How to Keep Sourdough Starter Warm (2021)

by Heather

Maintaining a sourdough starter is a wonderful hobby. We go to great lengths to take care of our starters, so how can we keep our sourdough starter warm in a cold house?

Many home bakers deal with this conundrum each winter, and find themselves stumped when their starters won’t rise or double like they used to. Some home bakers are even afraid to store their starter in the refrigerator because it takes so long to reach peak activity once removed from the fridge, due to a cool indoor environment. I’ve talked to dozens of home bakers who faced this challenge and came up with innovative ways to keep their sourdough starter warm, and I’ve compiled those ideas into one convenient list. If you’re struggling with keeping your starter warm in the winter, this post is for you!

This post contains affiliate links. For more information, see my disclosures here.

How to keep sourdough starter warm during cold winter months


  • Keep your starter on a seed mat. This is a great way to keep the starter at a constant warm temperature, and it’s especially helpful to bring it back to life after pulling it from the fridge in a cold house.
  • Some bakers use a toddler size fleece hat to keep their sourdough starter warm by wrapping it around the jar. Substitute with any warm garment or towel. If that’s not enough, you can warm up a pad in the microwave or use a heating pad set to warm or low on the outside of the fleece.

  • USB mug warmer – the perfect size device to warm your starter, with a temperature setting to help you get the right warmth.
  • The cheapest, quickest fix? Place your starter in the microwave with the door just barely shut so the light stays on.  The small space with the light on can warm up the area enough to help the starter grow.

  • Use a reptile heating lamp to help keep your sourdough starter warm. Some people will make a little wooden box with a glass or plastic door to see through to the starter. Some heating lamps, like this one, have a built-in temperature setting.

  • Depending on your stove and stove top, some people have been able to warm up their starter by turning on their stove and placing the starter on the stove top, taking care to use the lowest setting and to shut off the heat once the element is warmed.

  • Use a rice heating pad that can be warmed up in the microwave. The rice filled pad stays warm for a while and can be wrapped around your starter to help keep it warm. The pad can also be used for aches and pains!
  • Boil water in a small pot or your dutch oven and put that into the oven with light on. The yeast loves it, and it’s an inexpensive way to keep your sourdough starter warm. Not only is it warm in the oven, but it’s humid, too!
  • Put a cup of water in your microwave and boil the water. It heats up the microwave and then makes it like a proofing box. Put your starter next to the hot water and keep the door closed. It warms the microwave up surprisingly well. You might have to reboil the water every few hours but it might get your starter going.

  • Set your starter next to a lava lamp and turn it on. Warm your starter and get groovy!
  • Put the starter on the counter above the dishwasher running on a high temp. Depending on the thickness of the counter, this could keep your sourdough starter warm as the counter warms up from the heat of the dishwasher.  

  • Use a folding bread proofer to keep your starter warm. This is a pricey option, but you could also use the box as a bread proofer, thereby making your bread-making life easier as well!
  • Is it the holidays? Try wrapping mini Christmas lights around your starter jar! The warmth from the Christmas lights should radiate into your starter, keeping your sourdough starter warm.

  • Place your starter on an aluminum griddle that sits on the stovetop. If you have a non-LED hood light above the stove, turn on the light. The aluminum griddle will attract the heat from the light and dissipate the cold. 
  • Try using a desk lamp over a little box to trap the heat and keep your sourdough starter warm!

  • Use a little space heater with a temperature setting. I actually use this trick to keep my indoor plants alive and thriving in my sunroom, which is poorly insulated and gets very cold in the winter. I have the space heater set to keep the room at 65 degrees, but there are higher temperature settings that would work well to keep a room warm enough for starter.

What did I miss?

Do you have an ingenius way of keeping your starter warm that you didn’t see listed here? Leave me a comment or send me an email at heather@leavenly.com – I’d love to hear from you!

Struggling with other issues? Check out my helpful post, Sourdough Starter Problems, to find some answers to your starter challenges.

Curious about hydration? Learn all about it here, on The Beginner’s Guide to Sourdough Hydration!

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