Dahlias are native to Mexico, and they like warmth and sun, so they will overwinter in warmer areas. Here in Michigan, tubers must be dug and stored indoors. They do not like the frosty winters here!  So, they are not perennial here in the growing zones here.  But you can dig the tubers up each year, and bring them into an unheated room or place that doesn’t freeze to save them for next year.  It does take some learning and experimentation to figure out a system to store dahlia tubers that works best for you, but it is a great way to keep your dahlias for the coming year, and to increase them, as one dahlias tuber can make more during the growing season.  One tuber typically makes 4 or 5 more, so you can divide tuber clumps and have additional dahlia plants for next year.  Dahlias make great gifts for your gardening friends!  

Happy planting!  Jaye