In autumn, the focus on supplying the plants in the ornamental and kitchen garden is different from that during the vegetation phase. In order to equip their garden and lawn for the rigors of winter, experienced hobby gardeners now specifically buy Thomaskali. A nitrogen-rich complete fertilizer would now induce fresh plant shoots that have nothing to oppose to frosty temperatures. In winter, other nutrients are required that regulate the water balance and strengthen frost resistance. Here you can read well-founded information on the specific composition of Thomaskali, the special effects and professional use of the effective nutrient booster for the cold season.


  • Granular PK fertilizer, supplemented with magnesium and sulfur
  • Phosphor (P2O5): 8 %
  • Potassiumoxide (K2O): 15%
  • Magnesium oxide (MgO): 6 %
  • Sulfur (S): 4%
  • Nitrogen (N): 0%

This is the common formulation for the home garden. Alternative compositions are available from specialist retailers, most of which are aimed at commercial users.
The components in detail and their effect


Phosphorus is one of the main nutrients for your plants, as it has a fundamental function in the energy balance. In addition, the element is an important part of the tissue cells and contributes to their stabilization. Last but not least, as a component of DNA, phosphorus is involved in the control of all metabolic processes and the processing of genetic information. The vital element is also able to cement the soil particles, which results in excellent crumb formation in the soil. In order to counteract the winter dangers of soil silting up and erosion, phosphorus must therefore not be missing in St. Thomas’ potassium as the ideal autumn fertilizer.


In addition to nitrogen and phosphorus, potassium is one of the three main pillars in the supply of nutrients. The element plays a central role in Thomaskali, as it strengthens the cell tissue and improves gas exchange in the roots. In this way, the plants in the garden and the sensitive lawn grass are better equipped for the constant change between freezing and thawing weather. Without this strengthening, the cell walls could burst under the pressure of expansion and compression, causing the entire plant to perish. In addition, potassium helps to increase the cell sap pressure, so that the fertilized plants can cope with lower temperatures. In spring, potassium takes an active part in the nutrient balance in the formation of new leaves, shoots, flowers and fruits.


In Thomaskali, magnesium is primarily responsible for balancing the pH value in the soil so that nutrient availability is optimal. If there is a lack of magnesium in the soil, important elements are fixed in the soil and can no longer be transported into the interior of the plant via the roots. At the same time, the trace element ensures a stable energy balance and participates in the formation of protein, vitamins and carbohydrates. Last but not least, magnesium is indispensable for photosynthesis and must not be missing in the transition from winter to spring as an important building block for chlorophyll when the leaves are sprouting.


Due to the significant reduction in sulfur emissions from industry and power stations over the past 25 years, a lack of sulfur in the natural nutrient supply is increasingly observed. What acid rain did until the 1990s, now has to be added to the soil. This is why Thomaskali also contains a small amount of sulfur to compensate for leaching and to vitalize the existing soil life.
Tip: In addition to its many advantages in terms of its mode of action, the use of Thomaskali relieves the horticultural annual budget. If the one-off basic fertilization is carried out in autumn or spring with the special fertilizer, you have the free choice of the cheapest, pure nitrogen fertilizer at flexible dates in the further course of the season.


If you buy Thomaskali in the common active ingredient combination PK 8 + 15 (+6 magnesium), the prices depend on the quantity purchased. Since you can cover an area of ​​up to 100 square meters with an application rate of 5 kilograms, in the home garden you rarely come into the dimensions that lead to noticeably reduced prices. The following list provides an overview of the average price structure in the market:

  • 1 kg: 7.90 euros
  • 5 kg: 11.95 euros (corresponds to 2.39 euros per kg)
  • 10 kg: 14.95 euros (corresponds to 1.50 euros per kg)
  • 25 kg: 14.90 euros (corresponds to 0.60 euros per kg)
  • 450 kg: 394.00 euros (corresponds to 0.88 euros per kg)
  • 850 kg: 443.50 euros (corresponds to 0.52 euros per kg)

As soon as you buy larger quantities of the fertilizer, the prices per kg drop noticeably. This effect can be recognized in a striking way by the fact that the prices for 10 kg from retail and 25 kg from agricultural wholesale differ by only 5 cents. Savvy hobby gardeners therefore buy a supply for several years, provided that there is a corresponding storage room.

