It depends on where you live. In California we don't dig up our Gladiolas. We wait until they are brown(they store nutrients for next year) then cut them to the ground. They come back every year. If you live where it snows, you might need to dig them up after they've died back. Taking note to remember exactly where they are planted.
Good luck.|||cut back and dig up and clean and let dry before frost and save in clean dry paper bag in basement or in cool but not cold place|||if its perrinial and comes from bulbs then cut down to about 3 inches and then mulch in the winter with dead leaves to keep the frost out of the bulbs and to save them|||The bulbs need to be dug up... you can try to cut them back and cover them with leaves or straw before it freezes but you may risk killing the bulbs and having to start over again in the spring.