In his latest book, Ken Druse candidly admits to a particular botanical bias. “When I come across a beautiful flower,” he writes, “the first thing I do (after checking for a bumblebee) is lean in to sample its smell.”
And if there’s no scent? “I find the blossom somewhat lacking.”
Mr. Druse is the author of 20 garden books including, most recently, “The Scentual Garden: Exploring the World of Botanical Fragrance,” which was awarded the American Horticultural Society’s top honor in March. He challenges those with gardens large and small — or even just a collection of houseplants or herbs in pots — to do a fragrance inventory and then punch up the scent quotient in strategic spots, taking into account multiple seasons and various times of day.
Scent is what Mr. Druse calls “the invisible garden,” a design layer often overlooked while we’re distracted by shopping for something in a particular color, or searching out a plant with a particular shape, scale or purpose. But factoring in fragrance delivers another sensory dimension.
No two noses are exactly alike, so the scents that you favor, from floral-sweet to herbal, fruity or spicy, are highly personal — and open to extremes of interpretation that Mr. Druse calls “the nose of the beholder.”
He has a bit of a party trick for visitors to his northwestern New Jersey garden: He asks them to describe a particular plant’s scent. With a minority of fragrant things, there is no dispute. Lemon verbena, chocolate cosmos and pineapple sage all resemble their well-chosen common names. But Calycanthus floridus, a shrub he loves that is native from Virginia to Florida, but hardy much farther north?
“What do you think it smells like?” he asks visitors to his garden between late May and mid-to-late June, as they sample the dark red blooms near his Carolina sweetshrub. Guests have offered a wide range of answers — bubble gum, strawberries, paint thinner. (Mr. Druse thinks it’s more like the inside of a whiskey barrel.) A green-flowered variety called Athens smells like Granny Smith apples or cantaloupe, depending on the age of the blossoms.
Party tricks aside, he offered some guidance on creating a more fragrant garden, indoors and out.
Focus on the Most-Traveled Paths
Add fragrance to places where you can sample it as you walk by — between your front door and driveway, for example. That should be obvious, but too often we forget.
It doesn’t need to be flowers, either, Mr. Druse said, recalling a low-growing “hedge” of hardy, upright rosemary leaning over the edge of a brick path on a university campus on Long Island. “Imagine brushing up against the evergreen herb as you walk by, and filling the air with its bracing scent,” he said.
Plan for a succession of smells. Don’t line the whole walk with lilacs, yielding a single scent-filled moment, but instead plant a staggered palette that mixes shrubs, down to perennials, bulbs and annuals.
“I have dwarf late-winter viburnums with their clove-scented flowers in March and April,” Mr. Druse said. “Then fragrant peonies and bearded iris. Next come the roses. In summer, the rich aroma of regal lilies intensifies in the evening.”
The lilies lean toward the light, he noted, so plant them on the darker side of the path. The same holds for daylilies (Hemerocallis), whose flared flowers Mr. Druse describes as having “a sweet and lightly fruity or citrus scent.”
There can also be fragrance underfoot, with creeping thymes in a sunny, well-drained place.
“I’ve grown Corsican mint, one of my favorite plants, with varying success,” said Mr. Druse of the half-inch-tall creeper he has managed to keep alive for a couple of years between the paving stones in moisture-retentive soil. “But I haven’t completely cracked the code. When it works and I step on it, the strong smell of peppermint drifts up to my nose.”
Up the Scent Quotient Near Outdoor Seating
The pathway advice holds true for plantings adjacent to patios, decks and other daytime seating areas: Extend the season. Many of the same plants work there. Other recommendations for sunny areas include spring-blooming mock orange (Philadelphus coronarius and Philadelphus x virginalis) and summer-blooming tall garden phlox (Phlox paniculata).
In shade, he suggested, one possibility is Hosta plantaginea. All hostas were once called plantain lilies with that white-flowered species in mind, and hybrids descended from it are typically scented.
Try Night-Scented Plants
If you sit outside in the evening, night-scented plants offer a way to connect with the garden through a sense of smell after dark.
Many of the most fragrant plants bloom at night, leading the early 20th-century garden writer Louise Beebe Wilder to call them “the vesper flowers.” They do it to attract night-flying pollinators like moths or even bats.
Admittedly, some — including tender plants like night-blooming jasmine (Cestrum nocturnum), old-fashioned trailing white-and-purple petunias (the heirloom variety Old-Fashioned Climbing is a good choice) and angel’s trumpet (Brugmansia) — do it so overpoweringly well that they may not be good candidates for placement close to a dining area.
“Capitalize instead on the gentler fragrances of moonflower, Nicotiana or evening primrose that would be perfect company on summer evenings, or just outside a screened porch,” Mr. Druse said.
