Answer: Generally, it's good to mix annuals and perennials, since annuals blossom all season long if deadheaded regularly, and perennials tend to have a shorter period of time when they are in peak bloom. Since many night-flowering plants are very fragrant when evening sets in, plant them where you are most likely to catch their scent, such as under a window, or next to a garden bench or walkway.
Some evening bloomers include: moonflower vine, night blooming jasmine, evening primrose, nicotiana, and night phlox. Some lovely perennial choices for you include: Phlox paniculata 'David' or Mt. Fuji', Echinacea purpurea 'White Lustre' or 'White Swan', delphinium 'Galahad', tulips, daffodils, hyacinth, iris, liatris, Achillea 'Snowsport', candytuft "Snowflake', lilium 'Snow Trumpet', Monarda didyma 'Snow White', Queen Anne's Lace, astilbe, Shasta daisy, white Thalictrum (meadow rue), and Veronica speedwell 'Alba'. Some rugosa roses have white flowers.
Annuals include: Moonshadow sunflower, white impatiens, French Vanilla Marigold, alyssum, White Sonata cosmos, Misty White nigella, Pearly Gates morning glory, German statice, helichrysum, white geranium.
Good luck and have fun designing your white garden. I hope it's near the house so you can appreciate its nighttime glow more easily.
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