how to feed sourdough starter

6 tips for feeding and discarding your sourdough starter

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If you’re a casual sourdough baker looking to keep your starter alive and healthy while making the feeding and discarding process as simple and straightforward as possible, read on.

First, I have a confession to make: I killed my first sourdough starter. It arrived in a tiny jar from King Arthur Flour’s HQ in Vermont where they’ve been maintaining the same mother starter for over 100 years. I carefully grew it from 1 oz to a healthy 12-ish oz starter which I kept in a ceramic crock in my fridge.

I don’t bake with sourdough that often (#unpopularopinion: 90% of the time I just don’t think it’s worth the hassle and also I’m very impatient), so I’d take it out every few weeks and feed it according to the instructions — “discarding” half of the starter, adding 1/2 cup water and 1/2 cup flour to what remained, and mixing it all together before putting it back in the fridge to feed.

If I was going to use it, I’d feed it a few days in a row to get it nice and bubbly, but otherwise, I left it alone in the fridge. Then, one day, when I went to feed it I noticed red dots had spread like an angry rash across its surface and up the walls of the crock. I called King Arthur Flour’s baker’s hotline, described my symptoms, and got a diagnosis: MOLD. My starter was dead. RIP!

My current sourdough starter, on the other hand, has been thriving for three years now. It’s survived nearly drying out and two cross-country flights. It lives in a ceramic crock in my fridge, and I feed it every couple weeks or a few days in a row if I plan to baking with it. I am not good at sticking to schedules, so I just try to remember to do it every few weeks and so far that’s worked just fine for me.

A birds-eye view down into the center of a beige, ceramic croc with a dark beige, sourdough starter in it.
This is the starter about halfway through feeding. Eventually it will reach the 8 oz/1 cup line.

If you don’t refrigerate your starter then you’re probably baking with it once or twice a week, you might feed it once or twice a day, and you probably feed it directly in the container. I am not about that life and I cannot tell you how to live that life. I barely remember to feed my cats some days, and even then at least they remind me. So the advice in this post is probably not helpful for you.

If you’re a casual sourdough baker looking to keep your starter alive and healthy while making the feeding and discarding process as simple and straightforward as possible, read on.

how to feed and discard your sourdough starter

When I killed my first starter, I was so confused. What had gone wrong? I had followed the instructions exactly, scooping out and “discarding” approximately half the sourdough starter at every feeding. Yes, it was hard to tell what exactly “half” was, and yes, I was adding the 1/2 cup flour and 1/2 cup water right into the crock at feeding time, even though I knew volumetric measurements were wildly imprecise.

But I was following the instructions, so I kept going, even as a little voice in the back of my head whispered: This can’t possibly be right. Reader, I should’ve listened to that voice.

So how do you keep your sourdough starter alive and healthy?

1. Feed your sourdough starter in a clean container, and clean your sourdough crock or container between feedings

It turns out if you don’t clean your sourdough crock like, ever, you’re gonna get mold. In hindsight, yes, duh. But I was following the instructions! They said to discard half the sourdough starter, and I assumed that meant discarding the half I removed from the container, because why would you take out the stuff you’re gonna keep? It just didn’t make sense to me!

Now, I know feed my starter in a clean bowl or container and discard (or use) the starter that’s left in the container. Then, I clean the container I keep my starter in, and transfer the fed starter back to its home to finish feeding.

the beige ceramic crock sits next to a stainless steel metal bowl. both have soudough starter in them.
Fed starter in a clean container (left) and unfed “discard” starter on the right. Both have some bubbles, but the recently fed starter has bigger and more active bubbling.

Think of the unfed (“discard”) starter as an insurance policy. Keep it in its container in the fridge until you see if the newly fed starter in the clean bowl is happy, bubbly, and growing. If it’s not, or if something goes wrong with the feeding, you’ll still have the discard starter as a backup. When the fed starter is happily bubbling, then you can get rid of the discard and clean the container.

IMPORTANT: Make sure the container is clean AND dry AND that there is no soap or soap residue remaining before you put the fed starter back in. Soap can cause mold, and you don’t want mold.

