I'm in zone 9. Mine never drops leaves until it dies back in the winter...which is pretty much every year. If you are in zone 10 then I would think it ought to keep its leaves. The cold spell this year has mine looking like a Charlie Brown Christmas Tree.

Echo, you said you have purple. I am pretty sure that is a devil's trumpet or a datura, not an Angel's trumpet which is a Brugmansia. If the flower goes up, it is a datura and is an annual and will die off. Save the seeds and replant in spring. :o)

If the flowers hang down as if a trumpet was being blown from heaven, it is a brugmansia. Datura's look like a trumpet being blown from h---.

Thanks Katkin! I knew there were two varieties, but when I did an image search, pics of both varieties showed up as both Datura and Brugmansia. The ones dropping their leaves are the one with upright flower, I didn't realize it was an annual. I'll cut them back and save those seed pods.