Recommended application rate:

In specialist shops, the recommended dosage for Thomaskali ranges from 50 to 150 grams per square meter. This broad amount of information is not very helpful when it comes to individual measurements in the bed. For your orientation we have made a more detailed breakdown:

  • Erdbeeren: 50-60 g your m²
  • Soft fruit, wine: 60-80 g per m²
  • Perennials and flowering shrubs: 80-100 g per m²
  • Meadows and lawns: 100-120 g per m²
  • Cabbage, savoy cabbage, leek: 120-150 g per m²

Tip: Chemical fertilizers are taboo in the ecologically oriented home garden. In this regard, Thomaskali is no exception. In order to still supply plants and green spaces with potassium before winter, comfrey manure for perennials and pure, untreated wood ash for fruit trees are natural and effective alternatives.

Use in the ornamental and kitchen garden

A single application of Thomaskali is enough to supply the ornamental and kitchen garden with the special combination of nutrients for a whole year. The best time is in autumn so that your plants are well positioned for the coming winter. Since autumn is planting time for both trees and shrubs, the young plants also receive an additional portion of resistance for the cold season. How to use PK fertilizer correctly:

  • Remove leaves and crop residues from the area to be fertilized
  • Weeding and raking the ground
  • Sprinkle Thomaskali in the appropriate amount and rake in about 5 cm deep
  • Never apply mineral fertilizers on dry soil or in direct sunlight
  • Avoid contact between fertilizer and green parts of the plant
  • Add in connection with the planting of the soil to be filled in and put into the planting hole
  • Pour the fertilized soil abundantly

If you missed the ideal time window from September to November, apply the fertilizer in early spring. Autumn is also the ideal date to prepare the seedbeds for the coming season with Thomaskali. In this case, spring is not a suitable alternative date, as the sensitive seedlings are not equipped for the concentrated nutrient load.

Application on the lawn

At the end of the gardening year, the autumn fertilization is part of an overall package of care measures so that a velvety green lawn carpet develops in the next year as well. The focal point is the removal of matting, moss and weeds so that the roots of the noble grasses can absorb the nutrients well. This is achieved with a scarifier that combs out the green area with rotating knives. This is how you integrate the gift of Thomaskali into the autumn care program:

  • Mow the lawn to a depth of 3-4 cm in September / October
  • Use the scarifier to work the lawn in a checkerboard pattern
  • Adjust the device so that the sward is scratched about 3 mm deep
  • Sweep the combed out moss and weeds from the green area

After this preparation, fill Thomaskali into a spreader and set the dosage to 100 to 120 grams per square meter. Please pace the area so that the strips do not overlap, which could lead to local overdosing. Finally, set up the sprinkler to thoroughly rain in the granules. Do not mow again until no fertilizer grains can be seen.

Soil analysis shows real needs

A professional soil analysis provides profound insights into what the basic nutrients in the garden soil really are. For this purpose, soil samples are taken every 3 to 5 years in order to have them examined in a special laboratory. In the ornamental and useful bed, the removal depth is 20 to 30 cm, while it is 10 cm in green areas. For a small fee, you can receive a detailed report with recommendations for supplementary nutrient intake.


By fertilizing your garden and lawn with Thomaskali in autumn, the plants and grasses are well prepared for the coming winter. The specific composition of phosphorus, potassium and magnesium strengthens the frost resistance, creates a fine crumbly soil and supports the metabolism. A single application is sufficient to guide your ornamental and useful plants through the hardships of the cold season in good health. The application rate is tailored to the type of plant. Scattered on the weed-free soil, rake in the granules about 5 cm deep and then water. Mow and scarify the lawn beforehand so that it can perfectly absorb the active ingredients.

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