Mold, by the way is usually red and looks like a rash. If you go a week or more between feedings and you open your container and see black/grey liquid collected on top of the starter, that is not mold. It’s a naturally occurring alcohol called “hooch” that is produced by the fermentation process. It’s also sign that your sourdough starter is hungry. Pour as much of the hooch as you can off the top, then stir your starter before feeding it.

A hand tilts a beige ceramic crock forward revealing the unfed sourdough starter.
The black liquid on top of unfed starter is called hooch.

2. Use a kitchen scale to measure by weight to get more control over your starter’s hydration level

Measuring flour volumetrically (cups, tsp, tbsp) is wildly imprecise. Depending on how you scoop your flour into a measuring cup, you might see as much as a 1 oz difference in weight. And that can have a huge effect on the hydration level and health of your sourdough starter. So ditch the measuring cup when you feed your starter, and use a kitchen scale instead.

In baking, the hydration of a dough is calculated using what’s known as baker’s percentage. The amount of flour in a dough is considered 100% and all the other ingredients are calculated as percentages of that amount. So a dough with 1000g flour and 500g water is a 50% hydration dough. The same applies to sourdough starter.

Most sourdough starter has a 100% hydration level, meaning it’s made up of a 1:1 ratio of flour to water. Whether you’re feeding 1 TBSP of starter or 4 ounces of starter, what matters is that you’re adding equal parts flour and water by weight to it at feeding time.

By feeding your starter in a clean bowl using a kitchen scale, you ensure that 1:1 ratio is balanced. Since your starter is already at a 100% hydration, at feeding time, you simply put however much starter you want (I usually do 4 oz when I’m waking it up from the fridge) in a bowl and add 100% flour (4 oz) and 100% water (4 oz) to it. You could also do 50g starter and feed it 100g flour + 100g water — that would also be a 1:1 ratio at feeding time.

If you’re waking your starter up after a few weeks of fridge hibernation, start with a bigger feeding. But if you’re feeding it a few days in a row to get ready to bake with it, you can gradually reduce the amount of flour and water you’re giving it each day, as long as the amount of flour and water remains equal.

Like I said, I usually do 4 oz of each flour*, water, and starter, but if you prefer to maintain a smaller amount of starter you could do 2 oz of each, and if you prefer to maintain a larger amount, or you want to gift some starter to a friend, you could do 5 or 6 oz of each. Just remember, it will grow at feeding time.

A top-down view of a large stainless steel bowl. At the bottom of the bowl is a beige liquid which is a mixture of water and starter. on the surface of the liquid mixture is a pile of flour.

[UPDATE, JULY 2020: I have switched to maintaining a smaller amount of starter and wrote about why and how to do so here.]

The other perk of working by weight is that, say you’ve measured your 4 oz of starter into the bowl, but then accidentally add 4.5 oz water… all you have to do is “tare” the scale back to zero and add another .5 oz of starter. Then add 4.5 oz flour. (Or, you can just add 4.5 oz flour — as long as your flour to water ratio is equal, it’s okay if you have slightly less sourdough starter.) When you’re working with cups or tablespoons, it’s a lot harder to keep that ratio balanced and accurate.

*Sometimes I feed my starter with equal amounts of whole wheat and AP flour. It’s still an equal amount of of flour to water by weight (i.e. 100g water, 50g AP, 50g WW), but I’ve found that the blend of flours produces a stronger starter.

3. Feed your starter using distilled, purified, or filtered water — anything without chlorine

Chlorine will kill your sourdough starter. Full-stop. Some people swear by fancy, expensive waters, but honestly as long as you run your tap water through something like a Brita filter before you add it to your starter, you should be fine.

I feed my starter straight from the water pitcher in my fridge. Because fridge water is colder, it takes the starter a little longer to start bubbling than if I were to use room-temp water. If you use room-temp water, expect to start seeing bubbles within an hour or so of feeding.

