|
Baking soda claims range from controlling powdery mildew to battling ants and slugs, killing weeds, and helping your tomato plants grow sweeter fruit. This “natural” cure-all is, unfortunately, not able to live up to all those claims.  Before we get started, let me step up on my soapbox about the use of the word ‘natural’.
As a proponent of organic gardening and least harm, it irks me when people say natural is better, because sometimes it isn’t. Malaria, death cap mushrooms, and the flu are all natural. Just because something is natural does not necessarily mean it is what you want in your garden. ‘Nuf said. Baking soda as weed killer Just dump baking soda on top of weeds and they will die! True? Yes, probably. Good idea? No, definitely. Baking soda, or sodium bicarbonate, is a type of salt. Remember reading about victors salting the fields of their enemies? This was done so that the losers couldn’t grow any food in those fields. Sprinkling handfuls of salt around your garden is never in your plants’ best interest. Baking soda and soil pH Baking soda is highly alkaline. You will find countless articles pointing to the use of baking soda as a way to boost flower production and improve fruit sweetness because of this increased alkalinity. This is only partially true. While improper soil pH can impact fruit and flower production, simply adding baking soda is not the solution. Low flower production can have many causes: not enough or too much sunlight, improper fertilizing, irrigation, or placement, pests or disease, or nutrient imbalances in the soil. Fruit sweetness or acidity is more often a function of irrigation levels and overall plant health, than anything else. To boost the flavor of your tomatoes and many other crops, forget the baking soda and try deficit irrigation. If soil pH is making it difficult for your plants to absorb nutrients, you can try altering it, or you could select plants better suited to your local soil. Altering soil pH is difficult and it requires accurate testing and regular treatments. Simply sprinkling baking soda on your soil is more likely to raise the salt content to toxic levels. Baking soda as pesticide You have probably read that you can mix baking soda with sugar to create the perfect DIY ant poison. Supposedly, the ants take the mixture back to their colony, where they eat it and then explode. Nope. Doesn’t really happen. Think about it. From an ant’s perspective, the sugar granules are probably about the size of a tennis ball and easily discernible from the baking soda bits. Plus, I could not find a single piece of scientific research to back up the ‘exploding’ claim. As for slugs and snails, well, baking soda is a salt. Salt does terrible things to slugs and snails. Better to feed them to your chickens or just step on them and be done with it. Baking soda as fungicide Countless ads and articles point to baking soda as a fungicide. This is because most fungi grow best in a slightly acidic environment and baking soda has a pH of 8.4, which is more alkaline. When conditions become too alkaline, fungi stop growing. Until conditions improve, that is! Then, they take up exactly where they left off. Because of this, baking soda is considered fungistatic, and not a fungicide. Also, while baking soda’s fungistatic properties are well documented in lab situations, those results have not translated to outdoor growing conditions, such as are found in your garden. If you can completely cover a surface with a baking soda solution, you may be able to temporarily halt the development of any resident fungi, such as those that cause black spot or powdery mildew. But, right away, problems begin to occur. First, ever-increasing amounts of baking soda are needed for the same effect. Also, being water-based, the solution needs to be replaced after every rain, and each treatment adds more salt to the soil than is healthy for plants or important soil microorganisms. You can, however, mix baking soda with horticultural oil for moderate, but inconsistent, results. Just be aware that phytotoxicity can occur. [Phytotoxicity means ‘poisonous to plants’.] When combatting powdery mildew, better results can be obtained by using potassium phosphate, potassium carbonate, sulfur, or even milk sprays. That being said, baking soda solutions can slow the development of certain fungi on produce after it has been harvested. Commercial growers frequently treat thick-skinned produce, such as citrus, with a boiling bath of baking soda in solution to prevent fungal growths while the fruit is in storage or being shipped. This is because the fungi that cause the blue and green molds on citrus are particularly sensitive to alkalinity caused by baking soda. In fact, that’s where the whole baking soda craze got started - from a test on citrus molds conducted in the 1930s. You may be surprised to learn that the use of a coarse organic mulch, such as arborist wood chips, provides better disease suppression than baking soda treatments. This occurs because the wood chips make life more difficult for fungal spores. Baking soda performs wonderful tasks in the kitchen, making muffins, deodorizing the fridge, and putting out grease fires. Let’s leave it there, where it can do the most good, and not in the garden. Sprinkle cornmeal in the garden to stop weed seeds from germinating! Cornmeal prevents fungal diseases, too! Wouldn’t that be convenient?  Cornmeal (Popo le Chien) CC BY-SA 3.0 Like many other garden fantasies, the fallacy about cornmeal originated in fact, but the above claims have not been able to withstand the tests of time and science.
