The Scentual Garden: Exploring the World of Botanical Fragrance

[The Scentual Garden] cover

“Green, resinous, camphorous, nutmeg, a scant suggestion of lemon rind.” Ken Druse has a very keen nose. In The Scentual Garden, he undertakes an adventure, as he puts it, to classify botanical fragrance. Druse wants to give gardeners and designers an expanded lexicon for scent that equals the rich vocabulary we already have for color, texture and form. It won’t surprise anyone familiar with his other books that The Scentual Garden is ‘coffee table’ quality, with heavy paper, lots of color photographs of plants in the landscape and of composed portraits of plants on a solid color background. It’s pleasurable to simply flip through the pages for Ellen Hoverkamp’s photography alone. However, once you start reading the text of this reference book you will ask yourself, do I get “nutmeg and a scant suggestion of lemon rind” from my rosemary shrub?

Druse devised 12 “botanical fragrance categories.” Most are obvious and self-explanatory, such as fruity, medicinal, spice and forest. Others are more esoteric and mysterious, like heavy or indolic, which is described as “mothballs, hot garbage, overripe fruit, excrement…” Eww! Apparently some pleasant-smelling flowers, like gardenia, can have a secondary background scent of indole. I say “apparently” because when I smelled my own gardenia in flower just now I didn’t get anything indolic. But smell is deeply personal, as Druse fully explains in the opening chapters. I grew two varieties of heliotrope this past summer. One smelled like delicious vanilla/cherry pie as expected while the other smelled like the horrible synthetic fragrance used to clean public restrooms. My husband thought of urinal cake. I’ll not grow that cultivar again!

Each category includes an explanation with sample plants, followed by encyclopedia entries for more plants in the category. Plant entries describe the scent, use in the garden, cultivation tips, sometimes a bit of history, and sometimes recommended cultivars. Druse writes with honesty and insight, from personal experience of decades of knowing plants. After reading The Scentual Garden, I’m more likely to sniff my plants and ponder in which category they belong and whether there is a hint of indole in my star jasmine.

Published in the November 2020 Leaflet, Volume 7, Issue 11.

Fragrant daylilies

I’ve planted all sorts of daylilies that are supposed to be fragrant, but to my nose, the fragrance is barely detectable. Is there a trick to getting a fragrant daylily?

Fragrance can be a matter of some subjectivity, and it may also vary with different times of day and site conditions. Have you tried planting any of the varieties which have won the L. Ernest Plouf Consistently Fragrant Hemerocallis Award? The name of the award itself suggest that consistency of fragrance is an issue. A co-owner of B & D Lilies in Port Townsend, WA says that getting enough heat is the primary factor in producing a noticeable fragrance from your Hemerocallis.

loss of fragrance in roses

I wonder why my roses have lost their fragrance. My ‘Double Delight’ roses used to have a good smell, and now the flowers are bigger and there is no fragrance.

It does seem mysterious that a once-fragrant rose should lose all fragrance. There are many factors which might cause the perceived lack of scent. According to The Graham Stuart Thomas Rose Book (Timber Press, 1994), rose scent itself is complex, and is composed mainly of geraniol along with many other substances. It is mainly released from tiny cells on the surface of the petals: “Scent is produced mainly in the petals and is given forth when the growth of the flower and the atmospheric conditions are right. From this it will be seen why double roses have more volume of scent than singles […] scent is especially apparent in most flowers when the air is neither too cold nor too hot […] In extreme conditions, such as wilting, extra scent may be released […] Usually the best fragrance is obtained from a newly opened flower growing on a healthy, well-established plant on a windless day when growth is exuberant […] we may expect fragrance to be at its best on a day when the air is warm and moist rather than dry, when the plant will be functioning well. It is not that moist air conveys better than dry, but that the plant is giving it forth in greatest quantity.”

From the above, you may want to consider the following

When you discovered the rose had no scent, were the atmospheric conditions optimal for the release of scent?
If scent is most prominent on healthy plants, are there any underlying reasons (pests, diseases, cultural problems such as overwatering, poor soil, etc.) the plant might not be at its strongest?

Other things to consider:
Environmental pollutants affect not only our sense of smell, but the fragrance emitted by flowers, as this 2008 University of Virginia study describes:
“‘The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today’s polluted environment downwind of major cities, they may travel only 200 to 300 meters,’ said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study. ‘This makes it increasingly difficult for pollinators to locate the flowers.’

The result, potentially, is a vicious cycle where pollinators struggle to find enough food to sustain their populations, and populations of flowering plants, in turn, do not get pollinated sufficiently to proliferate and diversify.”

Another thing that you might ask is whether your rose was grafted, and perhaps you are getting a different rose coming up from the graft. The loss of fragrance and the different appearance of the flowers makes me wonder if this could be what is happening.

fragrance in Hamamelis

I visited the Washington Park Arboretum in January and admired the blooming Hamamelis. There was strong fragrance in the air, but we were unable to tell which tree was the most fragrant. Can you tell me which variety is most fragrant of the ones in the Arboretum?

