How pH affects fertiliser uptake: a guide to healthy plants
A healthy garden or successful indoor cultivation begins with a basic understanding of soil and nutrient dynamics. The pH value plays a crucial role in this. It is far more than just a number – it determines how effectively plants can absorb the nutrients provided. In this blog, we explain how the pH value influences fertiliser uptake and how you can ensure that your plants are optimally supplied.
What is the pH value?
The pH value indicates how acidic or alkaline a medium is – be it soil, hydroponic water or coco substrate. The value ranges from 0 to 14:
- pH 0-6.9: Acidic
- pH 7: neutral
- pH 7.1-14: Alkaline
Plants generally prefer a slightly acidic to neutral range. However, the ideal pH value varies depending on the plant type and cultivation method:
- Soil: 6.0-7.0
- Hydroponics: 5.5-6.5
- Coco: 5.8-6.2
Why is the pH value so important?
The pH value influences how well plants can absorb the nutrients from the fertiliser. Even if you use high-quality fertilisers, your plants may show nutrient deficiencies if the pH value is not right. This is because the availability of nutrients is strongly dependent on the pH value.
How the pH value influences the availability of nutrients
Every plant needs essential nutrients such as nitrogen (N), phosphorus (P), potassium (K) and micronutrients such as iron, manganese and zinc. The pH value determines whether these nutrients are dissolved in the substrate and accessible to the roots:
- Acidic pH (span, <.5): Many micronutrients such as iron and manganese are over-available, which can lead to toxicity. At the same time, macronutrients such as phosphorus are less easily absorbed.
- Neutral to slightly acidic pH (5.5-7.0): Optimum availability of most nutrients. This range is ideal for most plants.
- Alkaline pH (span, >7.5): Micronutrients such as iron and zinc are insufficiently absorbed, which can lead to deficiency symptoms such as chlorosis (yellow leaves).
Nutrient blockages with the wrong pH value
An unbalanced pH value can cause so-called nutrient blockages. Although the nutrients are present in the substrate, they are not available to the plant. For example:
- Acidic soil: lack of calcium, magnesium and phosphorus.
- Alkaline soil: lack of iron, copper and zinc.
How do you measure and correct the pH value?
1. measure the pH value:
- Soil: Use a pH meter or test strips. Mix a soil sample with distilled water and measure.
- Hydroponics/coco: Use a digital pH meter for precision.
2. adjust the pH value:
- Too acidic? Add lime (e.g. garden lime or dolomite lime) to increase the pH value.
- Too alkaline? Use acidic substances such as sulphur, acetic acid or special pH down solutions.
- Hydroponics: Use pH up or pH down products that have been specially developed for these systems.
3. check regularly:
The pH value can change due to irrigation, fertilisation or biological processes in the substrate. Regular measurements ensure that your plants remain in the optimum range.
The pH value as the key to healthy plants
The pH value is an often underestimated factor that directly influences how effectively your plants can absorb nutrients from the fertiliser. By regularly measuring and adjusting the pH value, you can avoid deficiencies and blockages and create optimal growing conditions. Whether for your garden or indoor cultivation – a balanced pH value is the key to strong, healthy plants.
Are you looking for the best products for pH regulation?
Check out our shop and find pH meters, pH up and pH down products and everything you need for perfect growing conditions!
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