If you have an outdoor composting system, the safest option is to move it indoors or into a warm garage during the winter. If that is not an option, many subterranean systems, such as the Subpod In-Garden Compost System, are partially buried beneath the soil line, which may provide adequate insulation for your worm farm as worms will bury themselves deeper to stay worm. To increase the chances that your worms make it through the winter, try covering your bin with blankets, bales of straw or hay, or other insulating materials, and locate your bin in a sheltered location. Despite your best efforts, if you have a particularly cold winter, your worms may die off, but any eggs they laid should emerge in spring to restart your worm farm all over again.