Open the Windows
Bringing the outdoors inside is not just about creating views of the landscape, but letting in aromas, as well.
To enjoy spring’s lilacs from an upstairs bedroom, Mr. Druse said, select a cultivar that has some height: “Not a dwarf Korean lilac, but one like Syringa President Lincoln, long and leggy like its namesake, or the later-blooming Japanese tree lilac.” The latter, Syringa reticulata, has frothy, cream-colored June flowers with a honey scent; the former are Wedgwood blue.
Vines are another way to move fragrance upward, but they need trellises or stainless-steel cables to climb on.
Mr. Druse grows Clematis Betty Corning, which blooms for weeks, with bell-shaped blossoms “that smell like lavender flowers and are the same color,” he said.
Cold-hardy wisteria is also very fragrant, dominated by a honey aroma, “but as many gardeners know,” he said, “this plant is probably too powerfully aggressive for planting without a very sturdy trellis.”
In places with gentle winters, Zones 7 and warmer, Mr. Druse said, “true jasmines and their impostors would be obvious candidates.” Possibilities include winter jasmine (Jasminum polyanthum), star jasmine (Trachelospermum jasminoides, in Zone 8) and Carolina Jessamine (Gelsemium sempervirens).
Create a Patch of Touchable Fragrance
Many gardeners grow culinary herbs, some of which — the mints and rosemary, for instance — offer the extra delight of scent when brushed against. A group of pots positioned within reach, somewhere you pass many times a day, is an ideal way to incorporate such touch-me plants, even where there is no garden space.
Mr. Druse makes room, front and center, for some herbal-scented plants aren’t intended for the kitchen — like patchouli, anise hyssop (Agastache) and bee balm (Monarda).
The pelargoniums, or scented geraniums, were his gateway to fragrance. “Scented geraniums helped get me hooked on gardening as a teenager,” he said. As with many of his favorites, their leaves have to be rubbed to release the aromatic oils, which mimic sharp lemon, rose, peppermint, nutmeg and even coconut.
Some Native Plants Offer the Bonus of Scent
Besides being the best match for native pollinators and other beneficial insects, many native plants offer scent for the gardener to enjoy. A few Mr. Druse suggests considering: the scented foliage of mountain mint (Pycnanthemum); prairie dropseed grass (Sporobolus heterolepis), with late-summer and fall flowers that smell like popcorn or cilantro; and wintergreen (Gaultheria procumbens), whose foliage and fruits bear the scent.
The flowers of perennial black cohosh (Actaea racemosa) are honey-scented; milkweed’s are “thick and syrupy,” he said.
Some of his favorite native shrubs include that Calycanthus of his guessing game; Virginia sweetspire (Itea virginica), which smells like honey; fringetree (Chionanthus virginicus), with a scent of honey and vanilla; various deciduous azaleas (Rhododendron species); and moisture-loving summersweet (Clethra alnifolia), like clove with vanilla.
Choose Houseplants for Their Scent
In Mr. Druse’s New Jersey sunroom and throughout his house, a collection of tender houseplants emphasizes fragrance. Many of them migrate outdoors during the warmer months, where they sit in the gentle shade of a crab apple and dogwood.
“That’s where my hoyas in hanging baskets and Arabian jasmine, Jasminum sambac, spend the summer,” he said. But his potted lemons and limes, which bloom from February to June, “want more sun, so they vacation on the sunny edge of the shadows.”
Must-Have Fragrant Plants
Mr. Druse’s list is long: More than a hundred options for various climates are included in “The Scentual Garden.”
But if he was forced to pare down the list? “I couldn’t be without heliotrope, cottage pinks, licorice sweet flag, my beloved heirloom rose, lemon balm, tuberose and fruity cut freesias from the grocery,” he said.
Then he remembered one special treasure: “Who knew I could grow tropical allspice — Pimenta dioica — with its leathery, evergreen leaves that smell, well, like allspice in the house over winter?”
Fast Fragrance Facts
Fragrance in plants did not develop for our pleasure, of course, but as a form of defense against predation and to help attract pollinators, among other functions. The protective aspect is often packed into the foliar chemistry, telling an insect or animal that nibbles, “I’m not good to eat.” In the case of popular culinary herbs, like mints, oregano and rosemary, the same chemical compound that deters predators is what makes the plant taste good to us.
Fragrance is often evocative, and no wonder: Because of the brain’s anatomy, smell, memory and emotion are closely linked.
The best way to sample an aroma? Take short sniffs, not long, deep breaths. Then take an occasional break by smelling the crook of your elbow. “We’re accustomed to the scent of our own skin,” Mr. Druse said, “so it helps reset the nose to our baseline.”