Most of the desert plants such as some Cactus, the species of Oenothera like the evening primrose, Cereus etc. bloom at night. A prominent factor is that the flowers of these desert plants get pollinated during night times.
The night-flying insects and moths help in the pollination, and thus to increase reproduction. Even these flowers don’t look colorful, as the amount of chlorophyll prepared will be less due to the scarcity of water. Hence they are mostly in white or pale color but these flowers are clever enough to attract the night-flying insects by radiating great smell, for which these insects get attracted and help in pollination.
As these plants need to conserve the less amount of water they get through short rains, the flowering activity also slows down. The night weather is suitable for these flowers to bloom as the temperature is low.