How to Feed a Sourdough Starter (and How Often)

A starter is a living thing, a little community of wild yeast and bacteria that's been eating flour and water since the day you made it. Feeding it is just giving it more of the same before it runs out of food. That's the whole concept. Everything past that is ratios and timing, and those are the parts people get stuck on, so let's get into it.

My exact routine

Here's what I actually do, every single time. I weigh 30 grams of starter into a clean jar, then add 100 grams of water and 100 grams of flour, which for me is 70 grams bread flour and 30 grams rye. Stir until there's no dry flour left and it looks like thick, lumpy batter. Then I put a rubber band around the jar at the current level, so I can watch what it does, and set the lid on loose. Never sealed. A sealed jar of active starter is a pressure experiment you did not sign up for.

Then I leave it alone for 6 to 8 hours. That's it. No hovering, no stirring it again, no checking every twenty minutes. Go live your life and come back.

The loose lid isn't a suggestion, either. A jar of active starter with a sealed lid builds up gas with nowhere to go, and it will find somewhere to go on its own schedule, usually a messier one than yours. A coffee filter and a rubber band, or just the lid set on top without tightening, is all it needs. It's still eating and breathing in there.

That 70/30 bread-to-rye split isn't sacred, it's just what works for mine. A chef friend talked me into it years ago after I was running two separate starters like an absolute maniac, and it gave my starter more strength to rise and fall on a predictable schedule. If yours is younger or sluggish, leaning more toward rye for a few feedings tends to wake it up.

How often: counter vs. fridge

This is the part that actually depends on your life, not a rulebook.

If you're baking a lot, or your starter is new and still proving itself, keep it on the counter and feed it around the same time every day. It likes a rhythm. That was my whole setup when I first started, and I do think the loaves were slightly better for it.

Mine lives in the fridge most of the week now, because that's what my actual schedule allows. I pull it out about once a week, feed it, bake with it, and put it back. The fridge slows everything down, which buys you time you don't get on the counter, and I've found it matters less what time of day I feed it than whether I wait until it's actually hit its peak and started to fall before I feed again.

The one rule I hold myself to is not leaving it unfed for more than 2 weeks. Past that it starts to harden on top, and if you really let it go, mold shows up after about a month. Hardening isn't the emergency. Mold is the only time you're actually starting over.

Discard, and why it exists

Every time you feed, you're also getting rid of most of what was already in the jar, down to that 30 grams I mentioned. That leftover portion is discard, and the name makes it sound like trash when it isn't.

Discarding exists so your starter doesn't outgrow its jar and turn sluggish trying to feed a population that's gotten too big for the amount of fresh flour and water coming in. Keeping the ratio in check is the whole point. I keep mine in a separate jar in the fridge and use it up within the week.

What you do with the part you remove is its own topic. Short version: don't throw it away.

Three signs it's fed and happy

After a feeding, here's what I'm actually looking for:

• Bubbles. Little ones scattered through it, a sign the fermentation is active.
• Rise and fall. It should puff up after feeding and then settle back down. That cycle, repeating, is the whole sign of a healthy starter.
• A tangy smell. Yeasty, a little sour, like fresh sourdough bread before it's bread yet.

Get those three and you're in good shape. You don't need a perfect double every time or a science-fair chart. You need a starter that's doing its job.

What to do if you forgot

You will forget. Everyone does, and it's rarely as bad as it feels in the moment.

If there's no mold, here's the fix. Discard down to about 30 grams, feed it 1:1 flour and water, and repeat that every 12 hours for a few days until it's doubling in size again and smelling tangy instead of flat. That's the same reviving move whether it's been a week or closer to a month of neglect, and it works more often than people expect.

If you're standing over the jar trying to decide whether what you're looking at is a problem or just a hungry starter doing its thing, I wrote a whole guide for exactly that moment: is my sourdough starter dead?

Bake it anyway

I've killed more than one starter to neglect, a move, or just a busy season, and every time the fix was the same: feed it, wait, and trust that a slightly sad-looking jar on your counter is still doing its job. You don't need a perfect routine, you need a routine you'll actually keep up with. Feed it, watch it, and bake it anyway.