my guess is transplant shock, did you just plant it outside? that usually happens unless your super carefull with the rootball. it goes away in a few hours.
Ive read that when you first put them outside the difference in light intensity can cause the plant stress. They are supposed to recover in a few days. If u just transplanted from indoors this could be the case.
the dirt could be really bad too. bad dirt that doesnt drain well usually clumps up and becomes hard muddy like dirt that makes it hard for roots to grow out. did you use the native soil where you planted or did you mix in anything to the dirt? perlite? peat moss? etc...