Timber Press invited me to be one of the stops on Jeff Gillman’s blog tour. Jeff is “traveling” around the country, promoting his two books, The Truth About Garden Remedies: What Works, What Doesn’t, and Why and The Truth About Organic Gardening: Benefits, Drawbacks, and the Bottom Line, from the comfort of his office computer. Besides a review of each book, Jeff will be blogging two guest posts that we both think you will find informative and thought provoking. Also, two lucky readers will win a free book courtesy of Timber Press. Details on how to win a copy of The Truth About Garden Remedies will be in tomorrow’s post and in a forthcoming post I’ll tell you how to win a copy of The Truth About Organic Gardening.
I confess to being a bit skeptical of skeptics. It’s easy to set up a straw man–an opponent that’s easy to knock down–by tipping the odds in your favor. And it’s a lot more difficult to set up a rigorously fair experiment that can take into account all the factors that might influence the outcome–some would say it’s impossible. So I thought I would just page through this book and give you my reactions and observations, listed by the chapter headings found in The Truth About Garden Remedies. It wouldn’t surprise me if Jeff has something to say about some of my remarks.
Fertilizers and other soil amendments
In regard to the ratio of nutrients in various fertilizers, I found Jeff’s assertion that the “claimsâ€¦are usually basically true [but]â€¦are usually out of line with the magnitude of the effect that different fertilizers will have” enlightening and reassuring. I don’t fertilize most of my soil-grown plants unless I’m feeling particularly insecure about a particularly expensive or sentimental plant. Container grown plants are another story. It’s nice to know that if the petunias are looking peaked, I don’t have to use fertilizer specially formulated for flowering plants; a general all-purpose fertilizer will do.
In regards to buttermilk, I’ve never seen this promoted as fertilizer. I’ve often seen it suggested to prepare a surface on which you want to encourage moss to grow, which Jeff doesn’t address at all. How about it, Jeff? Can buttermilk promote the growth of moss?
From Jeff: I’ve heard of this too, but haven’t tested it yet. It seems like a reasonable suggestion, but without proper testing……
I’ve been told before by local gardeners that Epsom salts will help my blueberries grow. Jeff says that Epsom salts add sulfur and magnesium to the soil without raising pH, and that soils low in magnesium tend to be acidic. Blueberries like acidic soil, so I can see that this may actually be good advice. Of course, only a soil test will reveal if my blueberries actually need additional magnesium and sulfur, but at least I know this home remedy has some basis in fact.
I have heard gypsum recommended to treat roadside soil contaminated by the salt spread on the roads in winter. According to Jeff, gypsum does displace sodium, and adds sulfur and calcium without changing the pH. Jeff uses gypsum in container plantings of tomatoes, which “have a relatively high demand for calcium but usually don’t need to have the pH of their media altered.”
To test the effect of soda, syrup and other sugary concoctions as fertilizer, Jeff set up a hydroponic experiment. I didn’t think this was fair. If the advocates for this “believe that these substances feed good bacteria in the soil,” shouldn’t plants growing in soil have been included in the experiment? He did go on to cite research done with birch trees, but the hydroponics experiment seemed like a case of setting up a straw man.
Jeff: I use hydroponics to give me rapid assessments of what will happen when I add a particular thing to a plant’s root system. Generally hydroponics do work well in predicting what will happen in soil. However — Yes, this is a bit of a straw man experiment — I did stack the cards against adding syrup. But, I stand by my conclusions and would add that other research including some more recent work by a group in Canada has shown that adding sugar to the soil actually pulls nitrogen out of it (through an increase in a particular type of bacteria).
In another case of setting up a straw man, Jeff and colleagues applied antiperspirants to plants to test the efficacy of antitranspirants. Huh? Why did we have to invent a new homemade remedy to test the worth of something designed to work on plants? Especially when there is apparently other research out there documenting “that winter protection just isn’t the best use of antitranspirants.” Since I had thought that winter protection was the primary reason that antitranspirants were developed, I would have liked more information about the bona fide research done to test them instead comparing them to products created for humans.
Jeff: Fair enough. I enjoy trying different and off-the-wall things. Some people enjoy reading about them and some people don’t. I’m sorry that you didn’t get all that you wanted out of this section, but for me it was one of the most fun sections to write.
I learned a long time ago (in an ancient issue of Fine Gardening) that gravel at the bottom of a container doesn’t improve drainage. I’ve recently been given a sample of Better than Rocks, a product that is supposed to be better than gravel for drainage in containers. Somehow, I suspect not. I do use a single piece of broken pottery over the hole in the bottom of the pot, but this is not for drainage so much as to keep the potting soil from leaking out. The curved piece of pottery lets the water out but not much of the potting medium.
The first time I used hydrogels, they were included in the potting soil I bought for my window boxes. I am a terribly neglectful waterer, and my windowboxes seemed to fare better than usual with the hydrogel included. They saved my bacon a number of times. But Jeff says they don’t work. I can’t prove him wrong, because I have never done an experiment where one window box has them and the other doesn’t. Because of my own experience, I am willing to pay a little more for potting soil with the hydrogel in it, though I’ll still buy the regular stuff if the “improved” potting soil isn’t there.
Jeff: Lots of people disagree with me on the hydrogels — and all can can say is that, if you think it works — keep on using it. But after testing dozens of plants and reading dozens of papers there just isn’t much evidence that they work particularly well (if they work at all).
Jeff says, “There is not a great deal of scientific literature that lists willow diffusate‘s [willow water] usefulnessâ€¦[and I] have found it to be much less effective than commercial rooting aidsâ€¦” This was quite the shocker for me. I don’t do much rooting of anything, but I thought willow water was a time-honored remedy that works. According to Jeff, it only “works” on cuttings that root easily anyway, and they would root in plain water just as well. Shucks. We have a lot of willow growing on our property.
Dish soap is a common ingredient in many homemade garden remedies, and Jeff discusses the pros and cons in this chapter. But what I have always wanted to know is whether it makes any difference whether it is dish soap or dish detergent. Some recipes emphasize that it must be dish soap, which is much less common and more difficult to find. What do you think, Jeff?
Jeff: Dish soap and dish detergent can both work well, as can shampoo or laundry soap. The key is that the soap (or detergent) is able to wash the insect’s cuticle off — any good surfactant (a surfactant is something that allows oil and water to mix) should accomplish this. Unfortunately it could lead to the plant losing its cuticle too — and cause leaf burn.
Fungicides and other disease control agents
My big bug-a-boo, botrytis, was not mentioned in this chapter, much to my regret. But did you know the best treatment for powdery mildew is to spray the foliage with water? Sounds counter-intuitive, which makes me wonder if I really know what powdery mildew is.
I still haven’t hit the Herbicides, Other Pesticides and Protectants, Commercial Pesticides, and Concoctions to be Avoided chapters, but by now you get the idea. You will definitely learn something, definitely disagree with something, and definitely wonder about something the book doesn’t cover if you pick it up and read it all the way through. But what if you run across a remedy that Jeff doesn’t cover? How do you go about doing what Jeff does in his books, figuring out what really works? In a few short days, Jeff will be posting here himself, explaining how to do just that.
Jeff: This is definitely one of the best reviews of my book that I’ve ever seen. Kathy has looked at it critically, made judgments for herself instead of just accepting my words as gospel, and basically done everything that my book is intended to promote (read my conclusions chapter next Kathy). I can’t ask for anything more. Thanks, Kathy.