Give the maintenance jar and the bake jar separate jobs
The mother jar is the culture you keep from one bake to the next. The build is a portion of that culture fed to reach a particular weight and ripeness for one recipe. Keeping those jobs separate lets you make a large build without feeding a large jar every week. King Arthur and The Perfect Loaf both describe smaller maintenance routines for established starters. Follow a dedicated creation method if your culture is still getting established. [1] [2]
Start with quantities your scale can read reliably. In the example below, the mother jar uses 10 g of starter, 20 g of flour and 20 g of water. That is 50 g after feeding at 1:2:2. This is a worked quantity example. Choose a maintenance ratio and feeding interval that suit your own jar.
| Job | Starter to keep or take | Flour | Water | Total |
|---|---|---|---|---|
| Routine mother feed at 1:2:2 | 10 g | 20 g | 20 g | 50 g |
| Build for a 150 g recipe portion | 34 g | 68 g | 68 g | 170 g |
| Build for a 60 g recipe portion | 16 g | 32 g | 32 g | 80 g |
The build rows are alternatives. Each starts from a refreshed 50 g mother jar and leaves enough seed behind for another routine feed. A few grams can stick to a jar or spatula, so treat those totals as the amount mixed.
Work backwards from what the dough needs
For a recipe that needs 150 g, add a 20 g margin for jar losses or a little spare. At 1:2:2, divide the 170 g target by five total parts. One part is 34 g. Take 34 g from the active mother, add 68 g flour and 68 g water, and leave the build to ripen. From the approximately 16 g remaining in the mother jar, you can keep 10 g for its next feed.
For a small loaf needing 60 g, an 80 g build at the same ratio uses 16 g starter and 32 g each of flour and water. A build does not have to match the mother jar’s flour blend. If the recipe specifies a particular blend or hydration, use its build instructions and calculate the reserve separately. [2] [3]
Keep a small amount your scale can actually weigh
A display that rounds to whole grams has a larger effect on a 2 g scoop than on a 20 g scoop. Even a one-gram difference is half of a 2 g target. If the display jumps, fails to register a small addition or changes when you lift and replace the jar, use a larger batch with the same proportions. Doubling every number in a feed keeps the ratio unchanged.
Write down the three weights you actually used and the time of the feed. That lets you compare the rise with a similar feed next week. If you often bake twice a week, list both recipe quantities before you decide how large the mother jar needs to be. You can make two builds from the same jar if you still have enough seed for its next feed. A smaller batch still needs to be ready when you use it. Plan enough time for the build to meet the recipe’s cues.
Count discard over a normal week
Imagine you feed once in a non-baking week. Starting with 50 g of mother starter, keeping 10 g leaves 40 g to remove before the feed. With a larger 150 g routine where you keep 30 g, the equivalent amount is 120 g. Both examples use 1:2:2. The smaller routine produces 80 g less excess at that feed. Your weekly figure changes if you feed more often or use part of the jar for a bake. Use healthy established discard only in a suitable cooked recipe. [1] [4]
Crispy Crust’s planned starter tools are designed to separate the maintenance feed from the recipe build. You could work out the grams for the loaf and keep a visible reserve for the mother jar before deciding how much to take.
Use the starter feeding calculator to calculate the build you need while keeping a reserve.