The biggest group of Gladiolus, the large-flowering category are definitely the big brothers in the family, reaching up to 1.8 meters in height. Large-flowering gladioli, with their extremely long flower spikes filled with large tightly-packed blooms, make an impressive statement in any garden, and as cut flowers offer the chance for imposing floral arrangements. However, because of their height and the length of their spikes, it is often necessary to give them the back row in borders and to assist them with caning, so as to keep them up straight. Large-flowering gladiolus bulbs like plenty of water, but don’t like standing in it. Pick a sunny spot where the soil is well-drained.