The answer to 'when to tree' is that the best time to plant trees depends on the climate and tree species. In general, the ideal time to plant trees is during the dormant season, typically in the fall or early spring. This allows the tree's roots to become established before the hot, dry summer months or the cold winter weather.
For most deciduous trees, the best time to plant is in the fall, after the leaves have dropped. This gives the roots time to grow before the tree begins budding in the spring. Evergreen trees, on the other hand, are best planted in the early spring, before new growth begins. Planting during the dormant season reduces transplant shock and gives the tree the best chance of survival and thriving in its new location.