As long as you've planted the bulbs at the right depth, and if they're out of the wind, they tend to remain upright anyway, though I usually have a single green cane on mine to stop the weight of the flower pulling it over. You can grow them in tubs, but a depth of 12 to 18 inches for the tub is important.

I use tomato [3lt] pots for mine. If I need to, I pop a cane in too, like bamboo.

thanks for the answers to my query on gladiolis - I'll give it a go this year.