Whether a plant thrives or not depends primarily on care. The soil conditions in particular play a major role here, as they determine how well or poorly the plants are cared for. Fertilizer is a common tool to improve soil. Epsom salt fertilizer is increasingly being discussed. Which plants tolerate it and how the application works can be read below.
Table of Contents
What is Epsom salt?
Epsom salt is a mineral that can be found in around 60 salt deposits in Germany. It consists of pure magnesium sulphate, is odorless and water-soluble. Epsom salt is mainly known from human medicine.
effect
Magnesium is one of the most important components of green plants. It makes an enormous contribution to the formation of green leaves and is essential for photosynthesis. In addition, the pH value in the soil can be lowered with an Epsom salt fertilizer and in this way ensure more balanced soil values if necessary. It also reduces the potassium in the soil.
mission
It is used when there is a higher need for magnesium in green plants or when there is a magnesium deficiency. If they lack magnesium, leaves and needles will turn yellow or brown and die if left unchecked. By using Epsom salt fertilizer, plants receive an extra portion of magnesium sulphate to prevent deficiency symptoms or to remedy an existing deficiency in the soil.
compatibility
In any case, caution is advised when using it, because not all green plants have a high magnesium requirement, which can be covered by Epsom salt fertilization. Sometimes yellow leaves are also a reaction to the soil pH being too low. Giving magnesium sulfate through Epsom salts would only worsen the condition further through the pH-lowering effect. In conifers, brown needles can also indicate a potassium deficiency. It is therefore advisable to carry out a soil analysis before each application and to limit the application to green plants that can tolerate an extra portion of magnesium sulphate.
Soil analysis before application
Special test sets for soil analysis can be purchased from well-stocked specialist shops. Rapid tests provide immediate results. The optimal nutrient content or the values of magnesium sulphate depend above all on the respective soil conditions. The following values apply as a guideline:
- Light soil with a small amount of sand and/or clay: three to four milligrams of magnesium per 100 grams of soil
- Medium soil with lots of sand and/or clay: four to six milligrams of magnesium per 100 grams of soil
- Heavy soil with a high proportion of clay: six to nine milligrams of magnesium per 100 grams of soil
dosage
If the test results in lower values, these should be optimized with the help of the Epsom salt fertilizer. Hobby gardeners are well advised to use the following general dosage recommendation, although there may be deviations depending on the plant to be fertilized, as can be read below under “Plants compatible with Epsom salt fertilizer”.
Light soil
- Magnesium value is between one and two milligrams: Fertilize 30 grams of Epsom salt per square meter
- Mg value is between three and five milligrams: Fertilize 15 grams of Epsom salt per square meter
- Mg value is six or more milligrams: no Epsom salt fertilization
middle bottom
- Magnesium value is between one and four milligrams: Fertilize 30 grams of Epsom salt per square meter
- Mg value is between five and ten milligrams: Fertilize 15 to 20 grams of Epsom salt per square meter
- Mg value is eleven or more milligrams: no Epsom salt fertilization
heavy soil
- Magnesium value is between one and eight milligrams: Fertilize 30 grams of Epsom salt per square meter
- Mg value is between nine and 13 milligrams: fertilize 15 to 20 grams of Epsom salt per square meter
- Mg value is fourteen or more milligrams: no Epsom salt fertilization
Exception: If very old or enormously tall conifers are to be fertilized with Epsom salt, a double or triple dosage is recommended, because they need a significantly higher magnesium requirement for a proper supply.
administration
It is available in granular form and as a liquid Epsom salt fertilizer for use on green plants. The granules can be applied directly to the floor. Epsom salt as a liquid fertilizer is ideal as a “first aid measure” if there is an acute magnesium deficiency and rapid action is required. When administering, some details and tips should be observed:
- Water the plant before fertilizing
- In acute cases, spray liquid fertilizer on needles/leaves (wash them off with water beforehand)
- Do not spray in direct sunlight (risk of burns)
- Application during a rain saves the previous watering/moistening
- Granules are good for preventing magnesium deficiency
- Best time for prophylactic fertilizer application: spring – autumn second fertilization possible
- Do not apply Epsom salt granules directly to roots
- Granules dissolve better/faster if watered after administration
- Always wear gloves when applying Epsom salts
Epsom salt fertilizer compatible plants
Boxwood (Buxus)
Boxwood has a moderately high magnesium requirement. If there is no regular fertilization with trace elements, a magnesium deficiency will eventually become noticeable with yellowing of the leaves (usually older foliage first). The magnesium content in the soil can be regulated by immediately fertilizing with 50 milligrams per square meter of Epsom salt. As a result, the boxwood recovers quickly. In future, Epsom salt fertilization is recommended in spring and, if necessary, in autumn, as described under “Dosage”. Very large and old box trees can be fertilized three times a year at 30 grams of Epsom salt per square meter, because the need is much higher than for smaller, young specimens.
