Copper in Hydroponics: Essential Micronutrient or Hidden Hazard?

Copper (Cu) is essential for plant health, but it’s also one of the easiest nutrients to misuse. Let’s break down its role, when it becomes a problem, and how to keep your hydroponic system copper-balanced.

What Does Copper Do in Plants?

Copper is a vital micronutrient involved in three major functions:

🌿 1. Photosynthesis

Copper is required for electron transport during photosynthesis. Without it, plants can’t convert sunlight into usable energy efficiently.

🌱 2. Lignin Formation

Copper supports the production of lignin, a key structural compound in woody tissues and perennial crops.

⚙️ 3. Enzyme Activation

Copper acts as a cofactor in enzymes, meaning it helps enzymes transfer energy and perform biochemical tasks in the plant.

Is Copper Deficiency Common in Hydroponics?

No—true copper deficiency is extremely rare in hydroponics when you’re using a high-quality nutrient mix. Most balanced fertilisers include chelated copper in trace amounts, which is more than sufficient.

“If you’ve got a decent fertiliser like Gold Leaf or Liquid Gold, copper won’t be a problem.” — Dr. Sharp

Deficiency symptoms may include:

• Stunted growth
• Pale leaves
• Poor lignification (weak stems)

But realistically, if your pH and nutrition are balanced, you’ll see iron deficiency long before copper becomes an issue.

When Does Copper Become Unavailable?

Copper can fall out of solution when:

• pH is too high
• You’re using non-chelated sources like copper sulfate

Chelated copper (common in modern fertilisers) remains available even under suboptimal pH, making it the preferred option for hydroponic growers.

The Bigger Problem: Copper Toxicity in Horticulture

While deficiency is rare, excess copper is a growing issue—especially in soil-based horticulture. That’s because:

• Copper is widely used as a fungicide in crops like grapes.
• It’s sometimes applied under the guise of a fertiliser, but the real goal is fungicidal action.
• It’s a heavy metal that doesn’t break down and accumulates in the soil.

“Copper fungicides are toxic—not just to pathogens but to beneficial soil microbes, insects, and humans.” — Dr. Sharp

Why You Should Avoid Copper-Based Fungicides

Popular copper products like Bordeaux mixture have been banned in several countries (including the UK) due to:

• Environmental toxicity
• Soil degradation
• Microbial imbalance
• Nutrient interference (excess copper blocks absorption of other nutrients)

Alternatives to Copper Fungicides:

• Kytosan-based products
• Biological fungicides
• Improved crop management practices

Final Thoughts: Balance Is Everything

Copper is a necessary micronutrient in hydroponics, but like many things in life, too much of it can be dangerous. Stick to chelates, avoid copper-based fungicides, and use a balanced nutrient like Liquid Gold to ensure optimal plant health without unnecessary risks.

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