I'm in zone 5 and my gladiolas just live on. Have had some for about 20+ years, and never dug them out.My step Dad had winning glad he would dig them each year then plant them in the spring each year if your in those zones
In colder zones, they may bite the dust like LG stated.

. Will try again when the farmer around the corner tills his field and plants. I've never used this seed before so if it doesn't go the next round will go back to native seeds for next year.