When your pecan seedling is ready to be transplanted from the germination container to the pot, choosing the appropriate pot size is important. You will need a pot that is wide enough to accommodate the rootball without having it wind around itself. It should be deep enough to allow the tap root to grow long and straight. Pecan trees develop deep roots and require lots of space, so you will need to transplant it into the garden when it reaches 2 feet in height, or when the roots begin to grow out of the pot.
Pour moist potting soil into the pot so that the pecan tree will sit at the same depth at which it has been growing.
Remove the pecan tree from its current container being careful not to disturb the roots. Place the roots on top of the soil in the pot and backfill until the pot is 3/4 of the way full with soil.
Fill the pot with water, allow it to drain, and finish filling it with soil. Use your hands to gently press the soil around the base of the pecan tree. Water the tree until the water runs out of the bottom of the pot.