Hydrangea (Hydrangea)
Hydrangeas in particular tolerate Epsom salt fertilization well. Since they like acidic soil below a pH of 7.0, there is nothing to stop them fertilizing with magnesium sulfate.
Kirschlorbeer (Prunus laurocerasus)
If the leaves of a variety with dark green foliage suddenly turn light green, this is often a sign of a magnesium/iron deficiency. This can be counteracted with an Epsom salt fertilizer. The cherry laurel copes well with the influence of the fertilizer on the pH value, as this can easily drop to 5.0. Only the potassium content should not be ignored and, if necessary, potassium sulphate should be fertilized at a later date. Incidentally, Epsom salt sprayed on the plant as a foliar fertilizer ensures more leaf shine.
Koniferen (Pinales)
All conifers are among the plants with the highest magnesium requirement because they consume a correspondingly large amount. The best-known and most widespread conifers include cypresses (Cupressus) and arborvitae (Thuja). If there is a lack of this trace element, this quickly manifests itself with yellow discoloration of leaves or needles and usually with stunted growth. Epsom salt fertilizer can usually be applied here without soil analysis. There is nothing wrong with doing it. Especially with conifers, brown discoloration of the needles and foliage is usually due to a potassium deficiency. If Epsom salts were now administered, this would further increase the deficiency. Therefore, do without it here and instead administer a fertilizer especially for firs/conifers with multiple nutrients.
fruit and vegetable plants
Sweet fruits and vegetables in particular lose their sweetness when a magnesium deficiency spreads, but the acidity increases. Splashing with Epsom salt prevents this and at the same time makes the fruit shine more. The application is simple: just prepare a 4-6% solution every two weeks from the beginning of fruit formation and lightly wet the leaves and fruit. If there is a magnesium deficiency in vegetables, a two percent solution is sufficient. This fertilization is particularly suitable for:
- strawberries
- blueberries
- apple trees
- pear trees
- Cherry trees
- tomatoes
- Parsely
- cucumbers
- Beetroot
- Saddlery
lawn
If the lawn yellows , there may be a magnesium deficiency behind it. Incidentally, according to the North Rhine-Westphalia Chamber of Agriculture, 75 percent of lawns suffer from a magnesium deficiency. However, pure Epsom salt fertilization would block iron absorption. This must be compensated for by additional fertilization of nitrogen, phosphorus and potassium. The ratio should look like this:
- Ten parts nitrogen
- Six parts of phosphorus
- Ten parts potassium
- Four parts Epsom salt
Rhododendron (Rhododendron)
The rhododendron reacts particularly sensitively as soon as the pH value of the soil is not acidic enough. With a recommended pH value of around 4.5, this is significantly lower than most other plants tolerate and normal garden soil usually has. Here Epsom salt fertilizer can provide the ideal remedy and optimize the pH value. However, to lower the pH by one point per square meter, magnesium sulphate is prepared and applied as follows:
- Pour ten liters of water into the watering vessel (use lime-free water)
- Add 150 grams of Epsom salt and stir until dissolved
- Slightly loosen the soil to be fertilized
- Make sure no roots are exposed
- Pour fertilizer slowly over the area
- If you water too quickly, too much fertilizer could flow out of the fertilizing area due to water congestion
Roses (Pink)
Roses have some leeway when it comes to soil pH, which can go as low as 5.5. Magnesium is one of their most important nutrients. A deficiency disrupts the absorption of moisture and other important nutrients such as nitrogen and phosphorus. A deficiency usually manifests itself in the form of stunted growth, initially yellow spots on the leaves and later complete yellowing and browning of the inner leaf area. Leaf edges usually remain unaffected. Fertilization is recommended annually in spring, while potassium should be administered in autumn because it improves frost hardiness and has a positive effect on bud formation and flower color in the following year.
