Effects of High Electrical Conductivity (EC) on Plants

Producing high‑quality ornamental plants also depends on the ability to manage irrigation water parameters effectively, which affect substrates parameters too. Electrical conductivity (EC value) is one of the most critical factors to monitor and control.

What is EC, Electrical Conductivity

The electrical conductivity (EC) measures how well the irrigation water conducts electricity, which gets higher as salt concentration rises. That it to say that EC gives an indirect measurement of the salt dissolved in the nutritional solution by the principle that, the more salts dissolved in the water, the higher the electrical conductivity is.

Therefore, even though it’s very connected to it, EC does not correspond to water salinity, which actually quantifies the concentration of dissolved salts.

To learn more about the differences between conductivity and salinity in the irrigation water you can refer to the linked article.

What Happens to Plants When the EC Level Is Too High

Exposure of ornamental plant roots to nutrient solutions with high electrical conductivity creates an osmotic imbalance. When the EC of the solution substantially exceeds that of the root system, water uptake is inhibited: the roots are unable to draw in sufficient water, resulting in physiological water stress for the plant.

To illustrate osmotic interactions between roots and the nutrient solution, consider a container divided into two compartments by a membrane permeable to water but impermeable to dissolved salts. Initially, both sides contain the same solution at equal concentration. When salts are added to one compartment, water moves across the membrane from the less concentrated side toward the more concentrated one, in accordance with osmotic principles.

Root water uptake follows the same logic: it depends on a balanced osmotic gradient between the root system and the surrounding solution. Maintaining this balance is therefore essential, as excessive osmotic differentials can significantly limit water absorption.

How Salinity in Substrates Can Vary

Salinity should be monitored not only in irrigation water but also within the growing substrate, where it can fluctuate as a result of several factors. These include water quality, excessive fertilizer application, and reduced nutrient uptake caused by a poorly developed root system. Excess salinity can be identified by measuring the electrical conductivity of the substrate itself or by analyzing the EC of the drainage (leachate) solution. For an overview of the available methods and instruments used to assess EC and salinity in growing media, see our guide to measurement tools for substrates in ornamental horticulture.

It is also worth noting that EC and salinity do not behave uniformly across all substrates. In particular, their dynamics differ markedly between peat‑based growing media and peat‑reduced or peat‑free substrates—a topic explored in more detail in our article on how EC and Salinity behave differently in peat-based substrates in comparison to peat-reduced or peat-free ones.

Consequences of High EC Levels for Plants

The effects of high electrical conductivity in growing media cannot be generalized, as plant responses vary widely depending on species and cultivation conditions. That said, excessively high EC levels can cause damage beginning at the root zone and, in severe cases, may ultimately lead to plant death.

When nutrients are available and readily absorbed by the roots but exceed the plant’s actual requirements, phytotoxic effects may occur. Typical symptoms include leaf burn and reduced turgor, often linked to impaired water uptake. Depending on the species, these symptoms usually appear at the leaf tips or along the margins.

It should also be noted that plants can tolerate substrate EC levels above the optimal salinity range up to a certain threshold. Although such conditions may not cause visible injury, they induce physiological stress that slows growth. As a result, overall development is reduced and plants tend to remain more compact.

Conclusion

To prevent excessive increases in salinity and electrical conductivity in both the nutrient solution and the growing substrate, it is essential to select fertilizers manufactured from high‑purity raw materials and/or produced using advanced technologies. For decades, ICL has set industry benchmarks for both premium and standard water‑soluble fertilizers through its Peters and Universol product ranges.

For tailored support and region‑specific advice, please contact your local technical team via your country’s website. A direct link to the relevant regional site can be found in the top‑right corner of this page.