Hanging wreath on fiberglass door?

Hi Nancy, they make over the door wreath hangers :)

You can use a long wide ribbon (about a yard) loop it around the wreath and attach the two loose ends to the top of the door with a tack or short nail.

http://makelyhome.com/how-i-hang-wreaths-on-my-front-door/

Use an over the door hanger or use a ribbon tacked on the inside folded over the top of the door

You did mention it's fiberglass. My door is also fiberglass. The perimeter edges are wood and fiberglass skins are bonded to them. Where the hinges are attached, locksets, top, and bottom.

The command hooks supposedly can be removed without damage. I have one for wreaths on mine but have never tried to remove it.

I use an over the door wreath hanger on my fiberglass door!

Hang a command hook on the inside of the door but do it upside down. Make a giant loop out of ribbon or some other material that can be ran from the wreath, over the top, and hooked on the command hook.

I am in Alabama where there is high humidity and command hooks will give way eventually and come unstuck. I have one door that has no cover and the command hook didn't do well there even using an outdoor version. This has done very well and has enabled me to hang a wreath on both doors.

Note that if your door is sealed tight, those metal over the door wreath holders can damage the gasket or the trim around your door.