Can Beer Make Plants Grow?

Madeline Wajda
Adams County Master Gardener

I have just discovered a book, The Truth About Garden Remedies, that I found very useful and enlightening and would like to recommend to anyone trying to save money while tending their garden. The book is written by Jeff Gillman, Ph. D., an associate professor in the Dept. of Horticultural Science at the University of Minnesota, and published by Timber Press, Portland, Oregon, 2006. The book is divided into four main sections: fertilizers, water, biostimulants (which cover a number of non-fertilizers thought to affect the growth of plants-including talking to your plants), and pesticides and protectants. Within each section, there are entries for various products and remedies. After a brief introduction of each remedy or product, there is a description of practice, the theory behind it, the "real story," and finally what it means to the home gardener-complete with a one- to five-flower rating system (except for talking to your plants, about which he says, "It won't hurt anything and it's probably therapeutic.") He also rates what he identifies as "classic concoctions," practices that have been in use since before 1950.

In the back of the book there is an extensive bibliography, detailing sources for much of the research the author has relied upon for his recommendations. Where necessary, he has done the scientific research himself, such as in the beer as fertilizer question (where the final results indicated that "beer is better consumed than applied to your garden.") Beer does, however, get a four-flower recommendation as a slug killer, so long as the traps are set up not only to attract the slugs but to catch them as well. In the fertilizer department, eggshells are a five-flower solution, although they shouldn't be your only source of fertilizer. The author suggests four to five crumbled shells per plant, mixed into the soil around the plant, in the garden or in a pot.

Most of us are familiar with the practice of some gardeners who sprinkle today's used coffee grounds around their plants as additional fertilizer or as a soil acidifier. Dr. Gillman indicates that, to have any impact on the plants, the coffee grounds must be incorporated into the soil. Further, he says, not every plant benefits from the addition of coffee grounds; lettuce benefits quite a lot, while tomatoes do not. There are better soil acidifiers.

One theory around since the early 1900s suggests that it is beneficial for good pot drainage to have a layer of gravel covering the bottom of the container. To my surprise, Dr. Gillman illustrates how this practice actually increases the amount of water in the growing medium above the gravel, as well as hindering the movement of water from the top of the container through the gravel and out of the pot. His advice is to use a good-draining medium in the entire pot, adding perlite if you think it necessary to have even better drainage.

The practice of using dish soap to control insects has been around since the 1700s, according to the author. He even cites a recipe for a mixture of urine and soap from the early 1800s for getting rid of aphids on melons (don't try this at home!). Dish soap is thought by many gardeners to be effective in washing off the waxy covering of insect bodies at a fraction of the cost of commercial insecticidal soaps. Unfortunately, the commercial insecticidal soaps have been specially formulated to protect the waxy cuticle of the plant; dish soap has not, and can cause wax removal, leading to loss of water, leaf scorch, and death of the plant. The author's conclusion is that, without first testing your dish soap on plants you are willing to sacrifice, you are playing Russian roulette; moreover, today, more and more soaps are antibacterial and even more harmful for plants than the old-fashioned variety. This is certainly an instance when the extra money spent on a commercial product is money well spent.

In the area of weed control, mulching has been around since at least the 19th century. In fact, Dr. Gillman calls it "Mulch, the Magnificent" and gives it five flowers, although he goes on to say that you must pick the right mulch for your situation to achieve the best results. For seed sprouting and new plants, he thinks straw or sawdust are the best mulches. He only recommends grass clippings for established plants, as grass can actually inhibit the growth of other plants or the sprouting of seeds.

Both organic and commercial solutions to gardening problems are analyzed in this book. Some excellent charts are included, eg. a comparison of organic fertilizers, the rates of success of various treatments for black spot and powdery mildew, a comparison of various commercial and organic pesticides, and the preferred pH numbers for some common household plants. This would be a valuable book for any even slightly serious gardener to own. The author's "Take Home Message" is to search for the why behind everything you do for your plants. Then you will know why beer cannot make plants grow.

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