Planting in spring gives a new tree, and some shrubs, a chance to grow all summer and get ready for winter.  Planting in the spring allows the plant to acclimate to the new soil and avoid plant stress.

After planting, leaves develop and they are able to make food for the plant all summer.  When a trees and shrubs are planted they need to make new roots. Planting in spring means that the tree needs to make new roots at the same time as it makes new leaves.

Both of these growth processes require sugar reserves that are stored in the roots, and stems.  This is a critical time and care must be taken to avoid over and underwatering. Sufficient plant food for new growth is a MUST.