Autumn and winter present special challenges for culturing. As the weather cools, the methods for keeping cultures at the proper temperature must also change and adapt especially here in the UK when the weather can change dramatically from one day to the next.
Some cultures will actually behave differently during the winter even when the amount of light and heat are constant, they can change their shape, size and texture and you may notice that the taste also changes slightly.
How Can You Keep the Cultures Warm Enough? A heat tray may help.
There are a variety of ways to help keep cultures warm enough to culture well during cooler weather. No matter the method you choose, it is important to verify the temperature. Test the temperature by leaving a jar of water for at least an hour, then taking the temperature of the water or using a stick on thermometer.
We do not recommend using a heat method for milk kefir as it can often be too warm for the grains and can kill them. Instead it is best just to reduce the amount of milk slightly and brew for a little longer.