Managing Sourdough Starter

At times, my home projects absorb my time and attention as much as the ones I do for work. This post is the first of what I hope to be a “Behind the Scenes” series of insights that I have learned from these hobbies.

In mid 2020, I decided to take up sourdough bread making. As with many projects, it took me a while to master making this type of bread. Most of the complexity came from my “newcomer” status with sourdough starter. Dozens of loaves later, I now feel like my starter and I have come to an understanding. Here I share what I learned.

What is this starter thing?

Generally speaking, sourdough starter is simply flour and water that also has absorbed and incorporated the yeast that is naturally in the air. While it takes a bit to get started, once done, it is straight-forward to keep going. An active sourdough starter can be used in place of yeast in a recipe (with some adjustments to the recipe to account that the starter is also flour and water). However, the way that this yeast was cultivated gives the things created with it a unique flavor and texture. This guide won’t talk about creating a new starter or how to substitute it for yeast in recipes. But, it should give you a firm starting point to start making things with it, setting the stage for your own experimentation.

How to feed your starter

If you’ve ever read a recipe that has sourdough starter as one of its ingredients, it is nearly a given that it indicates if the starter should be fed or unfed (also called “discard”) when used. These terms refer to how recently you have added fresh flour and water to the starter to “feed” it.

add equal parts by weight of flour and water

Most instructions will lead you to believe that there is a lot of precision required when feeding your starter. I have generally found this to be misleading. The only thing that is important to be somewhat precise about when feeding your starter is that you should add equal parts by weight of flour and water. (Yes, you’ll need to invest in a kitchen scale if you don’t already have one.) All other feeding suggestions can change the behavior of your starter a bit, but generally will not have a significant effect on the things that you make with your starter.

The steps for feeding your starter are:

  1. Let your starter get to room temperature (if needed)
  2. Remove some of the starter (usually, but not always)
  3. Add equal amounts by weight of flour and water and mix well
  4. Allow it to get to maximum “fed” state
  5. Store in the refrigerator (if you don’t plan to use it for a week or more.)


Yeasted things are most active when warm and least when cold. Sourdough starter is no exception. If you need the process to speed up, put your starter in a warmer place - want more time, put it in a cooler place. To qualify “warm” and “cool”, we’re talking about the range between the temperature in your refrigerator to the temperature in a warm room. Any cooler or warmer will probably make all of those living organisms pretty unhappy. Most recipes assume that you are working at “room temperature” when they describe timings.

If you have been storing your starter in the refrigerator, you will want to let it warm up to room temperature before feeding it (again, not strictly necessary, but helps with other steps going faster.) It can take several hours for it to warm up (and starter can sit at room temperature for a day or two with no ill effect), so it is a good idea if you take it out of the refrigerator early in the morning, or even the evening before you are going to use it.


At its core, you discard sourdough starter only so that you don’t end up with an unmanageable amount. You have to feed the starter to keep it alive, and doing so makes more starter equivalent to the total weight of flour and water that you have added. So, to keep your starter at a consistent amount before and after feeding, you should plan first to discard approximately the equivalent amount that you’ll be adding. But, if you are going to need more starter for your recipe, you may not want to discard any before feeding. In addition, it is a good idea to not go below equal parts (by weight) of existing starter, flour and water when feeding; equal parts of each of the three usually leads to a very frothy and happy fed starter.

stir your starter before discarding or using it

Since many recipes call for about 227g of starter, I usually discard about this amount, being sure to leave about 113g of starter in the jar, and then add 113g of flour and 113g of water (more of this in the next section). If a recipe calls for more than this, I simply feed it again once it gets to the maximum “fed” state (step 4). The starter loves to have seconds! :)

Regardless of how many (and whether) you discard any starter, you should always thoroughly mix your starter at this point. If liquid has separated and sits on top, just stir it back in. I stir with a regular spoon with no particular technique.

WHAT TO DO WITH THE DISCARD? There are so many great recipes that are made with sourdough discard; King Arthur Baking ( has a bunch to get you started. But, sometimes you don’t want to make another thing! The sourdough smells pretty bad in the garbage and attracts critters, and the starter can get quite glutenous leading to plumbing clogs. You can spread the starter on a baking tray and bake it until it is dried out and just throw it away. I usually put my baking try of discard into the oven after I’ve turned off the oven from baking a loaf of bread. I leave it in there as the oven is cooling off, which is just about perfect timing for drying it out.


While it is important to add equal amounts of flour and water to the existing starter, the other variables that are flexible. I most commonly add 113g unbleached all-purpose flour and 113g of room temperature water to 113-200g existing starter (don’t forget to account for the weight of the jar!)

I have a couple of common modifications that may come in handy:

  • I need more than 227g of starter for my recipe: Discard less starter or feed the starter more than once
  • Starter is “weak” and doesn’t seem to be expanding as robustly after feeding: Use whole wheat flour instead of some or all of the all purpose flour
  • I don’t have much time and need maximum fed starter quickly: Use warmer water
  • I ran out of unbleached all-purpose flour: Use whatever flour I have, or feed it another day


First, I should mention that this is a term that I think I made up, so don’t be surprised if no one knows what you’re talking about if you say these words!

Once you add the flour and water to your existing starter, you need to wait for your starter to have its meal before it can contribute to yours. As the starter consumes the newly-added flour and water, it expands; you want to wait until it approximately doubles in size before you use it. The best way to gauge how much the starter has grown is to mark your jar at the level of the mixture just after adding the flour and water. Since the starter jar is clear, you will be able to see how much it has grown. I usually use a rubber band to mark these levels. While it isn’t strictly necessary, I usually lightly cover the starter during this period, just to make sure that nothing gets into the jar that shouldn’t.

How long does it take for the starter to expand? That depends on the temperature of the room, the temperature of the water that was added, and the type of flour. The humidity may also play a factor. I usually try to give my schedule plenty of time for this stage in case the starter doesn’t expand as quickly as expected. My favorite bread recipe has the dough sitting in the refrigerator overnight, so I usually feed my starter and make the dough the day before.

If you do not plan to use your fed starter, you can wait just a short time for the process to get going before putting the starter into the refrigerator (if this is where you store it). There is no need to wait until the starter gets to its maximum fed state before doing so.


If you won’t be using your sourdough starter for several days, it is a good idea to put it into the refrigerator where the starter will take longer to get hungry again. This action will give you a week or more before you’ll need to feed the starter again. I usually feed my starter once a week, usually taking the opportunity to make a Saturday morning popover or a Sunday loaf.

How to store your starter

Starter doesn’t mind a messy jar. Unless you see visible mold on the starter jar, you will not need to move the starter to a different home or clean the jar. Often some starter will dry out, particularly near the top of the jar if you pour the starter into your bowls when using it. This dried starter is still alive, and if it flakes off back into the jar, it will reconstitute itself and be usable again.

It is not necessary for the starter to be in an airtight container. In fact, it doesn’t really need to be covered at all, but since this can lead to potential accidents, it is handy for your jar to have at least a loose-fitting lid. When the starter is being fed, it is probably better for it not to be in an airtight container because it can produce unnecessary pressure in the jar from the expansion.