I used E6000 to glue the metal threaded 1" hex nut to the glass plate back In a vertical position. I let it dry 24 hours before threading the rebar into the hex nut and placing the completed flower in the landscape. I also used the same E6000 to glue the various glass pieces together. Has held up well so far!

E6000 is one of the best glues around, but I've read that it isn't UV resistant so I've stuck with silicone II for windows and doors. Works for me for the last 3 years.

I found UV6800 that works the same as E6000 but doesn't discolor in the sun, made by the same company. It's hard to find though. The first time I bought it I got it online from AFTOSA at $5.99 a tube. I finally found it at an ACE Hardware store too but it was $7.99. I also researched how long it stays good in the tube and should be used in 2 years so check the date on the bottom of the tube. I've used it after the 2 years and it seems to be holding up just find. I first made plate flowers and totems 5 years ago with E6000 and they are still holding together but of course the glue has discolored.

Today I used E6000 for the first time in a long time. They fumes nearly did me in even with the window open.

The first BB I made was with GE clear silicone II, for windows and doors, about 15 years ago. It has been through hurricanes, hail storms and all kinds of hot and cold weather (ice storm this past winter) and it is just now beginning to 'lose its marbles' I also have totems that have been out for about that long. I made those before they were called 'totems' LOL
I believe in this type of silicone.