Generally speaking, shrubs and trees that are planted too deeply will suffer from stunted growth. Here in Florida it is common to seek identical palms for each side of the driveway. If the landscape company has two of differing heights, they may plant the taller one deeper to compensate. Five years later, the properly planted one is much taller and more robust than the other. Your plants should be planted at the same depth as they were in the container or slightly higher. I have some expensive plants on top of slight mounds to guard against settling. It is worth the time and money to raise those you suspect of having this problem as it will not get better, only worse.
Jim
