Ask Mr. Smarty Plants

The windmill palm (Trachycarpus fortunei), is also referred to as Chinese Palm. This Sun Palm Trees website Windmill Palms - Cold Hardy Palms says it is the most cold-hardy of palms. However, this Floridata site on Trachycarpus fortunei states that the acceptable zones for this plant are USDA Hardiness Zones 7b to 10, and that it should be in a sheltered spot in Zone 7. Sterling Heights MI appears to be in Zone 5b to 6a (average minimum temperature -15 to 0). If the plant is in a sheltered area, with its roots in the ground (where they will be warmer than in a pot) you might be able to pull it through by covering it. If you have it in a pot, it should be brought indoors and kept in a bright window until the temperatures start to go up.

All this having been said, we wish you would plant something else. The Lady Bird Johnson Wildflower Center is devoted to the care and propagation of plants native not only to North America but to the area in which they are being grown. Plants native to your area would already be acclimated to the normal climactic conditions, soil and rainfall. With a quick scan of our Recommended Species for Michigan, we found 4 shrubs that would do very well there, are native to Michigan, and wouldn't require an electric blanket in the winter: Arctostaphylos uva-ursi (kinnikinnick), Ceanothus americanus (New Jersey tea), Amelanchier arborea (common serviceberry) and Cornus sericea (redosier dogwood). If you get tired of keeping your palm warm enough to survive or if it doesn't survive, you might consider one of these suggestions or some other shrub native to your area.

Arctostaphylos uva-ursi

Ceanothus americanus

Amelanchier arborea

Cornus sericea