Chelle ...
Roses are survivors and really do want to grow ...seems that's how mine have survived my mistakes ...
You said "It came out of too-dry soil with only two roots, "
I may be interpreting what you wrote wrong, but if I am, please forgive me. A good rule of thumb is to always water a rose well before you transplant it. This hydrates the plant well and helps reduce transplant shock. Also, you can get more of the root mass out easier.
Smiles,
Lyn
