How Big a Hole??

[planter]

I know the rule of thumb for most trees and shrubs is to plant them at ground level or slightly higher and that works for me so I understand digging the hole the same depth as the root ball or pot and just loosening the subsoil.

My really question is this... Why do they say on a label to dig a hole the same depth but only 2 or 3 times as wide. I tend to make WIDE hole but not deep ones so whats the scoop. I alway incorporate a lot of native soil in but why does it matter all all how big around your hole is??? I just figure it gives the roots more places to go and most trees are pretty shallow rooted anyway.. Just observe trees blown over by the wind..

[Marlingardener]

I think the reason behind recommending a hole two or three times as wide as the root ball is to provide loosened soil for the feeder roots. Most trees have a tap root that goes deep and lots of feeder roots that are closer to the surface and absorb water and nutrients. It's just easier for the feeder roots to get established if the soil is loose to start with.
What kind of tree do you want, deciduous or evergreen? What size, and where is it going to be planted? When we lived up north, I was always partial to maples, until it came time to rake up all those big leaves, that is!