The Hardiest of Hardy Perennials. Generally speaking, a plant is classified as a perennial if it can survive to Zone 7. Above that range, plants become tender perennials or annuals. For the purpose of this article, we will only consider the "hardiest" of hardy perennials, plants that are hardy to Zones 4 and lower (or higher in latitude). The plants on this list are definitely tough enough to survive your area's worst winters.
If you’re growing purely for pleasure and want dahlias that look great in the landscape, then these guys are for you! Even if you don’t have a lot of space to devote to them, you can still enjoy these wonderful plants in pots or tucked into your existing garden, plus be able to pick from them and bring flowers in the house.