Gardening secrets: Epsom salt and sugar

This veggie bed soil isn’t very active. So I buried frosted tomato vines in it and sprinkled on my powerful duo, and in a month I’ll plant seeds.

Gardening shouldn’t be expensive.  If you believe everything you read, especially those wonderful gardening catalogs and even advice from professional gardeners, a garden could be quite an investment.  Talk about golden carrots!  I have spent my fair share of money for gardening products in my time.  Then this permaculture stuff got into my head and it makes me rethink everything.  Permaculture proves that gardening shouldn’t be labor intensive, just labor-wise.  Make things work for you and let plants get on with what they want to do.  Makes some forehead-slapping sense to me.

Organic fertilizer is a plus for firing off poor soil, but it is expensive.  There are two other very inexpensive household products that you can use to really charge your soil, promote growth, make fruit sweeter, reduce some weeds, release the bound-up vitamins and minerals in the soil, promote world peace… well, I’m getting a little carried away, but not by too much.

Epsom salt is named after Epsom, England, where the active ingredient Magnesium sulfate was originally created.  Not found naturally, it must be processed, now most often from dolomite.  Dolomite is mined in the United States and internationally.  The sustainability of dolomite mining and the environmental impact of mining, processing and shipping Epsom salts may be something to consider, if you worry about the locality of products you purchase.  I don’t know what impacts those are.  Epsom salts can actually be made at home by chrystalizing magnesium sulfate, but I’m thinking that although I enjoy do-it-yourselfing, this is a little too much.  Perhaps I’ll change my mind one day.

Epsom salt is inexpensive and readily available.  It is recommended for tomatoes, peppers and roses, but I use it around citrus trees, in the veggie beds, and anywhere leaves are looking sickly.  The Epsom salt bag recommends sprinkling 2 tablespoons around the base of each plant, so you can see a little goes a long way.  It is also a wonderful bath salt which eases sore muscles and leaches impurities from your skin (often recommended as a diet aid because of this). (Also if you have a greywater system, your magnesium-enriched bathwater will flow out to nutrify your plants!  Such a deal!)  Some sites tell you never to take it internally; the bag and others recommend it for… let’s say… loosening things up inside.  It is also used as a curdling agent in making tofu.  There is a relationship between calcium and magnesium whether it be in the soil or in our bodies.  They need each other in a ratio of about 2:1 calcium to magnesium for best absorption.  (Dairy products don’t have that ratio, so if you drink milk you may not be absorbing the amount of calcium you thought you were).  Also, calcium and potassium compete with magnesium for uptake into roots, and even though your soil samples may indicate enough magnesium your plants may not be receiving enough.  Here are some good sites for looking into the science behind it if you’re interested: National Gardening Association, a book excerpt here which goes into more details about how its made and how to use it medicinally, and even a site about how to make crafts with it.

Also, don’t let the name confuse you.  Epsom salt is Magnesium sulfate, not salt as in table salt which is Sodium chloride.  Applying Epsom salt to the ground is not like applying, well, salt.  Applying Sodium chloride to your soil is to kill it.  I’ve read and overheard inexperienced gardeners say that they’ve poured salt on weeds because, after all, it comes from the ground so it shouldn’t do any damage.  Ummm, no.  Invading armies would salt the fields of their enemies so they couldn’t grow crops there for decades.  Heavy salt in the soil is a huge problem (which, of course, if you’ve been paying attention to past blogs you know can be readily solved by….. what?  I’ll give you a chance to fill that in and reveal the answer at the end!)

