Most of us are familiar with the Hardiness Zones Map and perhaps even have used it when picking new plants for our gardens. A Hardiness Zone Map is based on average winter temperature.
However, to be most successful with your native gardening, the plants and seeds you use should originate in a geographic section or at least a province similar to the ecoregion into which you intend to introduce the plants. For that reason, I’d like to suggest referencing an Ecoregions Map as a basis for selecting native plants rather than a Hardiness Zone Map. An Ecoregions Map takes into consideration a variety of characteristics in creating a land description. Plants surely are temperature sensitive, but they also are sensitive to the amount of water and sunshine available and the type of soil and even the insects.
The US Department of Agriculture’s Forest Service has created maps showing the main ecosystems found in the continental USA. There are four levels of regions with the largest being Domains grouped by climate and then by precipitation and temperature, and the smallest being Sections grouped by precipitation and temperature, and also land forms, land use, geology, soil, vegetation and even wildlife — everything required to maintain biodiversity and to continue evolving.
Southeastern Wisconsin Lacustrine Clay Plain
Here in the Fox Valley of Wisconsin we are in Ecoregion Section 53d Southeastern Wisconsin (or Lake Michigan) Lacustrine Clay Plain. It is “characterized by red calcareous clay soil, lacustrine and till deposits, and a flat plain. The topography of this ecoregion is much flatter than ecoregions to the south, and there are fewer lakes, but with the lakes have generally higher trophic states, than in adjacent level IV ecoregions in (50) and (51). Soils are generally silty and loamy over calcareous loamy till, with muck and loamy lacustrine soils in low-lying areas. Ecoregion 53d has prime farmland with a longer growing season and more fertile soils than surrounding ecoregions. Agriculture has a different mosaic of crops, with more fruit and vegetable crops, than that of Ecoregion 53c. The PNV (potential natural vegetation) of this region is beech/sugar maple/basswood/red and white oak forests with a greater concentration of beech than other ecoregions in 53.” (WDNR Ecoregions of Wisconsin)
Ecoregion Interactive Gardening Maps & Guides
Plant Maps has a series of USEPA Ecoregion Interactive Gardening Maps by states. Go to Plant Maps and in the right column you’ll see a list of adjacent states. Here’s where you’ll also find a link for a state’s Interactive Maps of Native Trees and Plants.
Pollinator Partnership also maintains a list of Ecoregional Planting Guides.
A successful native gardener will take all the elements of biodiversity into consideration and then plant a species that will not be out of place. Using ecoregions maps will be the surest way to success.
Ecoregions Map Level IV Sections Note: This is a huge file, so give it time to upload.