top and a sharp smell mean it peaked long ago. Feed sooner or feed bigger.
• A starter that barely rises in 12 hours at room temperature may be cold, underfed, or both.
• A starter that doubles and collapses before you get home wants a larger ratio, not more worry.

Dial the feed to the room and the starter does the rest. All timings here are estimates, so trust the rise in your own jar over any chart.