Fragrant Native Plants

Flower scent is a signal aimed at somebody

Fragrance costs a plant energy, so it is produced when the intended visitor is active and not otherwise.

Sweet scent that strengthens at dusk is aimed at night-flying moths. Woodland phlox does this, and its evening fragrance is much stronger than its afternoon one. Plants pollinated by day-flying insects are usually strongest in warm midday sun instead: swamp milkweed and Joe-Pye weed both carry vanilla notes that peak in afternoon heat.

Some scents are aimed at nobody you would expect. Prairie dropseed's flowers smell of coriander and buttered popcorn, unmistakable on an August evening from several feet away, and the plant is wind pollinated, so the scent is a curiosity rather than a signal.

And a few are timed oddly. Chocolate flower genuinely smells of cocoa, strongest in the cool of early morning and gone by midday, which means most people never encounter it.

Foliage scent is defense

The plants whose leaves smell strongly when crushed are almost all producing volatile oils to make themselves unpalatable, and that is exactly why they turn up on deer-resistant lists.

Mountain mint smells of spearmint. Anise hyssop smells of licorice. Wild bergamot and beebalm smell of oregano and thyme. Yarrow is sharply herbal. Aromatic aster smells of balsam. Spicebush is citrus. Fragrant sumac is a sharp herbal note.

None of these release scent on their own. You have to brush them or crush a leaf, which changes where they should go.

Site scent where people are

This is the practical conclusion, and it is the one most often missed.

Fragrance from foliage requires contact, so those plants belong at the edge of a path where a leg brushes them, beside a bench, or at the corner where people turn. Planted at the back of a border they may as well not be fragrant at all.

Flower fragrance carries a short distance in still air and further on a warm evening, so those plants belong near a door, under a window that opens, or around a place people sit after dark.

Enclosure helps. Scent pools in a courtyard, along a fence, or in a sheltered corner, and disperses in an open windy yard.

Two cautions

Fragrance is not evenly distributed among cultivars. Selections bred for flower size or color have in some cases lost scent, so buy fragrant plants in bloom where possible and check.

And strongly aromatic foliage can irritate skin for some people, and several of these plants are ones to handle with gloves rather than to taste. Growing them for scent does not make them edible.

Sources: Lady Bird Johnson Wildflower Center, University of Texas at Austin (species profiles and fragrance notes); Xerces Society (moth pollination and night-scented flowers); Mt. Cuba Center (trial observations on cultivar characteristics).