Moonflowers, the ones that resemble datura, which open at night. You can actually watch them unfold. There’s also a moonflower vine that is like a white morning glory.

Evening primrose is another suggestion. Brunnera macrophylla has pure blue flowers that seem to glow at dusk. So do lavender flowers.

blue delphinium
blue bellflower
white impatiens

I am assuming that since you refer to a moon-themed garden, you will be visiting it in the night. White flowers are always a good bet. Asiatic Lilies, Annual Alyssum, Lavender, and Daturas all come in white hybrids which are fragrant at night. White varieties of Dianthus Plumarius, the cottage pink, can be selected for scent in both single and double-flowered forms for edging borders.

I would definitely put in quantities of Nicotiana Alata, the flowering Tobacco. The true species grows to five feet tall and is powerfully fragrant at night and glows ghostlike in the dark.

Petunias are a gaudy and rather sour lot during the day, but white varieties are usually dependably and pleasantly perfumed in the night hours.

Matthiola Bicornis, the Evening Stock, is very easily sown in situ for luxuriant scent all night long. The ordinary sorts of stocks are spicily clove-scented.

In late spring and early summer, large groupings of Hesperis Matronalis, the Sweet or Dame’s Rocket will be intensely fragrant after midnight.

Some types of Honeysuckle (Lonicera) reserve their far-reaching perfumes for nighttime only. And don’t forget Magnolia Grandiflora, the evergreen Magnolia, which blooms off and on throughout the summer with huge scented waxen white goblets. It’s always worth a shot to put in a Gardenia, too.

Hylocereus, the night-blooming Cereus, is a houseplant that may be hung or its pot perched on a pedestal throughout the summer months. Huge white fragrant flowers opening in the wee hours are cause for a middle-of-the-night get together for friends to watch and marvel.