How the cornmeal myth began In 1985, Dr. Nick Christians, from Iowa State University, found that corn gluten meal, a byproduct of the corn milling process, showed herbicidal effects during a turfgrass experiment. The corn gluten meal was found to desiccate newly forming roots of small-seeded plants in highly controlled greenhouse environments. As such, corn gluten meal can act as a pre-emergent herbicide, an idea that was patented in 1991, but those results have not been repeatable in outdoor environments, such as family gardens. What is corn gluten meal? Corn gluten meal is not the same thing as the cornmeal you find at the grocery store. Instead, it is what is leftover after the corn has been ground up to make cornmeal. Corn gluten meal is a byproduct used in livestock and pet food. It is the primary protein found in corn and does not actually contain true gluten. Corn gluten meal is not species specific, so it will, when conditions are just right, desiccate any new, small-seeded plant roots, including your lettuce, carrots, and many others. On the other hand, corn gluten meal contains 10% nitrogen, so sprinkling it on your lawn or garden will provide this important nutrient, leading to lush growth and healthier plants, weeds included. [Cornmeal has practically zero nitrogen.] Cornmeal as fungicide Popular claims also state that cornmeal will help control fungal diseases, such as brown patch, black spot, and dollar spot. That’s strikes me as funny, because cornmeal agar is produced as a medium specifically designed to grow fungi for laboratory work! Finally, for the record, ants do not “explode” or die in any other fashion when they eat corn gluten meal, cornmeal, or other foodstuffs. In fact, ants, rats, squirrels, and many other garden pests love cornmeal and corn gluten meal, so choose your battles wisely. If you want to get rid of weeds, cut them off at ground level before they go to seed, and apply a thick layer of mulch. Now you know. For generations, mothballs have been celebrated as a way to keep rodents, snakes, and insect pests out of the garden. Don’t do it.  Mothballs (Public Domain) Popular claims about mothballs in the garden
In one article, you are urged to add a few mothballs to a potted plant and then cover the whole thing with a plastic bag for a week as a sure-fire way to get rid of insect pests. In another post, you are told that adding mothballs to the garden will repel mice and rats. Then a friend urges you to scatter mothballs throughout your garden to deter squirrels, snakes, and rabbits. Is any of this a good idea? No, it isn’t. What are mothballs, anyway? You might remember smelling mothballs in your grandmother’s closet, attic, or basement. That distinct scent is unmistakable. Mothballs are spheres or disks of pungent chemicals that slowly evaporate into a gas that is toxic to moths and moth larvae. This is why people have used them to protect clothing and other fabric materials while in storage. The chemicals used to make mothballs can be naphthalene or paradichlorobenzene, both of which are carcinogenic neurotoxins that have no business near your food. There are clear and important instructions on how to use mothballs properly, if you must. For one thing, containers must be completely sealed to prevent long term exposure and the associated health risks. The truth is, it is illegal to use mothballs as a pesticide in many states. According to the National Pesticide Information Center, using mothballs outside poses a risk to children, pets, and local wildlife. Mothballs can also contaminate soil and water. So, the next time someone suggests using mothballs in the garden, you can protect them by educating them. Eggshells contain calcium. Plants need calcium. Lack of calcium causes blossom end rot. Therefore, adding eggshells to the garden will prevent blossom end rot and feed my plants, and snails won’t cross a line of broken eggshells, right? Wrong.
