Making sure your trees are properly watered in autumn will help prepare them for a safe winter. In the middle of winter the ground is frozen and trees are not able to access water. In early autumn you should stop watering your trees. If trees are still growing and frost comes early the trees could be permanently damaged. If you continue to water at this time you are encouraging new growth.
Once the trees have lost their leaves it is time to start watering again. By late autumn the tops of the trees have gone dormant and will not be producing new growth. Water deeply before the ground freezes, which encourages proper root growth. Evergreen trees will definitely need a lot of water, as will young trees. Keep watering through late autumn, as long as the ground is not covered by snow and the air temperature is above 45 degrees.
If you are looking to move trees, autumn is an ideal time to transplant them. The soil is usually moist thanks to rain showers and the ground is still warm from the summer. Transplanting at this time allows plants time to settle into their new home and form roots prior to the cold winter months.