One of the most common ailments of potted plants is the "soil" they're in. If it's potting mix (not real soil) it can get hydrophobic, which means as fast as your water the top it comes out the bottom as the "soil mix" repels water.
If this is the case and you dont want to buy commercial wetting agents to add to the water just ad a few drops of dish washing liquid or soap ... it'll do the same thing.
Over watering propbably kills more potted plants than under watering. Depending on the future location for the trees you decide whether to sun harden or shade them. But dont keep them shaded then plant them in full sun on their debut from the pot!
Fertilize with liquid organic, like blood/bone or dynamic lifter. Dont go loading them up with nitrogen coz they're trees not vegetables.
