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A Fragrant Comeback
17 Feb, 2009 By: Janet Aird Get Growing Fragrant columbine (Aquilegia fragrans) is an evening-fragrant perennial with a sweet scent. |
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.
“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 five in the 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, like butterflies, hummingbirds and bees, tend to be less fragrant than the plants that attract nighttime ones, such as moths and bats.
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.
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), whose leaves smell like burnt rubber when they’re crushed, according to the website of Cornell University’s Department of Horticulture.
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 is pollinated by beetles or flies, they’ll be attracted to red trilliums, also known as stinking Benjamin (Trillium erectum), or durian, which smells like rotten meat.
Check out the March issue of Landscape Management for the full article, including fragrant cultivar suggestions and planting tips.
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