Watch this video from This Old House to learn how to plant a tree in poor soil.
1 Select spot for tree away from house and overhead wires.
2 Measure diameter of the plastic tree pot.
3 Dig a hole four times wider than pot and as deep as the pot.
4 Add compost to topsoil; mix with shovel.
5 Set tree in hole; lift up and pull off pot.
6 Rotate best face of tree toward street with main branches parallel with house.
7 Scratch root ball with cultivator to loosen roots.
8 Add starter fertilizer and superphosphorous to topsoil.
9 Backfill around tree with amended topsoil.
10 Form 4-inch-high ring of soil around tree, fill with water.
11 Stake tree with wires; wrap garden hose around wire to protect tree bark.
12 Add 2 or 3 inches of bark mulch; keep mulch away from trunk.
13 Wrap drip-irrigation bag around base of tree; fill bag with water.
14 Refill the bag with water twice every week until the root system is established.