Gibberellins production occurs mainly in the roots and young leaves. Little growth actually occurs in the root but mainly in the leaves and stems. Even though there is little effect on the root growth, the gibberellins stimulate growth in the stems and leaves. Inside the stems the gibberellins stimulate cell division and cell elongation. Both auxin and gibberellins have to act together in a growing stem.
Gibberellins generally have no influence on plants of normal size.
Yet if a dwarf plant has gibberellins added to it, then it can grow to normal size. In the development of fruit there is also dual control by auxin and gibberellins. There are fruits that require both hormones to be set. The main time gibberellins spray is used, is on seedless grapes to make them grow further apart. Most seeds have a high concentration of gibberellins in the embryo.