Depending on the type of gladiolus bulb, most generally do well in zone 7. They thrive in well-drained soil. They should be planted 6-7 inches deep and 6-8 inches apart.
Gladioli should grow in Zone 7 as long as you wait until the soil has warmed up, probably in April. Plant them to at least the depth of the bulb and remember to lift them out of the ground at the end of the season.