The plants in the garden need nutrients. Every gardener strives to provide them with these nutrients in the optimal form and quantity. Epsom salt fertilizer can also be used in the garden. Not necessarily an easy task, as the following article shows.

Do You Really Need Epsom Salt Fertilizer?

Please do not rush into this article with the exclamation “Finally a new fertilizer!” and then onto the bed with the Epsom salt fertilizer in your hand. Because Epsom salt fertilizer as pure Epsom salt is a pure magnesium fertilizer, as Epsom salt fertilizer mixed with potash it is mainly a magnesium fertilizer, and most likely your garden soil does not need it.

media report

The Federal Environment Agency has found that many hobby gardeners have both too much nitrogen and too much magnesium in their garden soil. A study of more than 800 Bavarian house and allotment garden soils not too long ago also showed that most garden soils are very good and often oversupplied with magnesium.

However, excessive fertilizing with magnesium-containing products hinders the general growth of the plant.

The soil analysis

With any other fertilizer it is very similar to magnesium, if there are too few nutrients in the soil, you have to help. As a rule, however, there are too many nutrients in the soil of our house and allotment gardens. The statistics from the soil analysis laboratories show that most of our garden soils are over-fertilized – in some cases severely.

If you don’t join the group of around 90 percent of home gardeners who simply spread complete mineral fertilizer over their garden according to their feelings, you are not only doing the environment a favor, but also your garden soil and your plants. Properly fertilizing means, as rarely and as little as possible. Only a soil test can tell you when and how much fertilizer is needed.

So you are doing well if you make the application of your fertilizer dependent on a soil analysis. A standard soil test determines the phosphate content and potassium content in the soil as well as the pH value. If you wish, the magnesium content can also be determined as part of this examination. How muchThe amount of nitrogen in the soil cannot be determined by the standard soil test. This requires an analysis of the humus content in the soil. Here it is examined how much organic matter the soil contains. This then enables conclusions to be drawn about the nitrogen supply. All the values ​​just mentioned hardly change noticeably over longer periods of time. They only need to be checked about every five years. Your local environmental office will tell you where to find the nearest contact person for the investigations. The examinations usually cost less than 20 euros.

The results of the studies just mentioned give you all the long-term important soil values. Experience has shown that all other nutrients are sufficiently available. An investigation would therefore only cause unnecessary costs. Before each sowing or, in the case of perennial plants, in the spring, you should examine the mineral nitrogen content. A quick nitrate test is sufficient for this, which you can carry out yourself with the help of nitrate test sticks following the appropriate instructions.

A soil test is also necessary for brown leaves

When it is said that Epsom salt fertilizer helps against browning of leaves or needles, that is not true. Magnesium deficiency does not necessarily have to be responsible for this, the blue color can also be caused by a location that is too wet or a soil that is too compacted.

It is completely normal for the inner needles of coniferous wood to turn brown, as they do not get enough light. Or through drought, here a coniferous tree throws off the inner needles that are used the least. In addition, the coniferous trees will eventually shed needles that are too old from previous generations, and cypress species such as Thuja often turn brown if they get too much sun in winter at very cold temperatures, the dye serves as sun protection here.

For all these reasons for the brown leaves, Epsom salt fertilizer does not help. If you were to apply Epsom salts on suspicion, you would fertilize one-sidedly and possibly cause an oversupply of magnesium, which then leads to an undersupply of potassium.

The magnesium levels in the soil

The nutrient content determined during soil testing is given in milligrams (mg) per 100 g of soil.

The experts differentiate between six types of soil, based on the grain size proportions in the mineral content of the soil: The content of clay (soil components up to 2 microns), silt (soil components between 2 and 63 microns) and sand (soil components from 0.06 to 2 millimeters) is differentiated ).

For growing soil in agriculture, which is comparable to a garden bed, the following values ​​are considered necessary:

  • light soils of sand, loamy sand or sandy silt: optimum supply with a magnesium content of 3 to 4 mg per 100 g of soil
  • medium soils of heavy sandy loam, loamy silt, sandy loam or silty loam: 4 to 6 mg of magnesium per 100 g of soil
  • heavy soils of loam, silty clayey loam or clayey loam: content of 6 to 9 mg magnesium per 100 g soil

If these values ​​are available, the magnesium content is actually okay, only maintenance fertilization is recommended, which in the case of magnesium only replaces the leaching losses that are always present.