As for my other ‘secret’ ingredient is sugar.  Yes, my soil is on junk food.  Actually using organic molasses dissolved in rainwater would be best, and I have done that when making a microbial brew, but I am but one person with a thin purse so sugar it is.  Why sugar? It is a complex carbohydrate which plants need to produce protein, starch and fats.  Plants produce their own sugar through photosynthesis, and by secreting their own sugars through their roots determine which microorganisms they want to thrive near them.  I use a little sugar on ailing soil; all those millions of microbes and fungusey things that are in the soil get a jump-start with something sweet. Have you ever made bread and mixed a little sugar in with the yeast to proof it?  Same difference.  The soil critters feed off the sweet, multiplying like crazy and making your soil turn into healthy goodness. If your soil is healthy, you don’t need it. When the sweet is gone they munch on organic materials processing them more quickly and opening up all those locked nutrients in the soil.  If there isn’t enough for them to eat and there is a die-off, then their little bodies become nutrients for the soil (as they would anyway).  To put this into perspective, let me relay to you an interesting fact I learned in my Permaculture Design Course. When a field is plowed and farmed, the first year crops are good.  Each successive year that it is plowed and farmed the fertility is less and the crops worse until the ground is barren.  That is because with the first plowing or tilling gajillions of microbes are slaughtered and it is their dead bodies that fertilize the crops.  Each successive year there are fewer microbes available to slaughter until they are all gone and the soil has become dirt.  And then we have dust bowls and run-off, erosion, loss of the water table, the drying up of streams, climate change, universal discord… well, you get the picture.

Climbing Don Juan here was a miserable, spotty rose last Spring, while all his friends were tall and lovely. I added Epsom salt and sugar, and he fought off the black spot and is thriving.

Only lightly sprinkle the sugar around your soil; too much can hurt plants.  I have used sugar successfully to kill off an invasion of nutgrass, something about which I read on the Internet.  This sedge turned up in my pathways and although I hand weeded the little guys (I didn’t eat them although they were cultivated as a crop in Egypt) they just kept on coming, even after I had put plywood over the top for awhile.   So I sugared them then threw the plywood back on, and Bob’s your Uncle, no more nutgrass in that area.   I envisioned millions of little mouths biting away at the nutgrass bulbs underground… I need to stop thinking about that.  What really happened is that the microbes fed off the sugar and multiplied wildly to a point where they locked up the available nutrients in the soil which non-natives need to grow.  Native plants won’t be bothered because they can thrive in poor soil. Here is an article about the research behind sugaring to prevent weeds.  I lightly add sugar around established plants that aren’t doing well, and water into new vegetable beds where the soil isn’t vigorous yet and allow the beds to sit awhile before I plant seeds.

Refined white sugar is of course empty calories.  Any dissolved sweet will work well, too.  Beet sugar, agave syrup, leftover pancake syrup, sorghum syrup, honey, molasses, diluted jelly… use your imagination and your pantry.  The more nutrients in the sweet the better for your soil, but also the more expensive it will be.  If you are using sweet for houseplants then you should be wary of possible interest by house ants.  Outside it isn’t a problem.

So share your bath and your jelly donut with your garden and you’ll both be happier and healthier!

(Answer: compost!  You knew that!)

18 thoughts on “Gardening secrets: Epsom salt and sugar

  1. Hi Nolan, thanks so much for reading my site and for your kind comments. I hadn’t seen those sites but have visited them on your recommendation. Great to see explorations of soil science. The field broadens all the time; even Elaine Ingham said that when she studied soil in college it was very narrow, and everything she knows now she learned since then (and has been instrumental in discovering and identifying microbiota). Thanks for sharing the sites.
    Most people work with dirt rather than soil. When I was writing the post about Epsom salts, I was working with dirt. To add a dose of magnesium to the dirt a little Epsom salts is great, and combined with sugar to help generate microbial activity really works. But if you have soil, then only compost is needed. If a plant is sick, then a foliar spray of actively aerated compost tea will do all the work. The only time I’ve used something different at Finch Frolic Garden was when we discovered a particularly heavy infestation of scale on a passionfruit vine. We made a very dilute spray of Dr. Bronner’s peppermint soap and water and sprayed that on the affected leaves twice, and that worked fine. Otherwise we don’t want to risk spraying the beneficial insects or killing the microbial webs that coat the healthy plants. I wouldn’t use Epsom salts as a foliar spray unless you have a very sick plant and dirt. AACT is all about growing an inoculation of microbes in a food solution, and Epsom salts wouldn’t help them grow. Any concentrated form of anything will kill some of those little soft-bodied microbes, so I’d avoid using anything that wasn’t a food in AACT. The addition of the microbes to the soil and their subsequent behavior allows the natural magnesium to become available to the plant roots. So, a long answer to a short question, but if you have good microbial soil and healthy plants then you really don’t need anything except more compost!
    Thanks so much again! Diane

  2. Hi. I love the site. Your series on plant guilds alone is fantastic. I found it interesting that you took Elaine Ingham’s course. Have you also checked out (Tim is lauded by the authors of Teaming With Microbes) or You would probably enjoy them. I was curious what you think the effect of using epsom salts (as a foliar spray as suggested by your linked article) for rose family plants might have on the microbes present? I’m curious if they could even be added to compost tea before being applied as a foliar spray.

