I don't think it takes much of a frost to kill mandevilla so your garage might get too cold. I've overwintered one in my house several times by a south window. The vines are pretty long by spring.

thanks christie.
i noticed tubers in the rootball. if you trim a couple off and plant, will a new plant come forth or do you propagate by cuttings? i took about 5 cuttings.

william