Instructions for the application of Epsom salt fertilizer

If the analysis shows that there is a lack of magnesium in the soil, the Epsom salt fertilizer is applied from April, and if the content is very low, it is applied again later. These amounts should be applied (the average magnesium content is the value that only requires maintenance fertilization:

1. Light soils, Epsom salt fertilizer per square meter:

magnesium content in the soilNecessary fertilizer
below 1mg/100g20 g Epsom salt 2 to 3 times a season
below 2mg/100g30 g Epsom salt
3 to 4mg/100g30 g Kalimagnesia, for rhododendrons, heather, azaleas, conifers 15 to 25 g Epsom salt
5 to 7mg/100g20 g potash magnesia, rhododendron, heather, azalea, conifers 15 – 25 g Epsom salt
over 8mg/100gno fertilization

2. Medium Soils, Epsom Salt Fertilizer Per Square Meter:

magnesium content in the soilNecessary fertilizer
below 2mg/100g30 g kieserite and 2 to 3 times 20 g Epsom salt
below 3mg/100g30 g Epsom salt
4 to 6mg/100g30 g Kalimagnesia, for rhododendrons, heather, azaleas, conifers 15 to 25 g Epsom salt
7 to 10mg/100g20 g potash magnesia, rhododendron, heather, azalea, conifers 15 – 25 g Epsom salt
over 11mg/100gno fertilization

3. Heavy Soils, Epsom Salt Fertilizer Per Square Meter:

magnesium content in the soilNecessary fertilizer
below 3mg/100g30 g kieserite and 2 to 3 times 20 g Epsom salt
4 to 5mg/100g30 g Epsom salt
6 to 9mg/100g30 g Kalimagnesia, for rhododendrons, heather, azaleas, conifers 15 to 25 g Epsom salt
10 to 14mg/100g20 g potash magnesia, rhododendron, heather, azalea, conifers 15 – 25 g Epsom salt
over 15mg/100gno fertilization

The Epsom salt is applied either immediately as a solution (2% Epsom salt, dissolves well in water) or as granules (then water well), in both cases at some distance from the plant roots and not worked into the soil – it is a Salt that would burn the roots. Epsom salt fertilizer is only topically poured or scattered at a distance and then watered in. Please do not apply Epsom salt outside of the growing season, as this would pollute the groundwater.

Use Epsom salt in combination

If your soil analysis shows that it’s missing elsewhere, Epsom salt alone won’t help you much. You would then also have to supply the other missing nutrients if you wanted to apply each fertilizer component individually, which is a huge calculation.

In this case, it is better to look for a fertilizer that contains the nutrients in the combination you need (approximate combination will do). If you can’t find it, you can also have the right fertilizer mixed for you, which is possible in many specialist gardening companies.

The prices of Epsom salts

Epsom salt is not exactly expensive to produce and therefore also quite cheap to buy, at least sometimes:

At Heinrichs Agrar GbR in 55218 Ingelheim,, where you can also register as a private customer, you can get 10 Allflor Epsom salts for €8.90, i.e. at a basic price of €0.89 per Kilogram, incl. VAT, plus shipping.

In the worst (and not likely) case you will need 40 – 60 g Epsom salts per square meter and year, i.e. 10 kg for 200 square meters of planted garden area, then this offer is just right. If you only need to feed 10 square meters of coniferous trees with maintenance fertilization, the sack would last an amazing forty years – but that doesn’t necessarily matter, because Epsom salts keep forever if stored dry (bucket with airtight lid) and the neighbors might need some Epsom salts too.

If you go to the typical home gardening store you will have to spend a little more, the regular garden center might give you e.g. B. encounter the following offer:

Gardener quality Epsom salt: 3 liters for €6.99, i.e. €2.33 per liter.

Here the Epsom salt is already dissolved and is applied in the irrigation water. Around 8 capfuls should be mixed in 10 liters of water. Now, assuming that by mixing in that 10 liters you get an Epsom salt level that meets the 2% recommendation above, you would have 200g of Epsom salts in your 10 liter bucket. According to the dealer, you should be able to fill 13.5 buckets with the 3 liters. Makes 2.7 kg of Epsom salt for around 7 euros = €2.59 per kilogram of Epsom salt.

Doesn’t sound like a great deal. It should also contain nitrogen and potassium. Quantities or percentages are nowhere to be found on the website. Targeted fertilization is therefore not possible with this product.

Which shows that with such basic supply fertilizers it is well worth taking a closer look at the price.

Simply sprinkling Epsom salts is possible, but quite pointless, similar to life without a pug (according to Loriot). Applying Epsom salts sensibly requires a soil analysis and then a few calculations – but you will then have peace and quiet and an optimally cared for garden for years.

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