Haven't searched the forums for any info on this topic but was just wondering what the opinions are regarding this subject. I have used Epsom salts (magnesium sulfate) in the past with no measurable effects, good or bad, in my garden with standard vegetables like peppers, tomatoes, squash, cucumbers, okra, etc. The intent was to provide some magnesium, which is a necessary micronutrient along with calcium and sulfer, to assist the plants in being healthier and having a better overall harvest.
Recently I've been made aware that this may not be necessary and indeed, may be detrimental to my stated goals for my garden. For one I've been reading that magnesium can actually set up a calcium deficiency by out competing calcium for uptake in plants when provided in greater quantities. Also, it may be quite rare to actually have a magnesium deficiency in most garden soils, especially created soils for containers and raised beds.
Anyway, just trying to learn all that I can about proper methods to create the healthiest and most productive garden that I can, which starts with knowledge! I could surely benefit from the knowledge of fellow members regarding this topic. Thanks for the time and effort to get me up to speed!
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catdaddy66
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applestar
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I haven’t researched recently, but my understanding has always been that magnesium is easily leached away and deficiency in soil is quite common. It’s an important mineral nutrient for root growths and cell structure for fruiting crops.
Still, Magnesium Sulfate — MgSO4 — epsom salts is a salt and I use regularly but sparingly, although some gardeners swear by “1 Tbs per tomato plant, well worked in the hole at time of planting” …for example.
Instead, I usually add to water seedlings, and to supplement liquid fertilizers… then I use epsom salts for slug control (rather than table salt).
Sulfur is also a less mentioned and easily overlooked nutrient, especially when not regularly used due to already acidic soil, etc. Crucifers and Alliums are examples needing good sulfur access. When you think about it, tomatoes and peppers are originally from volcanically active regions, good farming/agricultural regions occur in volcanically active areas where micro amounts of sulfur are present in air and ash fall, etc.
Micro-amounts of varieties of minerals often from deep soil levels are useful supplementation for growth and nutrient value of crops. Some good and reliable comprehensive sources include dolomitic lime, crushed granite, azomite, greensand, and kelp.
Still, Magnesium Sulfate — MgSO4 — epsom salts is a salt and I use regularly but sparingly, although some gardeners swear by “1 Tbs per tomato plant, well worked in the hole at time of planting” …for example.
Instead, I usually add to water seedlings, and to supplement liquid fertilizers… then I use epsom salts for slug control (rather than table salt).
Sulfur is also a less mentioned and easily overlooked nutrient, especially when not regularly used due to already acidic soil, etc. Crucifers and Alliums are examples needing good sulfur access. When you think about it, tomatoes and peppers are originally from volcanically active regions, good farming/agricultural regions occur in volcanically active areas where micro amounts of sulfur are present in air and ash fall, etc.
Micro-amounts of varieties of minerals often from deep soil levels are useful supplementation for growth and nutrient value of crops. Some good and reliable comprehensive sources include dolomitic lime, crushed granite, azomite, greensand, and kelp.
A good soil test from a professional lab will tell gardeners whether magnesium sulfate is necessary to amend the soil. Small amounts of many chemicals probably will not make a difference one way or the other, but why put something into or onto the garden if it is not needed. If adding epsom salts make a gardener feel better maybe it wouldn't hurt.
My soil needs a regular feeding of sulphur for pH adjustment and a yearly dose of nitrogen is applied over the entire garden, but only as the soil test results dictate. I treat the entire garden rather than just the planting hole.
As stated, epsom salts is a salt and most gardens do not need either magnesium or sulphates. A good soil test will tell the gardener if these are needed. As for me, when a vegetable is planted the only thing going into the hole or furrow or hill or what ever is the plant or seed, the soil and a little water.
My soil needs a regular feeding of sulphur for pH adjustment and a yearly dose of nitrogen is applied over the entire garden, but only as the soil test results dictate. I treat the entire garden rather than just the planting hole.
As stated, epsom salts is a salt and most gardens do not need either magnesium or sulphates. A good soil test will tell the gardener if these are needed. As for me, when a vegetable is planted the only thing going into the hole or furrow or hill or what ever is the plant or seed, the soil and a little water.
I do what Paul does. My fertilizer contains micro nutrients, so it contains a little bit of magnesium as well. I do soil tests but I don't include the micros because I rarely ever see deficiencies in my plants except for tomato seedlings I keep too long in the pot, they start showing phosphorus deficiency. and the only other deficiency I had was a nigtrogen deficiency of the native gardenia which was fixed with MG., so now I feed it more regularly. Natives are fussy about fertilizer, so it is better to go light and a diluted MG water soluble is a good way to quickly diagnose and fix a nutrient problem. I rarely add additional calcium or magnesium to my tomato containers. The starter food is complete with micros. They get an extra tablespoon once a month.
I do get nitrogen deficiencies in plants I start organically. I have to fertilize them sooner and more often with fish emulsion, so I prefer to direct seed them rather than start them in small pots.
Now, if you are using compost or organic fertilizers, it depends on the source materials. You may have to add additional things because the organic fertilizers are not always complete, and in my case it is hard to find organic fertilizers of single elements, like fast nitrogen. Often they contain things I don't want like phosphorus and undecomposed matter that steals nutrients from plants unless you have the time to put them in 6 months before you plant.
I do get nitrogen deficiencies in plants I start organically. I have to fertilize them sooner and more often with fish emulsion, so I prefer to direct seed them rather than start them in small pots.
Now, if you are using compost or organic fertilizers, it depends on the source materials. You may have to add additional things because the organic fertilizers are not always complete, and in my case it is hard to find organic fertilizers of single elements, like fast nitrogen. Often they contain things I don't want like phosphorus and undecomposed matter that steals nutrients from plants unless you have the time to put them in 6 months before you plant.
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pepperhead212
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I agree with Paul - first, get a soil test, as you may have plenty of it in the soil. The 3 sections I test all have large amounts of magnesium in them, and they do not recommend adding any. I put a small amount in SIPs, but the organic ferts I use in those have some, so I don't add much - only 1/2 tsp/tub every few weeks.
My last soil test was done in March 2021. I have only added nitrogen for the most part for the last 10 years, and compost or bagged soil (4 inches a year.) for the last 4 years. My test includes pH, P, K, Ca, and Mg. It cost $12 from the UH extension service. The magnesium was 796 ppm, the normal levels for my soil is 300-400 ppm. I don't need to add any more. And I should probably back off on the compost and bagged soil too.
The links below are to sites that have analyzed compost in their area and found that there can be such a thing as adding too much compost and organic fertilizer which can lead to negative consequences. If you are adding compost or other fertilizers organic or synthetic, you may already have more than you need.
https://calrecycle.ca.gov/organics/farming/analyses/
https://extension.umn.edu/nutrient-mana ... and-manure
https://today.oregonstate.edu/news/stud ... nic-matter
The links below are to sites that have analyzed compost in their area and found that there can be such a thing as adding too much compost and organic fertilizer which can lead to negative consequences. If you are adding compost or other fertilizers organic or synthetic, you may already have more than you need.
https://calrecycle.ca.gov/organics/farming/analyses/
https://extension.umn.edu/nutrient-mana ... and-manure
https://today.oregonstate.edu/news/stud ... nic-matter