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Epsom Salt - A colorless, odorless, and water-soluble mineral known for a variety of uses. It is not only used in medicine and chemistry, but also in agriculture and horticulture. Many hobby gardeners now swear by the “miracle cure” Epsom salt. However, some caution is required when using it in the home garden. The desired results are not always achieved. However, when used correctly, the plants benefit from healthy growth.

Epsom salt fertilizer

The natural mineral is magnesium sulfate (MgSO4) and also known as epsomite or epsom salt. Epsom salt contains 15 percent magnesium oxide (MgO) and 30 percent sulfuric anhydride (SO3). Because of this, it is an excellent supplier of magnesium and sulfur, in short a special fertilizer for plants.

Magnesium is a building block of the vegetable pigment chlorophyll (responsible for the green of leaves). Plants need magnesium to build sugars, from which they ultimately make cellulose and other endogenous substances that are necessary for photosynthesis. Epsom salt is also an important component in various complex fertilizers, the so-called "complete fertilizers".
In agriculture and horticulture, the mineral is mainly used to compensate for magnesium deficiency in the soil. At the same time, the pH value of the soil is reduced during use. Epsom salt is used as granules, but also as a liquid fertilizer, but not all plants tolerate this fertilizer. More on that later.

notice: In addition, the salt is also successfully used in medicine, for example in "heat packs" to generate therapeutic warmth or as a laxative, for purification, for strains, sprains and arthritis.

Epsom salt for sulfur supply

Since Epsom salt also contains a very high proportion of sulphur, it is an excellent sulfur fertilizer. A lack of sulfur in the soil mainly manifests itself similar to the symptoms of a lack of nitrogen. The entire leaf, including the leaf veins, usually turns yellow. However, this usually only affects young leaves.
Regular incorporation of mature compost or rotted cattle manure can prevent a lack of sulfur in the soil in advance. In addition, however, the sulfur balance can also be balanced by the targeted administration of Epsom salt or other mineral and organic compound fertilizers.

Not all soils tolerate a dose of Epsom salt equally well. Before fertilizing with Epsom salt, the condition of the soil must be known. You can easily determine the pH yourself using a quick test. However, a detailed soil analysis should be left to a laboratory.

notice: Soil analyzes are carried out, for example, by agricultural testing and research institutes (LUFA). Information is available from local environmental agencies. Depending on the scope, the costs are between 20 and 50 euros.

soil analysis

Before fertilizing with Epsom salts, it is important to know the soil conditions. A soil analysis offers protection against over-fertilization with nutrients. Otherwise the roots can quickly burn due to an excessive salt content. Eventually the plants will dry up. A professional soil analysis provides information about

  • soil pH
  • Overview of the existing nutrients such as
    • magnesium
    • nitrogen
    • potassium
    • phosphorus
    • copper
    • iron
    • boron
  • at the same time, a fertilizer recommendation is given

Carrying out the soil analysis

At least 500 g of soil should always be taken from a uniformly used garden area, such as a vegetable garden or lawn. The more samples are available, the more reliable the result will be.

  • uniform removal of 10 to 15 samples over the entire area
  • Thoroughly mix samples in bucket
  • Pour 500 g into a plastic bag
  • provided with name, date and garden area

The correct depth from the entire root zone of the plants in question is important when removing. The nutrient deposits, which are also reached by the plant roots, are of importance.

  • Lawn at least 10 cm
  • Vegetable and perennial bed 30 cm
  • Fruit and coniferous trees maximum 60 cm

notice: A professional soil analysis provides long-term results for five years. Then it should be repeated.


Depending on the nature of the soil and the existing magnesium value per 100 g of soil, the following dosage recommendations result:

Light floors

  • Water seeps away quickly
  • Leaching of increased magnesium content
  • 30 g of salt per square meter with a magnesium value of 1 to 2 mg per 100 g of soil
  • 15 g of salt per square meter with a magnesium value of 3 to 5 mg per 100 g of soil
  • no application if the magnesium value is over 5 mg per 100 g of soil
  • Fertilize two to three times per season
  • first fertilization in June
  • Repeat in August

Medium floors

  • 30 g of fertilizer per square meter with a magnesium value of 1 to 4 mg per 100 g of soil
  • 15 to 20 g of fertilizer per square meter with a magnesium value of 5 to 10 mg per 100 g of soil
  • no dose if the magnesium value is higher than 10 mg per 100 g of soil
  • Fertilize once per season

heavy soils

  • 30 g fertilizer per square meter with a magnesium value of 1-8 mg per 100 g soil
  • 15 to 20 g of fertilizer per square meter with a magnesium value of 9 to 13 mg per 100 g of soil
  • no application if the magnesium value is over 14 mg per 100 g of soil
  • Fertilize once per season

Granules or liquid fertilizer

Epsom salt can be applied in liquid form but also as granules. A few things should be taken into account:

spray solutions

  • Use in acute magnesium deficiency
  • Dissolve 200 g of salt in 10 liters of water
  • never use in sunshine
  • then burns occur
  • do not apply before rainy periods
  • Rinse plants with a garden hose before use
  • alternatively spraying after rain
  • cloudy April days are well suited


  • time of spring
  • if necessary repeat in autumn
  • sprinkle around plants
  • not directly on roots
  • some distance from the trunk
  • then water well
  • Caution: Do not wash out the salt completely

Suitable plants

Not all plants tolerate salt fertilization equally well. Therefore, caution is always required. When used correctly, the special plant fertilizer can be of great help to the following plants:


All conifers, thujas and cypresses have a high consumption of magnesium.

  • 20 g of salt per square meter compensates for the deficit
  • Use as granules or for pouring
  • for yellow-colored needles application of 2% spray solution
  • Spray underside of needles and shoots
  • Preparation Solution Dissolve 200 g of salt in 10 liters of water

notice: If the needles are already brown, there is a potassium deficiency. Then the use of special fir fertilizer or potassium sulfate is advisable.


Many lawns are undersupplied with nutrients such as potassium or magnesium. Epsom salt fertilization can remedy this.

  • time of spring
  • Fertilization after the first lawn cut
  • 50 grams of salt per square meter
  • sprinkle well on lawn
  • then water
  • Perfect for days before rain
  • prevents weed growth

The salt is also included in lawn fertilizer mixtures.

bog plants

Rhododendron, azalea and heather love an acidic environment to grow. Salt can therefore be used if the pH of the soil is too high.

  • Dissolve 150 g of salt in 10 liters of rainwater
  • Pour soil evenly
  • support of photosynthesis
  • Stabilization of the chlorophyll content of the leaves

A solution applied to one square meter lowers the pH value by one point.

vegetable plants

Heavy consumers such as tomatoes, cucumbers, celery, beetroot or spinach have a high magnesium requirement. Deficiency symptoms can quickly occur. A targeted administration of the salt fertilizer then ensures a sufficient supply of magnesium.

  • weekly foliar fertilization
  • Use 0.5% saline solution

tip: In the case of leaf spot disease, an improvement in the symptoms can also be achieved by spraying a 2% concentration of Epsom salts. In this case, however, the administration of nitrogen-rich fertilizer must be avoided.

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