Keep ’em Cozy, but Don’t Cook the Kefir Grains!

jars in oven

Note from Shannon: Please welcome Bonni, Cultures for Health Customer Service Rep and Cultured-Kitchen Keeper.

When the seasons change and the weather begins to cool, we have to get creative with keeping appropriate temperatures for our cultures. I keep my house relatively cool in the Autumn and Winter months ~ 67ºF(19ºC) during the day and 63ºF(17ºC) at night. We stay cozy in sweaters or blankets, but cultures have a bit of a harder time.

So, here’s what works to keep my cultures cozy…


After testing my oven, I found that it maintains a beautiful 77ºF(25ºC), perfect for culturing my water kefir. This has been my “go to” water kefir culturing spot for years now. This Autumn took a little longer to cool off, but we did hit those cool temperatures and my house is feeling pretty chilly if you’re a kefir grain.

After straining the grains and putting them in fresh sugar water, it was time to move them from the high cupboard to the oven with the light on. They were happy culturing away.

I always put a note on my oven controls (and advise customers to do the same) so I don’t turn the oven on with the grains inside. Well, not always. One time, I forgot…and heated my grains in a 375ºF(190ºC) oven. Not good!

oven sign

So, my friends, please remember to take preventative measures and don’t cook your grains!



Bonni started on the cultured foods path quite few years ago, beginning with sauerkraut. Since then, she has cultured yogurt, milk kefir, water kefir, kombucha, a variety of veggies, sour cream and gluten-free sourdough. She is a busy homeschool mom to her daughter, so is always looking for the most efficient and least time consuming ways to manage all of her culturing.

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  1. MantanCalaveras says

    Seems wasteful to run the oven nonstop.

    I keep my kombucha in a cabinet above my refrigerator, which stays about 78°. The refrigerator needs to stay on 24/7 anyway, so it’s a win win.

    Suppose you could put a towel over the jars too, to trap more of the heat.

    • says

      Mantan – I believe you misunderstood Bonni. She does not run her oven at all. The temperature she listed is simply the temperature it stays at because it is insulated from the room temperature.

      She related to me that she has tried testing the temperature above her refrigerator and it stays too cold compared to her oven.

  2. AJ says

    I use my oven to culture yogurt with only the light on so this seems like a great idea especially if you don’t use your oven a lot. Thanks for the tip!

  3. Jim Carver says

    I’m afraid you both have it wrong. The source of heat is the light bulb. You don’t have to use the oven either. You can build a box of some sort and put the right wattage light bulb in there and do the same thing.
    Heat has to come from somewhere and many refrigerators nowadays exhaust the heated air through the bottom of the unit. Unless you want your culture on the floor…uh okay, you get the idea.
    Another thing you can use is a food dehydrator. You’ll have to check it with a thermometer but it should be able to maintain 77F.

  4. Elaine says

    From what I understand…she leaves the LIGHT on in the oven and the warmth of the light bulb is what keeps the kefir warm. Great idea!

  5. Leslie Dolin says

    We keep our house at 68 in the winter, and the furnace is off at night and often during the day. My water kefir stays in the same cabinet above my kitchen counter all year and does great all winter with no added heat.

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