4. Mix your water and starter first, then add the flour

Mixing equal parts water, starter, and flour can be tricky — you’re creating a fairly thick mixture, and the flour and starter will quickly absorb the water. You’ll have to stir a lot to break up all the lumps of flour and get the three components incorporated evenly.

A hand stirs the sourdough starter and water with a mini spatula. The starter and water are in a large stainless steel bowl.

Combining the water and starter first helps loosen and dissolve the starter. This makes it easier to incorporate the flour. There’s much less frustrated stirring involved, and your starter will have fewer lumps.

5. Let your starter sit at room temp for 2-4 hours after feeding and before you transfer it back to its (clean) container in the fridge

Sourdough starter and bread dough are similar in a lot of ways. Warmer temperatures make the yeast more active, and cooler temperatures slow them down. Handle a dough too much and you’ll knock the gasses and air bubbles out of it. Same with starter. The stronger your dough is and the stronger the yeast, the more it will be able to bounce back after you knock the air bubbles out. Same with starter.

Letting your starter rest, covered, at room temp (around 70-75 degrees) for a few hours after feeding it gives the natural yeast the perfect environment in which to eat. Your starter will double (or triple) in size and you’ll see lots of bubbles visible on the surface.

If you transfer it into the fridge too soon, the yeast won’t be active enough to produce lots of bubbles. If you leave it out too long, the yeast will eat everything it can and then stop producing more bubbles. You will have over-proofed your starter.

You don’t NEED to keep your starter in the fridge, but if you’re a casual sourdough baker and aren’t using it too often, it helps slow down the activity of the starter. It can go longer between feedings.

Note: Over-proofing or under-proofing your starter in no way harms it or kills it. It just means you’ll likely need to feed it again before you can use it, because you always want it to be active and bubbly when you bake with it.

A ceramic crock filled with bubbly, beige, shiny sourdough starter sits on a marble countertop.

6. Discarding your sourdough starter doesn’t mean you can’t use it! Use your discard starter!

Just because it’s called “discard” doesn’t mean you have to throw it out. And if you do throw it out, please don’t put it down your sink; The gluten can build up and cause clogs, especially if you’re someone who bakes a lot.

So if you’d rather not let your discard starter go to waste, the number one best thing you can do with it… is use it! King Arthur Flour has a whole library of excellent sourdough discard recipes. I love using it to make sourdough beer pretzels and scallion pancakes which are so easy — you literally just pour the discard into a hot skillet and top it with thinly sliced scallions. So easy. So tasty. So not wasteful.

a 2 cup glass measuring cup sits on a silver kitchen scale. the sourdough starter in the cup comes up to the 1 cup line.

Recommended tools

  • Glass jar or ceramic crock with non-airtight lid. If you’re feeding your starter weekly you’re fine with an airtight lid, but yeast creates gas while it’s feeding so if you feed your starter less than once a week, a container with a lid that lets air out is best. If you do go with an airtight lid, you’ll want to “burp” the container every now and then so the gas doesn’t build up inside and cause it to explode. The perk of a glass jar is you can see what’s really going on inside your starter, not just on the surface.
  • Kitchen scale
  • Brita filter (or purified/filtered water)
a 2 cup glass measuring cup sits on a silver kitchen scale. the sourdough starter in the cup comes up to the 1 cup line.

how to feed your sourdough starter

How to feed your sourdough starter to keep it happy, healthy and mold-free. Repeat this process every time you feed your starter, whether you’re feeding it daily, weekly, or monthly. If you’re planning on using it to make bread, feed it a few days in a row to make sure it’s nice and strong. Use the discard to make scallion pancakes.
5 from 1 vote
Prep Time 10 mins
Cook Time 0 mins
Total Time 10 mins
Course Technique
Servings 12 oz starter



  • 4 oz 100% hydration sourdough starter (113 grams)
  • 4 oz filtered water (113 grams) (equal to or more than the amount of starter, AND equal to the amount of flour)
  • 4 oz flour (113 grams) (equal to or more than the amount of starter, AND equal to the amount of flour)


