How to determine the pH of plants


We continue to learn a little more about pH, given how important it is. In another post we saw how to modify the pH of the soil adapting it to the crops that we could have in our garden. We usually tell you the pH needs of each plant when we talk about them, here we summarize it.


The control and regulation of soil pH is important. In some areas of the garden we will have acid, especially in the north of Spain, and in other areas, such as the south, the pH would be high or very high, with high limestone content and poor organic matter.

In these lands, the yield of acidophilic plants  will be very low, and it is necessary to make amendments of organic matter or acid elements to try to lower these values. It can be done in two ways. If you want to correct the pH of a soil to incorporate plants within that range, you can only alter the soil fraction of the plant, or, especially for extensive horticultural crops, you can correct entire hectares.

We, who are more humble, extrapolate it to the surface of a garden , where the cost to correct the soil and adapt the pH of the plants is economical.

Here we show you an image with the optimal values ​​of vegetable development with respect to pH. The darker green reflects the optimal plant pH, while the duller green shows acceptable development or one that does not pose any growth problems for the plant.

Leaving those colors will mean loss of yield of our crops.

As you can see, most of the pH values ​​of plants are between 6.5 and 7 . That is to say a bit acidic and neutral. In those values ​​we will cultivate in a totally timely manner and we will not worry any more in that regard.


Although today it is one of the least studied parameters, it is assumed that if the plant is not in its usual pH range, it may suffer from the insufficiency of a cation (elements with a positive charge) or anion (elements with a negative charge).

For which, if the pH of the plant is excessively acidic, it is assumed that it may indicate the lack of a positively charged element (calcium, magnesium, potassium, etc.). On the other hand, if the pH is alkaline or is above its usual range, some anion may be missing (nitrate, phosphorus, sulfur, etc.).

Also, although less studied still, it is said that depending on the acidity or alkalinity of the pH , above or below its usual range, the fact that it may be affected by a plague or by a disease, as such, may have more influence. We can see it in the next photo.

In the previous image we see how a pH between 6 and 7 is considered optimal and not prone to the problems described, finding the ideal in 6.4.

However, there is no direct relationship between soil pH and plant pH , but it is a factor totally dependent on the nutrients it assimilates and the transformation of salts.

Inside the plant, there must be an ionic balance , so that there is the same amount of positively charged ions (calcium, magnesium, potassium, sodium, etc.) as negatively charged (nitrogen in the form of nitrate, sulfur, phosphorus , chlorine, etc.).

The measurement of the ph of the sap can be done with a pH reader . The process will consist of squeezing a leaf or petiole to extract the cellular juice and passing it through one of these devices.

And you, on what pH do you move in your garden or orchard?

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