The flowers of Gladiolus patersoniae grow in an inclined, two- to five-flowered spike. The floral bracts are grey-green with purple often added. The margins appear glassy. The outer bract is larger, enveloping the inner; the tips of both pointed.
The inflated flower has an oblique, broad-based perianth tube, the tepals unequal. It is almost bell-shaped, two-lipped and nodding. Flower colour in picture is pale blue and white with darker blue-mauve inside. Purple and yellow markings on the lower tepals are fairly variable. The dorsal tepal is hooded, angled so that its often intense inner colouring remains unseen.
In the easterly parts of the plants distribution the flowers may be pale yellow, while pinkish purple and almost white forms also occur. The corolla is about 3 cm in diameter.
The stamens are included under the dorsal tepal, the anthers and pollen whitish. The flowers are pollinated by long-tongued bees that find a little nectar in the tube.
Flowering occurs from late winter to spring, earlier at lower elevations (Goldblatt and Manning, 1998; Vlok and Schutte-Vlok, 2010; Manning, 2009).