Pay attention to evergreens plants. Evergreens do not go dormant in the winter and are still actively respiring and lose water through their needles. Deciduous trees respire at lower rates in winter.
Since soil insulates and cools down later in the year than the air temperature, roots stay warmer longer and respire at higher rates than the above-ground parts, the trunk, and branches, of deciduous trees after their leaves drop.
Only water when the temperature is above 40°F. In some places, that could be as late as the end of December. That last good watering is an important one.
Stop supplemental watering after the ground freezes because at this point the trees cannot absorb water through the frozen soil.
Other Helpful Resources:
Winterize Your Trees, The Education Store, Purdue Extension’s resource center
Why are the Gingko Leaves Not Falling, Purdue Extension-Forestry and Natural Resources Got Nature? Blog
ID That Tree Winter Edition: Alternate Leaf Arrangement – Black Walnut/Eastern Cottonwood, FNR Got Nature? Blog
ID That Tree Winter Edition: Opposite Leaf Arrangement – Ohio Buckeye/Red Maple, Purdue Extension-FNR YouTube Channel
ID That Tree Winter Edition: Alternate Leaf Arrangement – Honey Locust/Burr Oak, Purdue Extension-FNR YouTube Channel
How do Trees Use Water?, Purdue Landscape Report
Planting Your Tree Part 1: Choosing Your Tree, Purdue extension-FNR YouTube Channel
Tree Installation: Process and Practices, The Education Store
Lindsey Purcell, Urban Forestry Specialist
Purdue University Department of Forestry and Natural Resources