The nose knows a rose

Thanks to rose breeding in the 20th century, we can have a rose of any petal color except true blue. We can gaze upon large blooms of 100 petals. We can even find the right type of rose bush to plant almost anywhere and it will flourish.

An unintended consequence of chasing beauty and hardiness in roses has been that some of them have lost their intoxicating scent. Historically, all English roses had an odor. Unfortunately, cross breeding with the China Rose and the Tea Hybrid Rose in the 19th century resulted in passing on their lack of scent along with desired characteristics like large bloom size.

Today, several prominent rose breeders are on a mission to rescue roses from this identity crisis. For a rose’s mysterious allure lies in its scent. Just ask any poet.

So what went wrong? Only recently did Magnard et al (2015) discover how roses get their scent, detailing the complex process in the Science journal article “Plant Volatiles: Biosynthesis of Monoterpene Scent Compounds in Roses.” To summarize, roses’ scents are due to monoterpenes, naturally occurring chemicals found in all kinds of odorous plants.  While their molecular structure can vary greatly, lending themselves to unique scents, all contain ten carbon atoms.

They don’t produce scent on their own though. Enzymes are needed to “snip” them in order to produce an odor. Magnard et al (2015) found unscented roses to be missing the snipping enzyme RhNUDX1. It is required to do one of the two snips required to make a monoterpene molecule smelly.

Many of us may not have smelled the full sweet scent of a rose. Most supermarket and florist blooms are bred for shipping from overseas and have lost their scent. While the scent being bred out of roses was unintentional, it did not go unnoticed.

Want to get your hands on intoxicatingly scented roses? Some garden roses have retained their scent and several breeders have successfully produced new scented varieties in recent years, perhaps most notably, David Austin. You’ll have to plant your own though, as bouquet roses usually do not smell very strongly at all. You can also contact your local rose society or garden club to find out where you may be able to visit an old rose bush. Those of you in Portland, Oregon are especially lucky!

Photograph in the Carol M. Highsmith Archive, Library of Congress, Prints and Photographs Division. Creative planting at the International Rose Test Garden in Portland, Oregon’s, Washington Park. Blossoms on the garden’s more than 10,000 rose bushes (of approximately 650 varieties) bloom from April through October. The garden is the oldest continuously operating public rose test garden in the United States and exemplifies Portland’s nickname, “City of Roses.”

For gardeners proven and aspiring alike, I recommend purchasing bare root roses directly from David Austin Roses. They will arrive at the right time of year for planting in your zone. Check out this page featuring their most fragrant English roses. I do not get anything for this shout out, and in fact have chosen to forgo affiliate opportunities that would cost you more than buying direct.

Happy planting & smelling fragrant roses!