Also, I have read that Hamamelis virginiana is very fragrant but I don’t know if it does well here in the Northwest.

Scent can be a subjective matter, but the local group Great Plant Picks does have an evaluation of various Hamamelis species and cultivars, and according to their list, Hamamelis mollis is exceptionally fragrant compared to the rest.

Missouri Botanical Garden agrees with this assessment, stating that Chinese witch hazel (H. mollis and its cultivars) is the most fragrant species.

About the scent of Hamamelis virginiana, Chris Lane’s book Witch Hazels (Timber Press, 2005) only says “sweet scent.” In his book, Winter-flowering Shrubs, Michael Buffin rates the scent of various witch hazels as follows:

H. mollis: highly scented
H. x intermedia: varies; ‘Pallida’ has most scent; ‘Aphrodite’ slightly scented; ‘Allgold’ is strong but slightly musky; ‘Arnold Promise’ has strong scent; ‘Barmstedt Gold’ is very slightly scented; ‘Dishi’ is highly scented; ‘Diane’ nearly scentless; ‘Hiltingbury’ weakly scented; ‘Jelena’ moderate; ‘Moonlight’ strong, sweet; ‘Orange Peel’ reasonably good scent; ‘Sunburst’ lacks scent; ‘Vesna’ very sweet; ‘Westerdale’ moderate; ‘Winter Beauty’ scentless.
H. japonica: sweet but faint
H. vernalis: musky
H. virginiana: slightly scented

Hamamelis virginiana is more commonly grown for providing astringent, or as commercial rootstock than as a garden plant. It is native to eastern North America, though it will also grow here in the Northwest. It has a habit of holding onto its dead leaves.

Here is another article which discusses fragrance in Hamamelis, from Swarthmore College’s Scott Arboretum blog (posted 2/25/2011). the author says: “Getting my top ranking was H. mollis ‘Wisley Supreme’ and ‘Early Bright’ which do hold some leaves but have fantastic fragrance.”

As an example of the subjectivity of smell, see the following from Val Easton’s Seattle Times column:
“Q: I have purchased a Hamamelis virginiana and I don’t think it is anything like (the fragrant plant) you have written about. Will you let me know exactly which witch hazel has great fragrance and blooms in January/February?
A: The liniment witch hazel is made from the bark of Hamamelis virginiana, but that’s your plant’s main claim to fame. The Chinese witch hazels (Hamamelis mollis), and plants crossed with them, are supremely fragrant and bloom in winter (H. virginiana blooms in autumn and its flowers are so small they’re often lost beneath the leaves). Some of the earliest-blooming witch hazels are Hamamelis x intermedia, which have the Chinese witch hazels as one of their parents; ‘Pallida’ blooms earliest in late January or February; ‘Diane’ has dark red flowers, and ‘Arnold’s Promise’ has large, bright yellow flowers a little later in the winter. All are deliciously fragrant.”

The Fragrant Path: a Book About Sweet Scented Flowers and Leaves

One of my favorite books on fragrance is The Fragrant Path by Louise Beebe Wilder. Published in 1932, and re-issued in 1990 (the Miller Library has both editions), I don’t think there is a garden fragrance book today that’s any better.

Why? No other author is as skilled a writer, nor as comprehensive on this topic. Wilder was both an avid gardener and a thorough researcher, and she was skilled at blending book knowledge, quotes from writers past, and hands on (or is it nose on?) experience into her writing. She was also a good story teller, making her books (I recommend them all) read more like a memoir than a gardening guide.

There are no photos in this book. They’re really not necessary. Scent is difficult enough to define without distractions for your other senses, but Beebe is quite successful at describing its elusive qualities. For example, when at a garden party with a witch hazel in full bloom, she notes “The fantastic little tree was sending us messages, remaining quiet for a time and then again seeking to get in touch with us.”

She was incredibly thorough. There are whole chapters on all the popular choices including roses, scented geraniums, and gilliflowers (carnations and their kin). More remarkable are the chapters on scented flowers of the rock garden, scents found in the berry patch or orchard, and, my favorite, “Plants of Evil Odour.”

The fragrance of honey fills another chapter. My mouth waters reading about “rich dark Buckwheat honey” or “delicious amber-hued and very fragrant honey [that] is produced where the bees feed upon the Orange blossoms.”

Most amazing is the chapter on “Wild Scents.” For one who gardened near New York City, she is surprisingly inclusive of the West Coast native flora, describing the sweet qualities of Trillium ovatum, Myrica californica, and Cornus nuttallii amongst others.

She also considers tender trees and shrubs. We are lucky as many of these selections, available to her only as conservatory plants, will survive and spread their perfume in our marine climate!

Published in Garden Notes: Northwest Horticultural Society, Spring 2014