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A fresh, green lawn is the pride of every hobby gardener. In addition to water, light and nutrients, the pH value of the soil plays a fundamental role in its growth. Because the lawn is only able to absorb the nutrients provided and then integrate them into its metabolism if it is in the right pH range. Here we explain how to measure the soil pH value correctly and how it can be improved in the direction of the optimal pH range.

The ideal pH for lawns

Unfortunately, there is no one ideal pH value for lawns. Because every nutrient can be optimally accessed by the plants in a slightly different pH range. Since you cannot simply adjust the value for an individual nutrient from time to time, it is important to find an optimal medium for the different requirements. If you believe the specialist literature, the following average values are best suited to allow the lawn to grow as best as possible:

  • Light, sandy soils: 5.2 to 6.0
  • Heavy, clayey soils: 6 to a maximum of 6.5

If the soil composition is somewhere between these extremes, the pH value in the lawn should also be adjusted to an average value.

Measure pH

Reliable statements about the soil properties require a reliable and at the same time simple measuring method. Because only if the measurement results are reliably correct can conclusions be drawn about necessary measures to improve the soil. The following measuring methods are suitable for use by hobby gardeners and in connection with lawn and its growth base:

  • pH measuring strips
  • Test kits with reagents
  • soil analysis
  • Measuring devices (so-called pH meters)
  • pointer plants


pH measuring strips are pre-treated paper strips that indicate the pH value of an aqueous solution. To determine the soil value, a soil sample is mixed with distilled water and the strip is adjusted. The exact pH value can be read from a comparative scale based on the discoloration of the strip.

test sets

Similar to test strips, test kits work with reagents. According to the instructions, a soil sample is prepared with pure water and then a test tablet is added. The developing color of the solution indicates the pH of the soil.

soil analysis

The most complex, but also the most accurate, is the preparation of a soil analysis by a laboratory. For this purpose, a soil sample is taken and sent for analysis. In addition to the pH value, all other essential factors of a cultivated soil are also determined, such as the nutrient content.

Measurements about electrical devices

So-called pH meters determine the soil acid via the electrical conductivity of an aqueous solution created from a soil sample. High-performance measuring devices are very expensive, however, and are mainly available in laboratory supplies. The simpler the pH meter, the more imprecise the results are usually.

danger: Again and again one reads about very inexpensive multiple measuring devices, which determine not only the soil acidity but also the brightness of the light, the temperature and the humidity. Be expressly warned against these devices. Usually, these are cheap products from the Far East, which do not reliably determine any of the supposedly determinable values and mislead the hobby gardener in his concern for the lawn instead of supporting him.

pointer plants

So-called indicator plants are a natural alternative for roughly determining soil acidity. Depending on the pH value, certain types of plants settle preferentially and thus indicate the approximate acidity or alkalinity. Of course, they do not replace the effort of taking additional measurements for an exact determination. Well-known and easily recognizable indicator plants are:

For acidic soils

  • sorrel
  • pansies
  • wood sorrel
  • horsetail

For alkaline soils

  • dandelion
  • bindweed
  • pasque flower
  • nettle
  • poppy
  • coltsfoot
Chilean Wood Sorrel, Oxalis valdiviensis

improve pH

If one has come to the conclusion that the soil value for the lawn cultivation is not in the optimal range, there are two possibilities. If the value is too high, it is too alkaline. In this case it should be reduced by adding acid. On the other hand, if the value is too low, it means the soil is too acidic. In this case, the value must be increased by adding alkaline substances. But how can the pH value be adjusted in practice and which substances are suitable for improving the soil?

pH lowering

Ultimately, to lower a value that is too high, you have to add acid to the soil. This works best if soil-like substances with naturally high acidity are incorporated into the soil:

  • peat
  • Oak barrel compost
  • Coniferous soil (the soil from the immediate vicinity of conifers)
  • Iron sulphate (salt of sulfuric acid)
  • Grape pomace (solid residue from the pressing of grapes in juice or wine production)
  • Softwood and oak leaf mulch layer
  • Sulfur (especially in heavily compacted soils)
  • Rainwater (for irrigation instead of tap water)

increase in pH

On the other hand, if the lawn is too acidic, the pH value needs to be raised. Contrary to the quite extensive list of common additions to reduce the value, only very few substances are used to increase it:

  • Potassium hydroxide (caustic potash)
  • potassium carbonate
  • soda
  • Ground Lime

No matter which substance you choose to improve the soil, it would be optimal to incorporate it before sowing the lawn. The additives can then be spread over the soil and simply worked into the top layer of soil with a hoe, digging fork or motor hoe. However, it will often be the case that after sowing you will notice that the little plants are not developing properly or that an existing lawn is becoming ugly and no longer thrives. In these cases, the aggregates should be distributed evenly over the lawn and incorporated only moderately. A good option is to combine the whole thing with spring mulching and use the loosening of the root system to work in compost, sulphur, lime etc. at the same time. However, it should not be worked in too intensively, otherwise damage to the plants can occur, which can also have a negative effect on the soil balance.

tip: If the lawn already exists, it can make sense to resort to the "chemical" variants of soil improvement, i.e. sulfur, iron sulphate, etc. These substances are in powder form and can therefore be easily spread on the lawn. Just by watering or raining, they are well washed into the soil and can work there without additional effort.

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