Green Bay, Wisconsin is in USDA Hardiness Zones 5a and 5b.Click to see full answer. Furthermore, what zone is Wisconsin in for planting?Wisconsin has three cold hardiness zones – Zone 3 (Northwestern WI), Zone 4 (North, Central, Western WI) and Zone 5 (Southern and eastern WI up past Green Bay and Apostle Islands).Likewise, what zone is Wausau WI? 4b Likewise, how do I find my growing zone? If you see a hardiness zone in a gardening catalog or plant description, chances are it refers to this USDA map. To find your USDA Hardiness Zone, enter your zip code or use the map below. Click here for more information about hardiness maps. Find your zone using the map below or enter your zip code.When can you start planting in Wisconsin? for Southeastern Wisconsin. In Late March or Early April, sow seeds indoors of: In Mid- to Late April, sow seeds indoors of: In Late April, sow seeds directly into the garden of: In Early May, transplant plants into the garden of: In Mid-May, sow seeds directly into the garden of: