There are so many ideas for improving your home garden that have grown up over the years, that it is difficult to keep them straight. And quite a few come from pretty reputable sources.
For example, I first heard about adding soil inoculant (nitrogen fixing bacteria) to the soil from Jim Crockett’s PBS program some years ago. The idea was that since legumes like peas and beans would utilize these bacteria to promote growth.
Well, you will find extension sites like this one at Penn State describing the use of soil inoculants, but they are clearly talking about full scale agriculture, not a home garden. But, according to Linda Chalker-Scott, who runs the Garden Professor’s Blog “There is absolutely no science behind using it in nonagricultural situations,” and that you should save your money. She notes that there are no studies that show such soil inoculation is useful in the home garden. Scott is also an Extension Professor at Washington State University, and the author of several gardening books.
Copper deters slugs?
Any number of writers have suggested that copper, even copper pennies can be used to deter slugs. They usually cite some unlikely sort of galvanic shock the slugs receive crawling over copper. This just plain doesn’t happen. In this article, you will see why that is silly, as well as a movie showing it doesn’t work. And the amount of actual copper in a U.S. penny is negligible in any case.
This probably came from the idea of using sharp copper edging along beds, which would cut slugs who tried to climb over it. That will work, but copper is expensive. And sharp edging would do, though, as well as using diatomaceous earth, which contains fossilized remains of diatoms, a top of hard shelled algae. Be sure to get the grade designed for your garden, not for swimming pools.
Frankly, the best way to deter slugs in large garden beds is still metaldehyde, but it is dangerous to pets. In such situations, iron phosphate is also effective.
Saucers of beer will draw slugs to them and drown them, but unfortunately, they actually attract slugs, and have to be emptied daily.
A final solution for slugs is to keep some ducks. They apparently love slugs.
Marigolds deter nematodes
If I have a square bed with some space in the middle, I often stick a couple of marigolds there. It’s colorful enough, but the idea that it might deter nematodes or other bugs is only true when you plant them ahead of time. About 2 months earlier. This clearly only would work in long growing season regions like Florida. Marigold roots secrete alpha-terthienyl into the soil, which will kill nematodes when you plant your main crop. Otherwise, you are just decorating your garden and that is not such a bad idea.
In some cases, marigolds can become slug magnets, and the slugs will strip the marigolds. This is not very helpful.
The idea that planting various crops near each other, called “intercropping” seems intuitively appealing, but you will discover than there is simply no science behind it. As Linda Chalker-Scott describes on her Horticultural Myths page, there is little science behind companion plantings.
The “Three Sisters” planting associated with native Americans planted corn, beans and squash together, so that the bean vine climbs the corn and the squash fills in the ground space. This only works because the three plants have similar growing requirements and don’t out-compete each other for nourishment.
Beyond that one case, much of the writing on companion plantings borders on pseudo-science and the occult, she notes, and “traditional lists of plant associations have entertainment, not scientific value.”
Trap cropping is a special case of intercropping, where you plant a crop a couple of weeks ahead of your main crop, so that it attracts the pests away from your cash crop. In the linked paper, the researchers note that planting Blue Hubbard squash ahead of your main squash or cucurbit crop. This will attract the squash vine borers and cucumber beetles to the trap crop, and you can then plant your squash or cucurbit seeds. This probably is not relevant to home gardening, though.
Bone meal (according to Dr Chalker-Scott) is primarily calcium and phosphorus, which are usually available in garden soils in sufficient quantity. So when you plant your spring bulbs, you might as well skip buying the bone meal. The only thing it might do is induce your dog to dig them up.
You make a compost tea by mixing compost with water, letting it soak and then straining through cheesecloth or the like and using it in your garden. You may recognize that this description is very vague and thus the results are quite variable. While there is some research suggesting that compost teas may deliver soluble nitrogen as fertilizer, creating such a tea really requires a laboratory rather than home brewing. And there is a significant danger of human pathogens in the resulting solution. I recommend having the best watering system there is, click over here if you want to get the best quality of water as possible.
Papers on the Horticultural Myths page suggest that compost teas
- are not very effective for pest control,
- little effect on disease suppression.
- Aerated teas are also ineffective for disease suppression and may harbor human pathogens
There are any number of other myths debunked on the Horticultural myths page and in the books below. They are fun to read.
- Linda Chalker-Scott, How Plants Work
- Linda Chalker-Scott, The Informed Gardener Blooms Again
- Jeff Gillman, The Truth About Garden Remedies
- Jeff Gillman, The Truth About Organic Gardening
- Jeff Gillman and Meleah Maynard, Decoding Gardening Advice
- Horticultural Myths
- The Garden Professor’s Blog