Since it has been inside for an indeterminate amount of time, consider it to be like any other plant which needs hardening off before planting out. On days which are above 40 degrees Farenheit, you may set it outside under partial or filtered sun. Gradually, increase the amount of sun to full sun, this will allow it to get all the sun it likes without burning it until it adjusts. Do not leave out yet when the temps. dip below 40. Eventually, especially if the pot is sunk into the ground, it will be able to stand the lower range temperatures, but this is not a bonsai, and was not meant to be left out to go dormant over the winter. It will appreciate the chill and shortened day lengths in the fall, and will reward you with flowers if you allow it to leave it's strictly sheared boundaries.