ITHACA, N.Y. – For home gardeners who don't want their flowers to tip over, a Cornell University horticulturist thinks he has the answer: Get the flowers a little tipsy with some hard liquor.
Giving some plants diluted alcohol — whiskey, vodka, gin or tequila — stunts the growth of a plant's leaves and stems but doesn't affect the blossoms, said William Miller, director of Cornell's Flower Bulb Research Program.
Miller reported his findings in the April issue of HortTechnology, a peer-reviewed journal of horticulture.
"I've heard of using alcohol for lots of things ... but never for dwarfing plants," said Charlie Nardozzi, a senior horticulturist with the National Gardening Association, a Vermont-based organization that promotes plant-based education.
"It sounded weird when I first heard about it, but our members say it works. I'm going to try it next year, just for curiosity," Nardozzi added.
Miller's study focused on paperwhite narcissus and other daffodils but he's also had promising results with tulips.
"I think with a little jiggering — no pun intended — the method will work for tulips, though I think it will not be as simple as with paperwhites," he said.
Miller began his investigation last year after receiving a call from The New York Times about a reader who had written to the garden editor claiming that gin had prevented some paperwhite narcissi from growing too tall and floppy and asked if it was because of some "essential oil" in the gin.
Intrigued that diluted alcohol might act as a growth retardant, Miller began conducting experiments with ethanol. Because hard liquor is easier for consumers to obtain, he switched to alcohol and began trying different kinds, including dry gin, unflavored vodka, whiskey, white rum, gold tequila, mint schnapps, red and white wine and pale lager beer, on paperwhites.
The beer and wine did not work, likely because of their sugar content, he said.
"While solutions greater than 10 percent alcohol were toxic, solutions between 4 and 6 percent alcohol stunted the paperwhites effectively," said Miller. "When the liquor is properly used, the paperwhites we tested were stunted by 30 to 50 percent, but their flowers were as large, fragrant and long-lasting as usual."
Any economic benefits, at least directly, are slight, he said. Commercial horticulturists already have other growth-control methods for large-scale production. But for home gardeners, the gain is in terms of product quality. According to the NGA, 83 percent of all U.S. households participate in some type of indoor or outdoor gardening activity.
Miller, however, said he could envision profitable marketing schemes emerging from the study.
"Maybe, instead of charging $1 for a bulb," he said, "you can market that $1 bulb with a mini bottle of Tanqueray, insert a little card with some history and instructions, put it in a fancy package and charge $10 for it."
Miller isn't sure why the alcohol stunts plant growth, but he has three theories that he is exploring.
— Growth is caused when plant cells absorb water and expand. The alcohol could be injuring the plant roots, preventing the roots from absorbing the water as efficiently.
— When alcohol is mixed with the water, the plant has to use more of its growing energy to extract the water from the solution.
— The plant uses its growing energy to rid itself of the alcohol it has absorbed.
Miller will be working this spring to see if a little booze works for amaryllis and such vegetables as tomatoes and peppers.
Imagine, he joked, you may be able to grow your own Bloody Mary.