If you have done the above (and are in the northern hemisphere), your tree is still in a period of establishing. When a tree is established it has the roots system of a 'natural' tree and can look after itself.
This period of establishment can last for upto 5 years (and where there is competition from adjacent mature trees or the planting location is poor i.e. lack of rooting space, hard landscaping around the tree, surrounding poor soil, the trees could require assistance for longer).
This length of aftercare is recognised by BS8545:2004. It is appalling that no planning authorities are enforcing this (a far as I am aware).
The assistance required is primarily watering to compensate for the reduced root system, but also includes removal of epicormic/basal growth and should include mulching (see previous blogs).
Transplanted and planted trees must have this assistance whilst establishing, after the investment in trans/planting, this will almost guarantee the success of your trees.