Garden Myths Gardening Watering

Garden Myth: Plants Grow Better with Coca-Cola

Is watering plants with soft drinks really good for them? Source: & Montage:

No, Coca-Cola is not good for plants … and you can substitute the soft drink of your choice for Coca-Cola in that statement. Where this strange belief comes from, I have no idea, but it’s widely repeated on the Internet.

Soft drinks are essentially carbonated water with lots and lots of added sugar. Carbonated water in itself is not harmful to plants and could even be good for them under some circumstances, but that’s not the case for sugar or, should I say, sugars, as various kinds of them are used in soft drinks: glucose, fructose, sucrose, etc.

True enough, plants produce their own sugars and use them for their growth, but they can’t absorb them: the molecules are far too complex for roots to take in. And when you break down sugars, they give only products plants are already getting from air and rainwater: hydrogen, oxygen and carbon. So where’s the benefit?

Adding too much sugar to soil can lead to dehydration, as water will be pulled out of the plant’s roots to dilute any concentration of sugar (this is due to osmosis, something many of you probably vaguely remember from school). Plus the bacteria and fungi that break down sugars are not usually ones that are beneficial to plants in any way and may become so numerous they “gum up” the soil, preventing air and water circulation. Also, many sugar-loving soil microbes are actually harmful to plants, notably causing root rot.

So, watering plants with soft drinks does no particular good and can possibly harm them.

I suggest just watering plants with … water! It’s cheaper and better for them.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

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