Jeff Gillman doesn’t name names but he doesn’t have to. We all know who he’s talking about when he refers to gardening “gurus'” recommendations that we douse our gardens with shampoo, beer, hydrogen peroxide, and a myriad of other common household substances. (I won’t bother naming names either, but the other ranters have here and here.)

But while we may instinctively diss witch-doctor garden potions as silly and possibly harmful, Gillman’s book goes much further. With degrees in horticulture and entomology, Gillman is an associate professor at the University of Minnesota, where he teaches courses on nursery management and researches plant production. For this book, he has researched and/or field-tested every home or folk remedy he discusses. He also discusses commercial fertilizers, pesticides, and biostimulants, according to the chemicals they contain. The home remedies are divided by what they do (fertilize, control pests, etc.). Each remedy is discussed in four steps: theory, practice, the real story (in which the remedy is tested) and a final “bottom line” conclusion entitled “what it means to you.” There is a flower rating for each remedy, from one (fuggidaboudit) to five (likely benefits if used correctly).

So let’s cut right to the chase. This is what he would say about a remedy like the following:

Overspray your lawn with my Lawn Freshener Tonic: 1 can of beer, 1 cup of dishwashing liquid, 1/2 cup of ammonia, and 1/2 cup of weak tea water mixed in your 20 gallon hose-end sprayer, and applied to the point of run-off.

1. Beer is thoroughly debunked. I didn’t need Gillman to tell me “Beer is better consumed than applied to your garden,” but it was interesting to learn why. Gillman’s research included testing a buddleia with Michelob Light, Guinness, and Sharp’s. First, any alcohol is bad for plant growth, second, the beer increases the growth of harmful bacteria.

2. Soap is used here as a wetting agent, but according to Gillman, household soaps are not formulated for garden use, could burn foliage, and, at best, are a waste of time and a substance that works much better on dishes. Deep watering is the better and more effective choice.

3. Household ammonias contain a type of aqueous nitrogen that hurts, not helps, plants. Without intimate and precise knowledge of the exact formulation of your household ammonia, your soil, and the correct calibration needed on your hose-end sprayer, you could be harming your plants. Which isn’t really the idea.

It should come as no surprise that Gillman speaks highly of compost, mulch, and organic fertilizers—i.e., stuff that’s actually made to be safely used in the garden. He isn’t too enthusiastic about commercial pesticides, noting that while we look back in amazement at the deadly toxins our forefather used, others may think the same about us someday. However, he does provide a long list of the various commercial preparations (some safer than others) and explains how they work.

I was very interested in the section devoted to the effect of music on plants. In addition to noting The Secret Life of Plants, Gillman cites Dorothy Retallack’s lesser-known The Sound of Music and Plants. The idea is that the sound effects the plants’ stomata (pores) causing them to close or open (depending on whose research you are reading). Open stomata might allow fertilizer to be more easily absorbed, while closed stomata could conserve water. It seems like something does happen when plants are exposed to music, but Gillman can’t pin it down. This is the only remedy about which he is unable to come to any conclusion—even after subjecting his plants to the Canadian band Rush for two weeks. (I call that cruel and unusual.)

This is a must-have book for both its information on home remedies and its survey of commercial remedies. Clearly, we need fewer gurus and more people like Gillman. Watch for Gillman’s guest post on this blog Wednesday, in which he gives a “top four” list of the most infamous (in his view) garden gurus—I had no idea there were others besides Baker—in which he does name names and says other things he couldn’t say in his book.