Aromatic annuals

Fragrance in the garden adds a layer of enjoyment throughout the growing season. While the appreciation of scent is subjective and personal, there are some amazing fragrances in our gardens that can stimulate our awareness and encourage us to breathe deep! Floral perfumes can lift our spirits and have long been associated with bringing back fond memories. Scientists have described several dozen emotional responses to floral scents in the garden and many gardeners are striving to include more substantial olfactory engagement with the selection and incorporation of specific plants in their gardens and landscapes.

Depending on where you live, certain scents may mark the time of year. In the Midwest, where I live, the fragrance of early-blooming woody plants such as lilacs (Syringa sp.), fragrant abelia (Abelia mosanensis) and Korean spice viburnum (Viburnum carlesii) certainly announce spring. My favorite summer fragrances include many perennial contributors like Oriental lilies (Lilium orientale) and garden phlox (Phlox paniculata), while the end of the season will include witch hazel (Hamamelis virginiana) and the cotton candy-like fragrance of katsura tree (Cercidiphyllum japonicum) foliage just as it hits maximum fall color and the leaves begin to drop.

Regardless of your location, you have access to a progression of seasonal fragrances that can be enjoyed out in the garden. And you can purposefully position plants for the maximum impact of ornamentation and smell! Fragrant annuals offer a lengthy contribution of scent over a wide growing range in the hotter summer months. They can also offer a more significant sensory dimension with a wide range of fragrance in terms of potency and timing.

Location, location, location Fragrance from plants in the garden is essentially offered in two “engagement formats.” First, there are flowers that emit a fragrance that drifts through the air to our noses. The other way to enjoy plant fragrance is through tactile engagement. Some plants need to be rubbed or brushed to release the “touchable fragrance” from the foliage. Many of our herbs (i.e., basil, rosemary, oregano) follow this pattern and need physical engagement.

It’s interesting to note that fragrance in plants is not a biological feature meant simply for human enjoyment. We are lucky to have these opportunities. Fragrance in flowers is typically related to pollination methods, with the primary goal of attracting the appropriate pollinators. Foliage fragrance is related to the chemical compounds within the leaf, with many of these chemicals acting protectively to minimize insect damage. Regardless, it’s important to understand how the scent is offered from your selections, as that will affect placement and use.

With the inclusion of scented plants in the garden, ask your customers to consider the placement of these plants in relation to the gardener. Consider the most traveled paths, sitting areas, decks and patios for targeted “scent pockets.” This is where fragrant annuals in containers, window boxes, beds and borders can contribute to the garden experience. A succession of smells might be a desired goal, although again, consider the peak timing of the scent, as that will likely be a factor in choosing a final location for your plants. In your garden center, place plants that emit fragrances throughout the landscape. Place “foliage engagement” scented plants along paths where visitors can brush against them as they move through the space. Also consider placing container plantings in close proximity to the deck and patio for exploration and engagement.

There is a wide range of scented annuals available on the market as either plant offerings or seeds. While many of these plants may be considered hardy in the warmest climates, their inclusion in this article is due to their ability to offer significant scent over a long period of time and their adaptability in a wide range of summer climates. Ken Druse, a famous horticulturist and author, encourages gardeners to accomplish a “fragrance inventory” and punch up the “scent quotient” in strategic spots. The following annuals are just a few ideas for consideration in your quest for more impactful garden fragrance.

Embed fragrance into the garden Do you like chocolate? Consider trying chocolate daisy (Berlandiera lyrata) for a constant succession of small yellow flowers offering the scent of chocolate. Technically a perennial for some, this native species is easy to grow as an annual and is quite heat- and drought-tolerant. The scent is enjoyed from close proximity as is the case with chocolate cosmos (Cosmos atrosanguineus). This native of Mexico is tuberous-rooted and will bloom throughout the summer with deep maroon daisies that smell like dark chocolate. The tuberous roots of chocolate cosmos can be dug and stored as you would cannas or dahlias for replanting the following spring.

If the scent of vanilla is of interest, consider the white heliotrope (Heliotropium arborescens ‘Alba’). The fragrance is quite enticing, and the sweet scent is also evident in many (but not all!) of the blue flowering selections. This native of Peru prefers a bit of pampering with decent soils and adequate moisture. The perfume of this plant is quite engaging and placement near the deck or patio is ideal. While excellent for a wide range of pollinators, heliotrope is poisonous (all parts) to humans and pets.

Flowering tobacco (Nicotiana sp.) has a long history of beauty in our gardens, with many selections offering a sweet scent, particularly at dusk. It’s important to mention that some flowering tobacco selections have no scent, so do your research to ensure that you get fragrant selections. The old-fashioned woodland tobacco (Nicotiana sylvestris) is a personal favorite for a strong aroma from the many dangling white flower trumpets at dusk. Tolerant of some shade, this selection can reach 5 to 6 feet in height. Reseeding may be an issue but consider cutting the plants back to the bottom set of leaves in mid-summer to encourage new stalks and a late flush of blooms (and less seed set!). The seven colors in the Perfume Series of hybrid Nicotiana offer reduced height, a broad color range and the same perfume in the early evening. With so many flowering tobacco selections out there, consider researching varieties that are a “slam dunk” for strong fragrance.

If the scent of popcorn is of interest, there has been a huge surge of interest in the “popcorn plant” (Cassia didymobotrya syn. Senna didymobotrya). Native to Africa, this legume produces beautiful clusters of yellow flowers throughout the summer. Used as an annual in more northern climates, it will reach large shrub size in one season. Rubbing the flower buds or foliage will produce the scent of buttered popcorn so this plant is certainly of interest to children of all ages! However, do note that this plant is poisonous.

Scent provided in the evening hours can be quite specific to a set of evening-blooming annuals that emit their perfume to attract nighttime pollinators. The classic moonflower vine (Ipomoea alba) is a favorite for opening in the evening and perfuming a vast area. If you are out in your garden in the evening as I am, an enticing scent as part of the experience is certainly appreciated. With the name devil’s trumpet, we should be wary of the poisonous qualities of Datura meteloides. Still, the white, trumpet-shaped blooms that unfurl in the evening offer an amazing fragrance. Also called jimsonweed, respect this plant for both its poisonous qualities and possible reseeding issues. However, there are a host of Datura varieties out there with different colors and double forms worthy of consideration.

The evening garden wouldn’t be complete without the sweet scent contribution of three more fragrant annuals. The evening-scented stocks (Matthiola longipetala ssp. bicornis), sown in spring, don’t look like much during the day, but in the evening, the small, “confetti-like” white and lavender release an intoxicating scent. This is an amazingly easy plant to grow as is the sweet four o’clock (Mirabilis longiflora). Sweet four o’clocks feature long-throated white flowers with a magenta center. A bit floppy at times, this plant is ideally planted among “supportive neighbors” where it offers the scent of orange. One of my favorite, fragrant evening bloomers to grow (and say!) is Zaluzianskya capensis. Night phlox, while diminutive in height (12 inches) and flower size ( ½ inch), packs an amazingly sweet punch in the evening. Closed during the day with the maroon underside of the petals forming a tight “fist,” night phlox pops open in the evening hours and is one of the most potent of the sweet evening bloomers.

While fragrance in the garden isn’t a new concept, it certainly can be augmented and maximized through the use of fragrant annuals to supplement the jaunty fragrances of your customers’ more permanent plantings. Proper consideration of growing conditions and positioning of these fragrant contributors is recommended, along with the encouragement to try some of the exciting additions to the home garden.