Unfortunately Wisconsin is way too cold to even consider growing palm trees. Wisconsin has a mainland atmosphere with warm summers and cold winters. It is impacted by Lakes Michigan and Superior. The normal temperature in July goes from 68°F (20°C) to 80°F (27°C). In January the normal temperature ranges from 8°F (– 13°C) to 26°F (– 3°C) contingent upon the area.
Parts of the northern part of the state only get 80 frost free days per year! Other parts of the state double that figure. Wisconsin USDA zones 2b to 5a.
Palm Trees in Wisconsin
Your only real chance at enjoying palm trees here would be to have them in pots or planters, and bring them inside during the winter months. Some extraordinary indoor/outdoor palms are:
Areca Palm Tree – Zones 9a – 11 (20 to 25 F)
Chinese Fan Palm Tree – Zones 8a – 11 (10 to 15 F)
Kentia Palm Tree – Zones 9b – 11 (25 to 30 F)
Lady Palm Tree – Zones 8b – 11 (15 to 20 F)