You should expect to be having to provide firm support for tall-growing - or otherwise large-flowered - glads. Do it before the flowers start to open.

Well when I bought the bag it said they'd get between 36-60 inches. I don't really know what a "tall flowering" gladiolus is. I just figured they'd be somewhere between 3-6 feet. I had no idea they'd all be that tall. I've seen pictures of gladiolus growing in fields with zero support. Is there some trick to keeping them upright (other than staking them)?

My gladioli have always flopped over, so I cut the fallen stalks and place them in a vase indoors, while continuing to enjoy outdoors those flowers that have yet to flop. In recent years I have tried sandwiching the glads between the house foundation and this wire garden fence, but this hasn't helped much. Someone told me that she plants her gladioli inside round tomato cages, and that is probably the best solution, because the plants would be supported on all sides.

I, too, have often seen gladioli growing in fields or large gardens with no support, most owned by commercial growers. I'm guessing they may do as I do and harvest the flower stalks (for selling) just as the glads are beginning to, or about to, fall over.

IME with other plants (I don't grow glads) there is a fair range in the relative stem stiffness and flower size. Bigger flowers + less robust stem = floppiness. So in plant types that have the potential to be floppy such as some bearded iris, peonies, or panicled hydrangeas, I try to choose ones with less overblown flowers and that are noted for strong stems, which means choosing specific named varieties with the qualities I am looking for, or else I provide as subtle a support as possible. In this case, a narrow bamboo stake with a plant clip would be fast and easy.

Mine all flop. I've heard to plant deeply to help prevent flopping, but in my clay soil that's too much effort digging. I just use a twist tie and a stick and call it a day. I'm also wary of planting deeply as I have planted standard depths and have had planted unable to push out of my hard soil. I typically plant more shallow for that reason.