You have a few options.
You can "plant" it, with layers of hydroballs, sand, and dirt.
You can drill through the glass(using a glass drill bit, Ive drilled through glass with regular bits, but its "tricky")
or(this is what I would do) you can take a hammer to the bottom, and "remove" the entire glass bottom. Then get a sheet of pvc/plastic/plexiglass and put it on the bottom, and drill holes in that.