  3. Hi Pam,
    sorry to hear about your snail farm! We used to have one here at Finch Frolic Garden prior to the garden being planted. Salt (sodium) has a reaction with the snail’s secretions and has a nasty burning reaction to them, desiccating them from the outside. Epsom salts is magnesium sulfide, and won’t have the same violent reaction, although any desiccant (even sugar) when dumped in quantity on them will hurt them. And you are right that you don’t want to salt your yard!!! You are on the right track with the beer, but your approach can be different. Instead of leaving the container of beer on the surface for your dog’s enjoyment, sink the container in the ground and then mostly cover it with something heavy, such as a piece of flagstone or a rock. This will protect the beer from the dogs, keep the beer from evaporating so quickly, and will attract more slugs and snails because they like to hide under rocks and wood. Use something like a margarine container sunk so the top rim is level or almost level with the ground. You don’t have to use beer, either. Anything yeasty, such as old fruit juice, will also work. Sprinkling sharp-edged materials such as broken up eggshells, oyster shell (feed stores have these cheaply for feeding to hens) will help deter snails with the added bonus that they don’t melt in the rain or irrigation and have to be reapplied, which sugar and salt would need, and they are good for the soil (particularly around tomatoes which love the calcium). With those drunken dogs around I’m sure you don’t have hens or ducks, both of which (particularly ducks) are excellent snail and slug eaters. Another organic method is to lay banana peels out overnight. The slugs cluster under them and then you can do away with them. Burying the whole thing several inches down would be composting without the poor things crawling to the surface. Look for clusters of eggs under the soil when you are working in the garden; those are snail eggs.
    I hope this helps. Good luck!!

  4. I live in Utah and my yard is infested with snails. I haven’t had a chance to garden because the nasty pests eat everything I’ve planted! I’m researching to see if sugar will get rid of them. I know salt kills them but salt is bad for plants? Does the Epsom salt kill snails? Will sugar kill them? I have dogs that drink the beer I put in jar lids and I’m not interested in poisons as I’m sure my canine kids will suffer as well. Any help would be greatly appreciated!

  5. Hi, no, the high alkalinity is pretty normal for our area. We’re mostly desert if you look beyond what imported water will do for homeowners. The water here has lots of calcium in it. My property is a food forest carefully watered with unfiltered well water, and the soil, which is mostly very solid clay except for a bit of decomposed granite, is amended by leaves, the exudates from the plant roots, and an occasional home-brewed actively aerated compost tea. I took the Dr. Elaine Ingham Soil Microbiology class a couple of years ago, which was incredible, and pretty much follow her precepts. (If you haven’t explored her work, you’ll be thrilled. It, like permaculture, goes far beyond ‘organic’ gardening precepts.) The sugar and Epsom salts blogpost was written prior to the class, but I still stand by the application of these on dirt (few microbes to hurt!) as a homeowner’s quick fix, followed by ‘habitat’ for the microbes (sheet mulching, several inches of leaves, compost, etc.). Actually, there are microbes in any soil that has habitat for them. The earth dwellers that thrive in high or low pH are just part of the healing process of the earth. Their life and deaths lead to circumstances in which different microbes and fungi can be successful, and so on. I have everything from stonefruit to bananas growing successfully here in this pH, by encouraging leaf drop and planting in tight plant guilds, and the only tending we do is to prune plants out of the pathways because they’re always trying to take over! Oh, and harvesting, which is heavy. By applying lots of any one thing, be it sulfur or whatever, you are killing off microbes that need to be there. So I guess what I’m getting at in this ramble is that once you’ve started microbial activity in the soil and given them good habitat, you can plant and have faith in the system without dumping on additives. Leaves and compost are it. My main concerns with the clay is drainage, which I handle by burying old wood around and under a new plant, and digging an exit lined with branches downhill from the planting hole for any pooled water.
    Thanks again for this conversation! Diane

