Question
I have 5 white pines(7 ft. 4.1/2 in diameter) and a nellie stevens (5 ft) that i purchased this late spring early summer.  they are doing well but now (due to setback requirments need to be moved.  **  I would like to raise them up in planter boxes. However, I do not know if this is a good idea as they are or will be big trees.  What are your thoughts on this...

Answer
I do not think it would be a good idea--these trees are too large for planter-the planter would have to be very large. The root ball of a tree should be  
Width = 9-12 in. in diameter/every 1 in. of tree diameter
Depth = 6 in./every 1 in. of tree diameter

For example: A tree trunk 4 inches in diameter would need a root ball of 36-48 inches wide and 24 inches deep.

As the tree grows you can calculate the planter size. Trees like white pine are made for planters. The Holly may do ok but still will need a very large planter. The root spread of a tree is about 1 1/2 times the area of the foliage to be able to meet the requirements for water for the tree. Trees this size should not be planted in planters. My opinion!