so would it significantly affect my grow if my seedling was planted 2 or 3 feet away from a large tree? like would the roots of the tree prevent my seedling to have adequate growth?
if you dig a 3 by 3 hole in the ground and fill it with potting soil right next to the tree you should be fine.
if you dug the right size hole then you would have removed any roots in the way and you will be fine like someone said above, if you didnt and you just planted then of course it is a POSSIBLE problem if you grow in the right size hole then your roots wont go far past that if at all