Many sourdough techniques suggest throwing away half your starter further on in the fermenting process. The reason given (in many YouTube videos I've watched) is that it'd eventually take over your kitchen if you didn't.

I guess rather than throw this away I can give it to a friend (or friends) to bootstrap their own starters?

  • Both answers are correct - but have a different perspective. One talks about mature starter, the other about a starter in the first (not-yet-stable) stages.
    – Stephie
    Commented Jun 13, 2019 at 11:48
  • @Stephie given the question, I assume this is a question about an established starter. I don't see how either answer refers to a "not-yet-stable" starter.
    – moscafj
    Commented Jun 13, 2019 at 15:31
  • 2
    I really have to ask: Once you've removed one half of the starter from the other half, what do you think is the difference between those two halves?
    – Sneftel
    Commented Jun 13, 2019 at 17:20
  • @Sneftel - that's why I asked the question. Also of interest, and I hadn't thought about it when I asked the question, was this ok to do with an established starter.
    – Kev
    Commented Jun 13, 2019 at 18:34
  • It's not a bootstrap. It's giving them a starter. Commented Jun 14, 2019 at 1:10

2 Answers 2


Absolutely you can. When you use the starter to make bread you make an arbitrary decision of which part of the starter you use and which to feed, the part you scoop out is just as viable as the part you keep. When you discard some instead of using it the same rule applies, so all you need to do is put some in a container and feed it the same way. You can split the starter as many times as you like, that's the beauty of it.


Sure, you can begin a new sour dough starter with the discard from a feeding. However, the reason for discarding isn't simply to reduce the amount. As your starter matures it also becomes much more acidic. Acidity is problematic for yeast and bacterial activity and, ultimately, the rise and flavor of your final product. So, you discard during feeding time to keep the acidity in check, and ensure that your starter is as hospitable to yeast and bacteria as possible. Your friend can get his or her starter going with your discard, but will then want to get into the habit of discarding when they feed.

  • 5
    TL:DR: dilution of the starter is the necessary thing. The discarding is just because you only want to keep a near-constant amount, not an exponentially-growing amount, and normally you don't have anything better to do with the other part. Commented Jun 13, 2019 at 14:28
  • @PeterCordes my point is that the purpose of discarding is not simply about keeping a consistent amount.
    – moscafj
    Commented Jun 13, 2019 at 15:28
  • 3
    @moscafj, This depends on how you measure your feeding. If you do it by weight ratios, discarding is simply about keeping a consistent amount. For instance, I feed my starter by mixing 1 part starter, 4 parts flour, 4 parts water by weight. If I never discarded, I would never have a problem with excess acidity--but I would rapidly have more starter than I could possibly handle. If you go by a more traditional method along the lines of "discard 1 cup starter, add half cup flour and half cup water" then you'd be right--because if you didn't discard, the ratios would change.
    – rsandler
    Commented Jun 13, 2019 at 16:44
  • @rsandler clearly...I think it is safe to assume most people use the more traditional approach, and also don't want excessive amounts of starter on hand.
    – moscafj
    Commented Jun 13, 2019 at 16:58
  • @rsandler: Can you please explain (or maybe rephrase) your method of "1 part starter, 4 parts flour, 4 parts water by weight"? I always thought a "part" in a recipe referred to volume not weight. Thanks.
    – Arlo
    Commented Jun 18, 2019 at 21:42

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