Choosing a Sourdough Starter Jar (and answering starter jar questions)

When choosing a sourdough starter jar you want to look for something made of glass that isn’t airtight. There are tons of different options that fit this criteria, so let’s dive into them. Don’t let choosing a starter jar overwhelm you, it’s simple. If you ever want a larger starter or a different jar you can always switch.

Source: Plum Branch Home

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Best Sourdough Starter Jar

As I said above, the best starter jar is a glass jar, preferably clear and made of borosilicate glass. This type of glass is pure, nontoxic, and lead-free. When using this type of jar you won’t have to worry about anything leaching into your starter.

Just make sure the lid isn’t airtight or else it can explode due to the fermentation. If you have a lid that sits on top or one you can loosely tighten, you’ll be just fine.

My Favorite Starter Jar

I have a clamp-lid glass jar that my starter lives in. But I always recommend using a 24 or 32-oz Mason jar and simply not tightening the lid all the way.

Other Sourdough Starter Jar Options

You can also use a stainless steel jar or container but this must be true stainless steel. It’s best practice to look for the 18/8 label.

How do you if a jar is made of borosilicate glass?

Usually, the jar will have some type of label on it at the store that says it’s made from borosilicate glass. I recommend buying your jar online where it’s easy to read the product description.

Mason jars are almost always made of borosilicate glass for the safety of canning food. So if you’re doubtful, just stick to one of those.

Starter Jars Not to Choose

Don’t choose a reactive container or jar, meaning the material it’s made of causes a chemical reaction when the starter fermentation takes place. This reaction can cause your starter to turn colors and kill it.

Steer clear of metals like copper and aluminum. Also if the lid is cloth or cork, ensure it doesn’t touch the starter to avoid the dreaded growth of pink mold that forms from a reaction with the starter.

I also recommend steering clear of anything plastic. Online, many people will tell you to use plastic but I don’t recommend any long-term food storage to be done in a plastic container especially when it’s fermenting.

Use a Rubber Band to Track Sourdough Starter’s Activity

If you’d like to track the progress of your sourdough starter, you can place a rubber band on the outside of the jar. Right before feeding it, place the rubber band where the starter stops. After feeding, in 4-12 hours, you can see how much it’s grown.

2 glass jars
Source: Plum Branch Home

Sourdough Starter Jar FAQ

What is a sourdough starter jar?

It’s a jar where your sourdough starter lives and grows.

What makes a jar good for sourdough starter?

In my opinion, a jar that’s made of borosilicate glass, 16 ounces or larger, and has the ability to be closed but not airtight, makes a good starter jar.

How do I choose what sourdough starter jar size I choose?

It depends on how much starter you’ll be using. If you plan to bake with it once a week for one or two recipes, a 16 oz jar will work just fine. If you make all your bread items from scratch, you’ll want a larger jar so you don’t run out of a starter.

What size Mason jar is best for a sourdough starter?

The best size is a 16 ounce or a 24 ounce Mason jar.

What size jar is best for a sourdough starter?

Any size 16 ounces or larger is best for storing a starter.

Can my sourdough starter container be metal?

It can if it’s pure stainless steel. Just make sure it’s not aluminum. Look for something that is 18/8 stainless steel to ensure it’s pure.

Can you store sourdough starter in an airtight container?

No, you never want to seal the jar or container completely shut. It can explode or burst from the fermentation taking place.

open jar full of starter
Source: Plum Branch Home

Do I leave my sourdough starter jar open or closed?

You’ll want to leave the lid of your starter loose. You don’t want to shut it completely or keep it open all the way.

How to clean my sourdough starter jar?

It’s not necessary to take your starter completely out of the jar and clean it. All you need to do is scrape down the sides and wipe off the rim/lid each time you feed it.

How do I know if there’s mold in my sourdough starter?

If it looks black or pink and/or smells like mildew, it’s moldy. If it’s grey or has a layer of dark grey liquid on top, it’s just hungry.

What to do if there’s mold in my sourdough starter?

If there’s mold in your sourdough starter you need to throw it out and start a new one. But before you toss it in the garbage, ensure it’s mold. If the starter is gray and still smells like normal or alcohol, it just means it’s hungry and needs to be fed.

Here’s the signs it’s moldy:

  • smells musty or like mildew
  • has a pink spots, color, or hue
  • has black spots, color, or hue

Is a glass sourdough starter jar better?

Yes, glass is always better because it doesn’t react with the starter.

What does condensation in my sourdough starter jar mean?

This is normal and isn’t anything to worry about. It can happen if the jar is shut tighter than needed or if your home is more humid. Just loosen the lid a little more to allow the condensation to evaporate.

How often to clean my sourdough starter jar?

You don’t need to clean your sourdough starter jar. Yes, you read that right. Just scrape down the sides and wipe off the rim/lid each time you feed it. That’s all you need to do.

The fermentation of the starter protects the jar from growing bacteria. The only thing you want to watch out for is pink or black mold. If the starter is a gray color it just means the starter is hungry.

How often do you change sourdough starter jars?

You don’t ever have to change your starter jar unless you want to keep a larger or smaller amount.

How often do you feed a sourdough starter jar?

This depends how you store it. You can feed your starter once a week if stored in the fridge or daily if stored on the counter. Check out my post on feeding a sourdough starter for more information.

More Sourdough Explained Posts

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2 Comments

  1. Thanks for write this great article, it’s very helpful! There is a lot of wonderful information in here.