What Jar Should I Use for My Sourdough Starter?

The jar you keep your sourdough starter in has a bigger impact on your baking experience than most beginners expect. A good jar makes feeding easy, rise-tracking reliable, and maintenance simple. A poor choice — usually a jar that's too wide or too large — can make a healthy starter look inactive, which leads to confusion and unnecessary worry. This guide covers the basics for beginners.

Why the Right Jar Matters

The most common reason beginners think their starter isn't working is that they can't see it rising. In a wide bowl or a large mason jar, even a healthy, active starter only adds a centimetre or two of visible height because the same amount of gas spread across a wide surface produces almost no visible rise. In a narrow, tall jar, the same amount of gas pushes the starter significantly higher — making the rise obvious and satisfying to track.

If you're not sure whether your starter is active, the first thing to do is transfer it to a narrower container. You may find it was rising all along.

What to Look for in a Starter Jar

• Narrow profile: Taller and narrower than wide. The internal diameter should be small enough that 100g of starter is at least 3–4cm deep.
• Clear glass or plastic: So you can see the starter and any bubbles forming at the sides.
• Suitable size: For a standard home baker's maintenance quantity of 75–150g, a 400–600ml jar is ideal. Enough room for the starter to double without overflowing, but not so large that it gets lost in the jar.
• Loose-fitting lid: The starter produces CO2 and needs to breathe. A tight lid can build pressure. A loose lid, cloth, or the lid slightly ajar works well.

Our 500ml sourdough starter jar is designed with all of this in mind — narrow profile, borosilicate glass, measurement scale on the glass, and a loose-fitting lid included.

How to Track the Rise

After each feeding, mark the starting level so you can track how much the starter rises:

• Rubber band: Wrap a rubber band around the outside of the jar at the exact level of the starter after feeding. When you check later, if the starter is above the band, it's risen. If the band is at a "tide mark" (a ring of dried starter above the current level), the starter rose and fell while you weren't watching — that's a perfectly healthy starter.
• Wax pencil or whiteboard marker: Mark directly on the glass. Wipes off easily when the jar is cleaned.
• Measurement scale: Our jar has one printed on the glass — you can record the starting level and percentage rise directly without any additional tools.

How to Clean the Jar

Clean the jar every 1–2 weeks during regular use:

1. Transfer the starter to a temporary bowl or another jar
2. Rinse the jar with hot water only — no soap. Soap residue can harm the starter culture.
3. Scrub any dried starter from the sides with a brush and hot water
4. Dry thoroughly, then return the starter

It's normal and fine for starter to build up on the sides of the jar between cleanings — it doesn't affect the health of the culture.

Do You Need a Special Jar?

You don't need to buy a special jar to keep a sourdough starter. A clean glass jar from your kitchen will work. The difference is convenience and visibility. If you're finding it hard to tell whether your starter is active, a purpose-built narrow jar removes a lot of guesswork from the process. Our jars also come with the starter — so if you're buying a starter from us, you can add the jar at the same time and start with everything set up correctly.

For the full starter care routine, see our Step-by-Step Starter Feeding Guide.