Based on research conducted by Dr. Bill Miller of the Department of Horticulture at Cornell University, adding booze to the water used to force paperwhites (Narcissus tazetta) stunts their growth helping to prevent that awkward blossom flop that often occurs when the plants are forced indoors in winter.
The study prompted an inquiry from New York Times garden writer Leslie Land. One of her readers heard somewhere that pouring a little gin onto the paperwhites growing on pebbles in water would keep them from falling over, Miller explained.
Because he works with commercial growers who also find flopping to be a problem, Miller decided to give it a shot and scientifically research the premise. And they found that growing paperwhites in a 4 to 6 percent solution of alcohol is indeed an excellent way to regulate the plants growth and prevent flopping. You’d think it would make it worse. But when grown in water laced with 5 percent alcohol, plants reach only about a half to 2/3rds the height of those grown in plain water. However, the booze blasted blossoms were equal in size and lasted the same length of time as those grown in just water. Given that most liquors are 80 proof or 40 percent alcohol, a ratio is 1 part booze to 7 parts water will give you a 5 percent solution.
The directions are simple. Begin growing the bulbs in plain water for about a week to give the roots a chance to grow and the bulb to form a one to two inch green shoot. Then pour off the water and replace it with a 5 percent solution of any straight distilled spirits – gin, vodka, whiskey, scotch, rum or tequila will work. Beer, wine and flavored booze won’t do. The sugar content will damage the bulb. And don’t be tempted to dump in more booze. A solution of ten percent alcohol will injure the bulb and a 25 percent solution will kill it. So the researchers recommend staying with the 4 to 6 percent range for optimum performance.
Folks who don’t drink can substitute rubbing alcohol (isopropyl alcohol), which works just a well. It contains 70 percent alcohol so use the dilution ratio of one part rubbing alcohol to 10 parts water
It should be noted that rubbing alcohol is toxic to humans and should never be ingested so don’t try and drink this stuff.
What causes the alcohol to inhibit the plant growth? Dr. Miller suggests the answer is “water stress.” The alcohol makes it a bit more difficult for the plant to take up water and this slight reduction is enough to reduce both leaf and stem growth.
Will this method of regulating growth work on other forcing bulbs, such as hyacinth or amaryllis? I don’t know and the researchers didn’t say so try it at your own risk.