The Power of Iron in Hydroponics

Although iron is needed in smaller quantities than macronutrients, it plays an outsized role in chlorophyll production, photosynthesis, and crop quality. Ignoring it could cost you yield, especially in high-value or weight-based crops.

Why Iron Matters in Hydroponics

Iron is a central component in the production of chlorophyll, the pigment responsible for photosynthesis. While magnesium is at the center of the chlorophyll molecule, it’s iron atoms that support its structure and function.

Without iron:

• Chlorophyll production halts
• Photosynthesis is impaired
• Plants show signs of chlorosis, especially in young leaves

In other words, iron deficiency literally starves your plants of light energy.

Symptoms of Iron Deficiency in Plants

🌱 Chlorosis of Young Leaves

Iron deficiency usually shows up first as interveinal chlorosis (yellowing between veins) in new growth, because iron is not mobile in the plant. If left untreated, it can spread to older leaves.

This issue is especially common in:

• Citrus plants
• Houseplants
• Crops grown in alkaline soils

Why Iron Becomes Unavailable in High pH

Iron availability is extremely sensitive to pH levels. As pH rises:

• Iron becomes 100x less available for each unit increase
• Other micronutrients like copper only become 10x less available

That’s a massive drop. So in alkaline soils or media, you must compensate using chelated iron (Fe-EDDHA, Fe-DTPA, etc.).

Fast Green-Up? Not Always What It Seems

Iron is commonly used in lawn care and sports turf due to its rapid green-up effect. However, this isn’t chlorophyll production—it’s iron binding to tannins in cell walls, giving an instant dark green appearance.

In crops like citrus or hydroponics true chlorophyll production takes weeks.

Iron in Gold Leaf: Why the Color Matters

Here’s a fun fact: Gold Leaf (aka Liquid Gold in the UK) is gold in colour because of its iron content. Many one-part fertilisers claim to be complete, but if they’re clear or white, they likely contain no iron at all.

Gold Leaf is:

• Fully soluble
• Iron-rich
• Compatible with calcium and phosphorus (which usually precipitate with iron)

Most competitors can’t achieve this balance. They either skip the iron or end up with a sludgy mess of calcium phosphate.

Advanced Growing Tip: Use Iron to Boost Crop Weight

When growers transition to flowering, most reach for PK additives. Dr. Sharp recommends something different:

“If I was going into flowering, I’d be adding iron all day, every day, and twice on Sundays.”

Why? Because iron increases cell density and weight. If you’re selling crops based on weight, iron is your secret weapon for:

• Increased density
• Improved structure
• Higher-value yields

How to Use Iron in Hydroponics

Key Takeaways:

• Monitor and adjust pH regularly
• Use chelated iron in high pH environments
• Add iron supplements during critical growth phases
• Choose a nutrient blend that already contains bioavailable iron, like Gold Leaf

If you’re an advanced grower, consider dedicated iron additives to maximize yield.

Final Thoughts: Iron Isn’t Optional—It’s Foundational

Whether you’re growing citrus, hydro crops, or managing a lawn, iron is a non-negotiable micronutrient. From chlorophyll synthesis to visual health and weight gain in crops, it plays an essential role in plant success.

Don’t overlook it—optimize it.

Article by Dr Russell Sharp

If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:

Hydroponics Daily Podcast: https://open.spotify.com/show/207T7p7fw9sPjINfSjVXW2

Cereal Killers Podcast: https://t.co/eSEbBkTVHl