Mums, or chrysanthemums, are hardy plants that can tolerate cool temperatures fairly well. However, they are not immune to frost, and just one frosty night can damage them. The lowest minimum temperatures that mums can survive are right around minus 20 degrees Fahrenheit, according to the USDA map. However, this only applies to hardy garden mums, and potted mums are more susceptible to damage from cold temperatures. Potted mums purchased at a nursery, garden center, or grocery store can survive in temperatures that dip down into the 20s and can handle an occasional light frost in a pot. However, they wont tolerate cold temperatures very well, and its best to bring them inside when freezing temperatures are expected. According to a gardening expert, potted mums won’t be affected by frost until the temperature drops to 28 degrees or 26 degrees. Therefore, its important to check the weather forecast and take necessary precautions to protect mums from frost and freezing temperatures.