Insert a stake 6 inches into the ground behind each gladiolus corm at planting. Use a stake that equals the expected mature height of the gladiolus, which varies between 2 and 5 feet depending on the variety.
Tie the stem to the stake once the flower stalk is between 8 and 12 inches tall. Loop the tie around the stem and cross the ends before wrapping it around the stake and tying. Crossing the ends forms a figure-eight from the tie and the crossed tie cushions the stem so it doesn't rub against the stake.
Tie the gladiolus stem a second time once the flower buds begin to swell and open, indicating the stalk has reached its full height. Attach the plant tie in a figure-eight directly below the bottom flower bud.
Install a stake at either end of the gladiolus row. For long rows, space stakes between every three to four plants.
Attach a length of garden twine to the first stake once the flower stalks have reached half their expected height. Stretch the twine to the stake at the other end of the row, looping it around any additional stakes between the two on the end.
Tie a second length of twine to the first stake. Stretch it to the end stake on the opposite side of the gladiolus flowers, tying it in place. The two lengths of twine hold the gladiolus flowers upright between their lengths. Tall gladiolus varieties may require a second series of twine further up the stakes for full support.