Growing small gladiola in containers
What size pot to use and how deep to plant a single glad bulb in a small container for a senior gardening project?
Doug says the problem is that the glad is a very tall, top heavy flowering plant. You're going to require at the very least a 6-8 inch Azalea pot (one that's broad instead of deep) And you're going to have to make sure you anchor that pot somehow so when the weight of the bloom happens, the pot is held upright. You might want to use a clay pot as a starter just because it's so heavy itself.
Plant the bulb two times it's height. So if a bulb is one-inch tall, plant it two inches deep. You can go deeper with a glad - 3-4 inches.
Good luck