Their stems are generally unbranched, producing 1 to 9 narrow, sword-shaped, longitudinal grooved leaves, enclosed in a sheath.

The fragrant flower spikes are large and one-sided, with secun, bisexual flowers, each subtended by 2 leathery, green bracts. The sepals and the petals are almost identical in appearance, and are termed tepals. They are united at their base into a tube-shaped structure. The dorsal tepal is the largest, arching over the three stamens. The outer three tepals are narrower. The perianth is funnel-shaped, with the stamens attached to its base. The style has three filiform, spoon-shaped branches, each expanding towards the apex.

The ovary is 3-locular with oblong or globose capsules, containing many, winged brown, longitudinally dehiscent seeds.

These flowers are variously coloured, pink to reddish or light purple with white, contrasting markings, or white to cream or orange to red.

Gladioli are used as food plants by the larvae of some Lepidoptera species including Large Yellow Underwing.

Gladioli make very good cut flowers. However, due to their height, the cultivated forms frequently tend to fall over in the wind if left on the plant.