The answer to 'when to tree' is that the best time to plant a tree depends on the type of tree and your local climate. In general, the optimal time to plant most trees is during the dormant season, which is typically in the fall or early spring when the tree is not actively growing. This allows the tree to establish its root system before the hot, dry summer months or the harsh winter weather.
For deciduous trees that lose their leaves in the fall, the best time to plant is in the early spring before new growth appears. This gives the tree time to develop a strong root system before the leaves emerge. For evergreen trees that retain their needles or leaves year-round, the best time to plant is in the early fall, which allows the roots to become established before the winter.