Feeding without discarding means the jar doubles every time. Start with 100 g, feed 1:1:1 twice a day, and inside a week you have kilos.
But volume isn't the real reason. The reason is ratio. A culture needs enough food per microbe to keep growing vigorously. If you keep everything and add a modest feed, the population is enormous relative to the food, it burns through it in an hour, and then sits in its own acid and waste for the rest of the interval. That's how you get a permanently sour, sluggish starter.
Discarding isn't throwing away a resource. It's how you keep the food-to-microbe ratio somewhere the culture can thrive.
Most discard problems are a maintenance-volume problem wearing a costume. People keep 200–300 g of starter because that's what the jar holds, then generate 200–300 g of discard per feed and feel obliged to bake their way out of it.
Work backwards from what you need instead. The Calibration Loaf takes 100 g. So:
| Situation | Keep | Discard per feed |
|---|---|---|
| Not baking this week | 10–20 g | ~10 g |
| Baking one loaf | 20 g, then build to 100 g | ~10 g |
| Baking two loaves | 20 g, build to 200 g | ~10 g |
Ten grams a feed is a teaspoon. At that scale discard stops being a moral event and becomes a rounding error — no recipes required, no jar accumulating in the fridge.
Discard is unfed starter: flour, water, and a hungry culture that has already spent its rise. It will add a pleasant tang and some tenderising acidity. It will not leaven anything. Any discard recipe that rises does so with baking powder or soda, and that's correct — not a workaround.
It keeps in a covered jar in the fridge for one to two weeks, getting steadily more sour. Add to it as you go. Discard it for real if it grows anything coloured or fuzzy, which is the same rule as everywhere else.
Best uses are things where tang is welcome and structure comes from elsewhere: pancakes and waffles, crackers, flatbreads, banana bread, pizza dough where commercial yeast does the lifting. Worst use is anything that needs to rise on the discard alone.
Notes from the counter
There's a real guilt economy around discard, and I think it's mostly imported from somewhere else. Ten grams of flour and ten grams of water is, at supermarket prices, well under a cent. You are not wasting food in any meaningful sense — you're at roughly the scale of the flour left in the bag.
What the guilt actually produces is worse: people keeping oversized starters to avoid discarding, which makes the starter worse, then baking discard recipes they didn't want to solve a problem they created.
Keep twenty grams. Discard a teaspoon. Make the pancakes because you want pancakes.