Page 27 - Griffin Gazette - March 2026

Micronutrients are required in small quantities, but their CHOOSING THE RIGHT IRON CHELATE BASED ON PH
availability plays a critical role in plant growth and crop Not all iron chelates perform equally. Chelate stability —
quality. Choosing the micronutrient form — particularly and therefore iron availability — is strongly influenced by
sulphates versus chelates — can significantly affect root-zone pH.
nutrient solubility, compatibility in nutrient solutions, and
plant uptake.
CHOOSING THE RIGHT IRON CHELATE BASED ON PH
This article provides an overview of chelated micronutrients,
Iron Chelate Relative pH Typical Use
explains why chelates are often preferred over sulphate Stability
forms, and highlights the potential risks associated with Fe-Edta Lowest Stable Between pH
mixing sulphate and chelated micronutrients, with a 1.5 - 6.5
particular focus on iron. Fe-Dtpa Moderate Stable Between pH
1.5 - 7
WHAT ARE CHELATED MICRONUTRIENTS? Fe-Eddha High Stable Between pH
Chelated micronutrients consist of a micronutrient ion 3.5 - 10
bound to an organic molecule known as a chelator. This
chelating agent surrounds the micronutrient in a stable
structure that protects it from reacting with other ions in the
growing medium or nutrient solution.
This protection prevents micronutrients from precipitating,
oxidizing, or becoming immobilized — reactions that can
occur when micronutrients are supplied in non-chelated
forms. Chelation improves the stability and plant availability
of micronutrients such as iron (Fe), manganese (Mn), zinc
(Zn), and copper (Cu).

WHY CHELATED MICRONUTRIENTS ARE MORE
AVAILABLE THAN SULPHATES
Sulphate micronutrients dissolve in water but exist as free
metal ions once in solution. These ions can readily react
with phosphates, carbonates, or hydroxides, forming
insoluble compounds that plants cannot absorb. These
reactions become more common as pH increases,
particularly above pH 6.0–6.5.

Chelated micronutrients remain protected from these
reactions. The chelating agent keeps the micronutrient
PLANTEX® IRON CHELATES: A SOLUTION FOR
soluble and available across a wider pH range maintaining
GREENHOUSE GROWERS
consistent nutrient availability.
®
For greenhouse growers, incorporating Plantex Iron
IRON: THE MOST COMMONLY CHELATED Chelates into their nutrient program ensures the availability
MICRONUTRIENT of iron, even in challenging soil conditions.
Iron is the micronutrient most frequently supplied in Plantex Iron 11% DTPA is ideal for a pH up to 7, ensuring
®
chelated form because it is highly sensitive to pH and that iron remains in a soluble, plant-available form
oxidation. As pH increases, iron readily converts into forms preventing and correcting deficiencies under mildly acidic
that are poorly available to plants, leading to deficiency to slightly alkaline conditions.
symptoms even when total iron levels appear sufficient.
®
Plantex Iron 6% EDDHA is top choice for high pH
Chelated iron protects iron from oxidation and precipitation, situations. Featuring a strong ortho-ortho isomer, it
making it beneficial for greenhouse production, hydroponic provides exceptional stability up to pH 10, ensuring reliable
systems, and high-pH media. iron availability where uptake would typically be limited.

GRIFFIN GAZETTE 20 26 | 27