yes you can leave them, and mother nature will do the work. But their are some things that I would do.

The roof could get pretty hot, which will be bad for the roots. Is there another place you could put the plant outside. I would transplant to a 5 gallon bucket, and put the plant in the woods.

Make sure you paint the bucket to match wherever you decide to put it, and have drainage hole's atleast an eigth of an inch thick.