I would go with a manmade product for ease of maintenance but not sure where you are planning to put this.

Thank you. I mentioned the arbor will be above garage doors. For clarity, what did you mean "not sure where you are planning to put this"? It will be facing North, and with surrounding trees & weather, we do get moss on our driveway & entrance steps, which requires power washing twice a year. I'll ask a contractor if flashings are necessary (to protect wood & siding), because we do not have an overhang/awning above the garage doors. Is this why you mentioned "manmade product"? Thanks again for your advice.