pH and plants: the importance of having a correct pH

Welcome to this article. Today we're going to explain the importance of pH for your plants. Many growers try to improve the health of their plants by adding nutrients, micronutrients and so on. However, many of them overlook the importance of the pH of their water. This is a measure of how acidic or basic the water is. With a balanced pH, the plant will be able to assimilate each nutrient correctly and develop in the best possible way. An inadequate pH can lead to deficiencies.

1. What is pH?

The pH is a measure of the acidity or basicity of water. The pH scale ranges from 0 to 14. Water with a pH close to 0 is acidic, while water with a pH close to 14 is basic. This is measured by the concentration of H+ (acidic) and OH- (basic) ions in the water. Neutral water has a pH of 7.

When we talk about increasing the pH of water, we are making it more basic. Conversely, when we make it more acidic, we are talking about reducing the pH.

2. Impact on nutrient availability.

The pH influences the way in which the plant absorbs available nutrients. Plants generally prefer slightly acidic water with a pH of between 5.5 and 6.5. Some carnivorous plants, for example, prefer even more acidic water! If the pH isn't right, certain nutrients may not be absorbed, leading to deficiencies.

3. Factors influencing pH.

Several factors affect the pH of your water:

Tap water

Tap water is often basic, with a pH above 7. This is due to limescale in the pipes and minerals.

Fertilisers

Fertilisers also influence pH. The nutrients they contain can alter the pH of the water.

Rainwater

Rainwater is generally acidic, as it retains various gases linked to air pollution. Its pH can therefore vary depending on whether you live in the city or the countryside.

4. The different methods of measuring pH.

There are several methods of measuring pH, each with its own advantages and disadvantages. Some are simpler, others more economical or more accurate.

pH strips/paper:

Easy to use and economical, all you have to do is dip the strip into the water and then compare the colour obtained with a scale provided. However, this method is not very accurate.

Reagent drops:

Simply take a small amount of water, add a few drops of a reagent and compare the colour to a scale. This method is cheaper and more accurate than test strips, but less reliable than electronic devices.

Electronic pH meter:

This device measures pH quickly and accurately. It is ideal for regular monitoring, although it requires prior calibration with buffer solutions. It costs more than the other methods, but is an excellent investment for your plants.

We have a detailed article on the subject if you'd like to find out more:

https://microfluo.net/fr/blog/hardware/tout-sur-les-testeurs-ph

5. Changing the pH of your water.

Even if your water has the correct pH, adding fertiliser can change this parameter. It is therefore often necessary to adjust the pH after preparing your nutrient solution. There are several methods, some temporary and others more effective.

a. To make your water more basic :

Rudimentary method :

Baking soda: Adding 1 to 2 grams of bicarbonate per litre of water can raise the pH by 0.2 to 0.4 units.

More precise method :

Using pH-up solutions: These products are specially designed to raise the pH of the water. Dosages are indicated on the packaging and provide a reliable and long-lasting correction.

b. To make your water more acidic :

Rudimentary method :

Lemon juice: This contains citric acid, which can acidify the water. A few millilitres per litre is enough to slightly lower the pH.

More precise method:

Using pH-down solutions: This is the most common method for lowering the pH. Inexpensive, it provides a precise and stable correction over the long term.

Conclusion:

To sum up, don't overlook the importance of pH in your crop. As we have seen, a well-controlled pH is an invaluable ally in optimising the growth of your plants. By maintaining a balanced pH in your water, you can avoid deficiencies and maximise nutrient absorption.