If you’ve ever stood in your kitchen holding two different sourdough starter lids wondering which one you’re meant to use, you’re not alone.
In fact, this is one of the most common sourdough starter mistakes I see, especially with newer bakers (and yes, gluten-free bakers too).
The good news?
Once you understand this one simple rule, sourdough starter care becomes so much easier and a lot less stressful.
Let’s clear it up properly.
Why Your Sourdough Starter Lid Actually Matters
Your sourdough starter is alive.
It’s a living culture of wild yeast and bacteria, and how you store it directly affects:
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Fermentation strength
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Rise and activity
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Smell and stability
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Overflow and mess
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Long-term starter health
Using the wrong lid at the wrong time can lead to pressure build-up, sluggish fermentation, strange smells, or starters that go mouldy.
But here’s the key thing most people aren’t told:
👉 Your sourdough starter has two different modes and each one needs a different lid.
Your Sourdough Starter Has Two Modes
1. Active (On the Bench)
2. Resting (In the Fridge)
Once you understand which mode your starter is in, the lid choice becomes obvious.
When Your Sourdough Starter Is ACTIVE (On the Bench)
Your starter is considered active when it has been freshly fed and is sitting out on the bench fermenting.
This is when it’s:
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Bubbling
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Rising
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Doubling in size
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Preparing to bake with
At this stage, your starter needs airflow.
The correct lid to use:
✔️ Linen cloth cover
Why this matters:
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Allows natural gases to escape
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Prevents pressure build-up
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Supports healthy fermentation
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Reduces the risk of overflow
If your starter is alive and active, sealing it completely can trap gas and interfere with its natural rhythm and it can go moldy.
An active starter wants air, not a tight seal.
When Your Sourdough Starter Is RESTING (In the Fridge)
Once you’ve finished baking and your starter has:
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Been fed
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Risen alittle (2hours max on bench so its stored at its peak)
…it’s time for it to rest.
This is when your starter goes into fridge storage between bakes.
The correct lid to use:
✔️ Glass or silicone lid
Why this works:
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Seals and protects your starter
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Prevents fridge smells entering the jar
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Slows fermentation safely
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Keeps moisture levels stable and prevents its from going mouldy
Think of this stage as your starter “going to sleep”.
A resting starter doesn’t need airflow, it needs protection.
The Easiest Way to Remember (Bookmark This)
✨ Active = breathable
✨ Resting = sealed
Or even simpler:
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Bubbling on the bench → linen cloth
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Sleeping in the fridge → lid on
This one rule alone solves a huge amount of starter confusion.
Common Problems This Fixes Immediately
If you’ve experienced any of the following, lid choice is often the culprit:
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Starter overflowing unexpectedly
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Strange pressure or popping sounds
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Starter smelling off when it shouldn’t
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Mould growing even when starter is being fed on the bench
Correct lid use helps your starter behave more predictably and makes it easier to know when it’s ready to bake.
Does This Rule Apply to Gluten-Free Sourdough Starters?
Yes — 100%.
🌾 Gluten-free starter note:
This lid rule is exactly the same for gluten-free starters.
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Active on the bench → linen cloth (breathable)
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Resting in the fridge → sealed lid
Even though gluten-free starters often ferment a little faster and can appear wetter, the same airflow vs sealing principles apply.
Different flours — same starter care.
Why This Matters for Beginner Sourdough Bakers
Sourdough doesn’t need to be complicated but it does need clarity.
Understanding something as simple as which lid to use and when builds confidence quickly and prevents many of the frustrations that cause people to give up too early.
Once this clicks, everything else becomes easier to read:
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Fermentation timing
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Starter strength
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Baking readiness
Final Thoughts
If there’s one thing I want you to take away from this:
Your starter isn’t fussy, it just needs the right environment at the right time.
Active starters breathe.
Resting starters seal.
I cover this in much more depth inside my sourdough ebook and workshops, alongside feeding schedules, storage tips, and troubleshooting but I wanted this to live here as a resource you can always come back to.
Save it. Bookmark it. Share it with a sourdough friend 🤍
And remember, you’re doing better than you think.
Warmly,
Kayla
The Sourdough Way