  • Use a kitchen scale to transfer 4 oz (113g) unfed 100% hydration sourdough starter into a bowl.
  • Add 4 oz (113g) filtered or purified water to the starter and mix to combine. The starter will not dissolve entirely, it’s okay if some lumps remain.
  • Add 4 oz (113g) flour to the starter/water mixture and use a bowl scraper or spatula to combine. Try to break up any large clumps of flour, but again, it’s okay if some smaller lumps remain. You shouldn’t see any obvious dry spots.
  • Cover the bowl with saran wrap or a clean dish towel and let sit at room temp until bubbles form. Depending on how cold your water and starter were at the start, it may take anywhere from 1 to 4 hours for this to happen.
  • Meanwhile, clean out the container you usually keep your starter in. Make sure it is dry with no remaining soap residue. Use that discard starter to make scallion pancakes or something. Have fun with it.
    NOTE: If you’re keeping your unfed starter as a backup, wait to do this until you’re sure the fed starter is bubbly.
  • Transfer the newly fed, happily bubbling starter to the clean crock. If not using immediately, refrigerate. If you do plan to use it immediately, leave it out at room temp 6-8 hours (or even overnight) until very, very bubbly.


  • If you haven’t fed your starter for a few weeks, you might see only a few bubbles at first feeding. Feed it two or three days in a row before you plan to use it and you’ll get the happily bubbled starter of your dreams.
  • The 4 oz (113g) measurements in this recipe are just one of many, many ways to feed your starter. You can feed 1 oz of starter with 4 oz flour and 4 oz water. You can feed 1 oz of starter with 1 oz flour and 1 oz water. As long as the amounts of flour and water by weight are equal to or greater than the amount of starter, you’re good!
Love this recipe?Leave a comment and let me know!

Got more sourdough questions? Suggestions for what to do with discard starter? Leave a comment below!

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Question: how long after I feed a starter can I bake with it? After four hours? Overnight? What’s best practice?


If I take a cup from my starter to bake with do I need to feed it at that time


I just want to thank you for clarifying the whole discarding of some of the starter stuff. I was given a starter for Mothers Day and have been watching videos and reading whatever I can to understand the process. No where had I seen/read a reason why you discard some of the starter. The instructions that came with it doesn’t even mention discarding. I kept wondering why, and now I know. I’ll definitely try the scallion pancake too.

Renee Jean

When I give discard to friends do you recommend I feed it first and are they on day one or whatever day I’m currently at if during the 1st week?


Do I always need to feed my starter equal part water and flour? For example if I have 1.5 cup of starter and I want to grow it to give to people or bake with, do I need to feed it 1.5 cups water and 1.5 cups flour?


Hi, I am new to sourdough starter and baking, just to clarify, my starter seems sluggish, not really active, but thick and webby. I feed 1:1:1, 50g starter, ww flour and water, but see no real rise. Should I try less starter and more flour and water? Also, should I use a clean jar each time I discard and feed? Thanks!

Queen Sean

Thank you for your information, just want to know if the starter made from rye or whole wheat can it be used for bake flour bread? it means that can be used for all breads?Thanks

Jami Feezor

Some recipes say to put in refrigerator and take out to make bread which mean a cup taken out is cold and not fed. Other recipes say feed and leave on counter 8 hours and then take out a cup of starter? Use refrigerator starter or overnight starter?


I just began to make my first starter and realized I will be going away for 3 days at day 6. Should I halt and start from scratch when I return or refrigerate at day 6?


Hi there. This is the best explanation of the sourdough process that I’ve come across. Thank you!


Hi! My mother-in-law gave me a start and I misunderstood her and left it on the counter for the last 8 days instead of putting it in the fridge. Will it still be good? She fed it when she gave it to me, but I just don’t know if it’s ok still. Also she uses milk to feed it, should I continue with milk or change to water?

Last edited 5 months ago by Bonnie

Hi I had about 1/2 a tablespoon of starter left in my jar, so I added 1/2 cup of each water and wheat flour then the next day I didn’t discard any and added 1 cup of each then my third day I discard 2/3 and then added 1 cup of each it is so bubbly do you think it is good to use?