  6. 8.5?!?! Yowza! Thats 100x less acidic than 6.5. I know this discussion is about how sugar interacts with microbes, but lets expand it a little further. Is that the pH of your yard, or is that pretty much all around? Yards can get less acidic if you water with tap water, that’s a problem that we have down here in Texas for some residents too. So back to microbes, giving them sugar can be really effective, but you might get better results with lowering soil pH to create a better home for them.
    (Davis, Jessica PHD) “Lowering soil pH is a slow and challenging process. “The truth is, lowering soil pH is hard, because the limestone in the soil continually dissolves,” says Jessica

    Applying sulfur is the best way to fix it, but the problem is you have to do it FOREVER!!


    P.S. I love Cali, if you catch wind of any renewable natural resource jobs or internships let me know!!!

  7. Our soil is 8 – 8.5; most of S. Cal is except for some areas near the beach. The more microbial activity in the soil, the closer to a neutral pH your soil, which opens up availability of micronutrients to plant roots. Interesting to hear about what your professor discovered. I would have thought that even in an acid pH, the more microbes there are the closer to a neutral pH the soil would become. I’d only add sugar to dirt or very poor soils to charge them up, along with a lot of organic matter. After the soil habitat is going well no other additives except more mulch (preferably leaves) is needed. Thanks again for commenting and for answering my question. More to research! Take care, Diane

  8. Sure can! Optimal pH for most plants is between 6 and 7. Generally the more acidic your soil is the more biotic matter you have in the soil up to a certain point around 4.5-5. Sugar will put your biotic matter into a feeding frenzy and over time could lower the pH in your soil.

    Dr. Watson, my old arboriculture professor said that he found this out when trying to improve tree health in higher pH soils around 7.5+ by putting sugar around the roots of the tree.

    So if your soils is lower than 7.5 pH I would look elswhere to try and find the issue. Most urban trees die from over-watering and not enough space to grow.

    Oh yea i almost forgot. Color is the easiest indicator to the amount of biotic matter in your soil if you dont have any way of testing the pH. A cool test would be to see if sugar has a greater effect on say.. a lighter color soil or how it can be effected in different types of soil like sand, silts, and clays.

    If yall have any more questions email me.

  9. Nice post, Your comments on how sugar interacts with micro biota in the soil is correct. Be wary of suggesting this method to others with a different soil type, depending on the pH of the soil and many factors will determine how well the results will be.

  10. What a pleasure to read this article. Both very informative and written with humor.

  11. Thank you for this informative and fun article. Thank you for the additional info you provided too.
    Have a great day.

  12. Tom, thanks for you kind comments, and thank you for reading and your support. I believe Mr. Watterson was trying to be helpful, and I appreciate feedback that can be constructive. Best of luck with your gardening adventures! Diane

  13. Don’t let Alan Watterson rain on your parade. I appreciate the article and Alan’s comments as well, despite his overall critical tone.

  14. Hi Alan, thank you for reading my blog, and thank you for commenting. I probably should have gone into a little more detail. Originally Epsom salts were harvested from boiling down water from the salty springs of that name. Now they process the salts from dolomite (the term ‘manufacture’ is used improperly here – my bad). The result is a powder which they make into a crystalline form that is anhydrous, which lacks moisture and thus is more easily measured (less irregular weight). The instructions I linked to were how to turn the powdered, hydrous form into the crystalline, anhydrous form. Yes, I see where I capitalized magnesium a couple of times. That comes from blogging around midnight and not proofing well enough. Since that blogpost was written (almost two years ago) soil in my food forest and kitchen gardens have become microbiotically active enough that I add only compost and mulch to the surface. The Epsom salt and sugar trick is for dirt that needs a boost. Thanks again. Diane

  15. Magnesium sulfate occurs naturally as the minerals epsomite and kieserite, it is not ‘manufactured’. Also the link you have included to making Epsom salts at home is absurd. Dissolving magnesium sulfate in water and re-crystallising it does not create a new material, as you point out ‘Epsom salts is magnesium sulfate.’ Btw chemical elements aren’t capitalised.

Leave a Reply

Your email address will not be published. Required fields are marked *