I would strongly suggest that if you want to grow a gladiolus, you should plant it in a large pot because small pots don't provide enough room for the root system to expand and develop. Gladiolus needs lots of space. Also, they like a sunny spot that gets lots of light but isn't exposed to direct sunlight. If you plant your Gladiolus in soil that has been used for tomatoes, squash, cucumbers, or anything else, you're asking for trouble.