Eggshells and decomposition
As stated above, eggshells evolved to provide protection. Unless you are dropping eggs off the gym roof for a high school physics class or cracking them against your kitchen counter, shells are tough. They don’t even break down in boiling water. The moisture and microorganisms responsible for decomposition do not have a ghost of a chance of breaking down an eggshell in your lifetime. For example, 170 years ago, Thomas Jefferson raised chickens and ducks. An archeological excavation of the site found that eggshells from those birds were still intact in the soil. So, no matter how often you flip that compost pile, those eggshells will never significantly improve anything in the garden. Even if you let them dry and crush them into smaller bits, those bits are very unlikely to break down enough to be usable by your plants. Unless you have very acidic soil (<6.8 pH) and the eggshells are ground into a fine powder, they will add nothing to your soil. Eggshells and blossom end rot Blossom end rot is a condition that occurs when plants cannot move calcium to where it is needed. Calcium is an immobile nutrient because it takes a lot of water to move it around inside a plant. Calcium shortages can be due to low calcium levels in the soil [generally east of the Rocky Mountains] or irregular irrigation habits [generally west of the Rockies]. Get an inexpensive lab-based soil test from your local university or soil test lab to learn exactly what your plants are dealing with. Eggshells as a pest deterrent Crushed eggshells are said to be a barrier against slugs and snails, cutworms, and even deer. Those claims are false. The only thing you might find is some birds will be attracted to the shells, either through natural curiosity or as a calcium source during the egg-laying season, and some rats looking for a snack. I crush my eggshells and feed them back to my chickens. I don’t know if they eat them, but I think they do. Just in case, I offer oyster shells, as well, and water my tomatoes regularly. Epsom salts are wonderful in the bath, but they do not belong in the garden. Popular culture touts epsom salts as a garden miracle worker, but the truth is, adding Epsom salts to soil nearly always ends badly for plants.  Epsom salts (Public Domain) False claims about Epsom salts
The sheer volume of claims made about Epsom salts should be the first clue that there is a problem. Epsom salts are said to improve flower blooming, germination, photosynthesis, the uptake of other nutrients, fruit production and flavor, and to act as a valuable nutrient for overall health. Epsom salts are said to “enhance a plant’s green color” and “help plants grow bushier” while deterring pests, reducing blossom end rot, transplant shock, leaf curling, and chlorosis (yellowing). Epsom salts are also said to be a safe, reliable weed killer. With all these miracles provided by Epsom salts, why isn’t everyone using it all the time? Many advertisements and articles also state that Epsom salts are not persistent in the soil, so you cannot overuse it. Wouldn’t it be wonderful if all those claims were true? Unfortunately, they are not. The truth about magnesium sulfate Epsom salts, also known as magnesium sulfate (MgSO4), is made up of magnesium, sulfur, and water. Magnesium and sulfur are plant micronutrients. This means plants use them, but only in very small amounts. If a magnesium or sulfur deficiency has been identified via a lab-based soil test, Epsom salts can be safely used to counteract those deficiencies (assuming your soil is equally deficient in both nutrients at the same time). That’s also only after you are certain that the deficiency is not being caused by too much or too little of another nutrient. For example, too much phosphorus in the soil can make it difficult for plants to absorb magnesium, regardless of how much is present. [Are you beginning to see how important that soil test is?] Adding too much magnesium can cause just as many problems as having too little. More often than not, your soil probably has more magnesium than plants need. When I bought my house in 2012 and sent a sample out for a soil test, my results came back with 798 parts per million (ppm) for magnesium. The optimal range is 50 - 120 ppm. Whoever lived here before me kept adding more fertilizer (or Epsom salts), long after it was needed. Crops that commonly need magnesium include apples, beets, citrus, peppers, potatoes, tomatoes, and watermelon. Usually, deficiencies only occur when these and other crops are being grown intensively, and rarely in the home garden. There is no scientific evidence of Epsom salts repelling slugs, insects, grubs, voles, rabbits, or anything else. As for the blossom end rot claims, adding Epsom salts may actually interfere with your plants’ ability to take up calcium, making it more likely that your tomatoes will develop blossom end rot, rather than preventing it. Epsom salts may sound like a garden cure-all, but those claims should be filed under “too good to be true”. A healthy, productive garden does not come with quick fixes. Before jumping on a bandwagon, be sure you take the time to read the science behind those claims. And get a soil test. Your plants will be healthier and more productive, and you can save Epsom salts for the bath, where they belong. |
Welcome!You can grow a surprising amount of food in your own yard. Ask me how! To help The Daily Garden grow, you may see affiliate ads sprouting up in various places.
You can also get my books, Stop Wasting Your Yard! and What's Growing Wrong?  Index
All
Archives
November 2024
|
RSS Feed