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A fragrant comeback
1 Mar, 2009 By: Janet Aird LivescapesGet your clients to stop and smell the roses, and the jasmine, lilacs, mint, viburnums and more.
We're used to smelling roses, jasmine and mint in gardens, but chocolate? Licorice? Cinnamon? There are a surprising number of fragrances and fragrant plants, and homeowners are beginning to rediscover them.
 Freesia |
"These days fragrance is coming back," says Marita Tewes Tyrolt, horticultural director at the University of Utah's Red Butte Garden, which has a fragrance garden of about half an acre. It has about five types of fragrant trees, 30 shrubs and sub-shrubs, including herbs, and close to 40 perennials. They add annuals for seasonal displays, usually about five in spring/early summer and 10 to 12 in summer/fall.
There are two types of fragrant plants, she says. Some, like lilacs, roses and freesias produce essential oils on their petals to lure pollinators. They're called "free" because they give their scent freely. The ones that attract daytime pollinators, such as butterflies, hummingbirds and bees, tend to be less fragrant than the plants that attract nighttime ones, like moths and bats.
 Marigolds |
Other plants, such as marigolds and herbs, produce essential oils on their leaves, stems, seeds or bark, often to repel leaf-eating predators. They're called "fast," because they release their fragrances when the oils are rubbed, bruised or crushed.
"Each plant produces a constant amount of essential oil," says Fritz Kollmann, a horticulturalist and crew leader at the fragrance garden, but the intensity of the fragrance can vary according to the time of day, humidity and heat. Flowers that open in the evening tend to have the strongest fragrance in the evening. Different essential oils oxidize at different temperatures. And some scents tend to hang in the air when the humidity is higher.
 The University of Utah's Red Butte Garden has a fragrance garden of about half an acre. |
You have to be careful about cultivars, Tewes Tyrolt says. Some are intoxicatingly fragrant and others have no fragrance at all. In many of the newer ones, fragrance has been sacrificed for other attributes, such as size and color of the blooms, hardiness and resistance to pests.
And don't assume that fragrance is always an asset.
"Fragrant means that a plant has an odor," she says. Some, like roses, are pleasant to everyone. Some have one cultivar with a pleasant fragrance, such as the wayfaringtree (Viburnum lantana), and another with a distinctly unpleasant one, such as Siebold Viburnum (Viburnum sieboldii), which has leaves that smell like burnt rubber when they're crushed, according to the website of Cornell University's Department of Horticulture.
 Lilacs Syringa Inflorescence |
Then there's the stink tree (Ailanthus altissima). More commonly called the tree of heaven, its flowers and twigs emit a smell that some have compared to cat urine.
"You have to think what is pollinating the flowers," Tewes Tyrolt says. If it's beetles or flies, they'll be attracted to red trilliums, also known as stinking Benjamin (Trillium erectum), or durian, which smell like rotten meat.
 Peony |
Fragrant flowers
The same plants can be trees in one part of the country and large shrubs in another, shrubs in one part and perennials in another, or perennials in one part and annuals in another. The Latin name is included below when there may be some confusion about the names and when one cultivar is especially fragrant.
"Many trees are fragrant in the spring," Tewes Tyrolt says. "The littleleaf linden (Tilia cordata) has flowers that smell like chocolate to some people."
 Aquilegia Fragrans |
One of Kollmann's favorites, the mimosa tree (Albizia julibrissin 'Rosea') "creates an incredible effect," he says. "They bloom for two and a half months. The flowers tickle your nose."
Other trees with fragrant flowers include the black locust (Robinia pseudoacia), sweet tea olive (Osmanthus fragrans) and magnolias. Fragrant shrubs include witchhazel (Hamamelis), lilacs (Syringa), two different shrubs called mock orange (Philadelphus and Pittosporum), roses and viburnums.
 Wisteria |
"We have a heavy focus on perennials," Tewes Tyrolt says. Some of the most fragrant are peonies, lily of the valley, sweet William and carnations (both Dianthus), hostas, heliotrope and the vine, clematis. Some fragrant annuals are hyssop (Agastache), sweet alyssum (Lobularia maritima), pansies and violets (both Viola), and stocks (Matthiola), and the vines, nasturtium (Tropaeolum), sweet pea (Lathyrus odoratus) and corkscrew vine (Vigna caracalla). Bulbs with fragrant flowers include irises, hyacinths and freesias.
Flowers that open in the evening tend to have the most intense fragrance. "A new evening primrose (Oenothera fremontii 'Shimmer') is just incredible," Kollmann says. "It has thin silver leaves, an amazing subtle fragrance and a carpet of yellow flowers that blooms all summer."
 Orchid |
Other evening-fragrant perennials include orchids (Cestrum nocturnum), Oriental lilies (Lilium), fragrant columbine (Aquilegia fragrans) and four-o'clocks (Mirabilis jalapa). Annuals include flowering tobacco (Nicotiana) and night-scented stocks (Matthiola), and shrubs, daphne, gardenias, night-blooming jessamine (Cestrum nocturnum) and frangipani (Plumaria). Tuberose (Polianthes tuberosa) is a fragrant bulb.
Wisteria vines are a major element of the fragrance garden, Kollmann says. Other evening-fragrant vines include honeysuckles (Lonicera), jasmine, star jasmine (Trachelospermum jasminoides) and moonflower vine (Ipomoea alba).
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