I imagine a balmy night, slight breeze, whiff of honeysuckle. A full moon rising. White plants overlooked in the daytime shine out in the darkness: dusty miller, sweet alyssum, night phlox.
And then there are flowers that only bloom at night: moon flower, four o'clocks, evening primrose.
Some plants are more fragrant in the evening: flowering tobacco, pinks, night gladiolus.
Or maybe it is that we, the tired gardeners, are more open to their scent.