You’ve rehabilitated your dried sourdough or grown one from scratch. You now have what feels like a precarious and tender child on your hands. You can do one of two things: bake bread now, or put your sourdough to sleep, destined for later use.
Starter maintenance requires two jars: 1 for discard and 1 for your active ‘mother’ starter (we will call these the discard jar and the active jar). Keep the discard jar in the fridge. As you maintain your starter, put any excess from feeding sessions into it. The discard will last for a couple weeks in there, continuing to sour (slowly) as it sits. Use in flatbreads, pancakes, cookies, cakes, etc. or anything that doesn’t require a lot of leavening. (The refrigerator doesn’t stop fermentation entirely, but it retards activity considerably.)
Your active jar is your main squeeze. If you’re baking daily, keep it on the counter with consistent feedings every time it peaks (doubles and begins to recede). If you’re mostly keeping it in the fridge and only refreshing for intermittent bakes, take it from the fridge and feed once every week or two. Return to the fridge once fed. This keeps the starter happy and healthy and in need of only a couple refreshments before use. If you’ve kept it dormant in the fridge and want to bake, remove with enough time to give it at least two feedings before building a specific portion for your dough (this portion is called the levain). This usually means removing from the fridge and feeding 24-36 hours before you plan to bake. The more consistently and considerately your starter is fed, the better it will perform. Like you, like me.
An example of a feeding schedule is as follows:
Let’s say it's Monday, another 8am. I wake and take my active jar from the fridge. There sits 100g of sourdough, probably at least a few days retired. I remove 15g and put it in a clean little bowl. I put the remaining 85g into my discard jar and pop it back in the fridge. I give the active jar a rinse and a quick dry. I feed the 15g in the bowl with 30g of flour and 30g of water and mix with my clean fingers. I scoop this mixture back into my active jar, put a rubber band around it to mark the level, cover it with a loose lid and walk away.
Monday, 2pm, I check the active jar. There are signs of life, but not necessarily robust activity. It has grown past the rubber band line, about doubled but not quite. I remove 20g and put it back into that little bowl, and scoop the remaining 55g into my discard jar. I feed the 20g with 40g flour and 40g water, mix with fingers, place back into the active jar and mark the side. Cover and walk away.
Monday, 10pm, phew. How is my starter? Alive. It’s grown well over the line. I’d like to bake in the morning, so I plan for a build that will let the starter feast all night. The higher the proportion of food to beasts, the longer they will go without depleting the supply. Let’s say my recipe calls for 150g of starter. I’d like to make that much and then some, so that I have some leftover to maintain my culture (alternatively, I could make just the right amount and refresh later from my discard jar, which also serves as a backup stockpile, so long as it doesn’t all go to the pancakes). I remove 20 of the 100g of starter in my active jar and put the rest in discard jar. I feed this with 80g flour and 80g cool-ish water, and mix with my fingers. I put it into my active jar (maybe replacing it with a slightly bigger vessel for the increased volume of this build), mark and cover it and leave it be until morning.
Tuesday, 8am, just 24 hours since I roused my sleeping starter. It is doubled and ready for use. So I use it. I’m left with 30g in my active jar, so I feed it with 30g flour and 30g water. If I want to bake again the next day, I leave this on the counter and maintain a low volume feeding schedule, gradually building the measurements up to the necessary amount for a recipe over the course of a few feeds. Otherwise, I put it to rest in the fridge again until the next bake.