The Role of Zinc in Hydroponics

Let’s explore what zinc does, when deficiencies might occur, and why using a balanced hydroponic nutrient mix usually keeps this element in check.

What Does Zinc Do in Plants?

Zinc is essential for the synthesis and function of auxin, a plant hormone responsible for:

• Apical dominance (growth direction and structure)
• Root development
• Overall plant architecture

Auxin helps determine whether a plant grows as a single-stemmed tree or a bushy shrub. It also plays a vital role in rooting, which is why auxin forms the basis of many rooting powders.

Zinc also functions as a co-factor in enzymatic activity, supporting energy transfer and metabolic efficiency.

Zinc Deficiency: Rare But Possible

While zinc deficiency is rare in hydroponics—especially when using a quality nutrient mix—it’s not impossible. Signs may include:

• Interveinal chlorosis (yellowing between leaf veins)
• Grey or brown leaf spots (though this could also be a disease)
• Distorted or stunted growth

“If I saw grey-brown spots, I’d think disease—not zinc deficiency—unless I was using a poor-quality fertiliser.” – Dr. Sharp

Most reputable hydroponic nutrient solutions include chelated zinc, making it readily available to plants even in varied pH environments.

When Is Deficiency More Likely?

You’re most likely to encounter a zinc deficiency if:

• You’re using incomplete or soil-based fertilisers in a hydroponic system
• Your soil or media pH is extremely high
• You’re growing in very low-zinc environments

High pH levels can reduce zinc availability—but you’ll typically see iron deficiency first under such conditions.

A Fun Fact: Galvanized Posts and Orchids

Zinc isn’t just found in nutrients—it’s used in galvanized steel, which contains high levels of zinc. Interestingly, some rare orchids naturally grow near galvanized posts because they are zinc hyperaccumulators.

People often wonder why rare plants seem to be growing next to fences—it’s because the zinc from the metal has leached into the soil, creating an ideal microenvironment for these unique species.

Do You Need to Worry About Zinc?

In most hydroponic setups: no.

If you’re using a well-formulated, chelated micronutrient blend like Gold Leaf (or Liquid Gold in the UK), you’re unlikely to see zinc deficiencies. It’s only when you cut corners with your fertiliser or ignore extreme pH issues that zinc might become a problem.

Final Thoughts: Zinc Is Small But Mighty

Zinc might be one of the lesser-discussed micronutrients in hydroponics, but its role in rooting, hormone regulation, and enzyme activation makes it essential for healthy plant growth.

It may not be top of mind like nitrogen or iron, but your plants notice when it’s missing.

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