Growing a eucliptis tree in TN

Found this little 8" grey plant on $1 shelf in back of Home Depot. Planted it in garden last summer. Didn't know if it was perennial or not. It not only survived it grew to 6 feet over summer. It is planted in my garden next to the porch. From research I believe it to be eucalyptus, which can grow to 50'-60' but has a habit of dropping limbs. My husband just cut it short, like bonsai, and we are thinking of leaving it where it is as eucalyptus is supposed to repel insects. I cannot find any info on what the roots might do. Will they also stay compact or will they continue to grow under 10' porch toward house.