We live on the north Green Bay area Wisconsin, when is it too late to plant trees in the fall for them to get root establishment for winter?
Oconto County Wisconsin
Fall planting is fine, but don't allow the roots to freeze by planting on a day with temperatures close to freezing. Watch the trees to make sure the roots stay covered with soil. Frost in the ground can cause the soil to heave, exposing the roots. You may need to stake fall planted trees to prevent tipping. The trees will continue to develop roots and become better anchored during the winter. The soil should be kept moist, but not soggy.
Late fall planting is not a good idea if the trees are still growing at the time of planting and there happens to be a rapid temperature drop to the teens.
If you plant a tree with a root ball, fall planting is less tramatic to the tree.