March 31, 2006

Why tipsy flowers don't tip over: Booze stunts stem and leaves, but doesn't affect blossoms, study finds

From left: Untreated paperwhites grown in water, plants grown in 2 percent, 4 percent, 6 percent, 8 percent and 10 percent ethanol.

Those paperwhites and other daffodils sure could use a drink -- a little whiskey, vodka, gin or tequila could keep them from falling over.

A new Cornell study finds that a touch of booze is a great way to keep certain houseplants from getting too tall by stunting their growth. "Dilute solutions of alcohol -- though not beer or wine -- are a simple and effective way to reduce stem and leaf growth," said William Miller, professor of horticulture and director of the Flower Bulb Research Program at Cornell.

"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," added Miller, whose new study on how alcohol inhibits houseplant growth will be published in the April issue of HortTechnology, a peer-reviewed journal of horticulture.

Miller will be working this spring to see if a little booze works for amaryllis and such vegetables as tomatoes and peppers, as well. His work with tulips so far has been promising but not yet definitive: "I think with a little jiggering -- no pun intended -- of the system, the method will work for tulips, though I think it will not be as simple as with paperwhites."

Last year, Miller received 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 dilute alcohol might act as a growth retardant, Miller and former Cornell student Erin Finan '05 conducted experiments with ethanol (1, 5, 10 and 25 percent) and "Ziva" paperwhite narcissi (Narcissus tazetta), and later with about a dozen kinds of alcohol, including dry gin, unflavored vodka, whiskey, white rum, gold tequila, mint schnapps, red and white wine and pale lager beer, on paperwhites.

"While solutions greater than 10 percent alcohol were toxic, solutions between 4 and 6 percent alcohol stunted the paperwhites effectively," said Miller.

To control stem and leaf growth, he suggests waiting until paperwhites or other daffodil shoots are several inches long to drain the water and replace it with a solution of 4 to 6 percent alcohol -- hard liquor or rubbing alcohol.

To get a 5 percent solution from 80-proof liquor, which is 40 percent alcohol (such as gin, vodka, whiskey, rum or tequila), add one part liquor to seven parts water. To use rubbing alcohol (isopropyl alcohol), which is 70 percent alcohol, dilute one part with 10-11 parts water.

Why does booze stunt plant growth? "We don't know, but we're working on this," Miller writes in a fact sheet available on the Web called "Pickling Your Paperwhites" (available at

"We think it simply might be water stress, that is, the alcohol makes it more difficult for the plant to absorb water, so the plant suffers a slight lack of water, enough to reduce leaf and stem growth, but not enough to affect flower size or flower longevity."

But don't serve beer or wine to plants -- the sugars wreak havoc on their health.