Molybdenum in Hydroponics

Although required in tiny amounts, molybdenum (Mo) plays a critical role in nitrogen metabolism and enzyme function. Without it, plants can’t efficiently utilize the nitrogen they absorb—a cornerstone of healthy growth.

What Does Molybdenum Do for Plants?

Molybdenum is a micronutrient that supports:

• Nitrogen conversion within the plant
• Enzyme activity related to nitrogen assimilation
• General metabolic efficiency

It’s particularly important for enzymes that convert nitrate to ammonium, the form of nitrogen plants use for building amino acids and proteins.

How Much Molybdenum Do Plants Need?

Not much—molybdenum is needed in ultra-small amounts, often listed at the bottom of fertiliser labels. Even so, its presence is essential, and deficiencies (while rare) can disrupt nitrogen processing.

“It’s one of the lowest percentage nutrients on fertiliser labels, but that doesn’t make it unimportant.” – Dr. Sharp

When Does it Become a Problem?

You’re unlikely to see deficiency in most hydroponic setups. However, problems may occur when:

• Soil or media pH is too low (acidic conditions reduce molybdenum availability)
• You’re using non-balanced fertilisers
• You’re growing in low-organic-matter soil

That said, more common issues like calcium or iron deficiencies will usually appear long before molybdenum becomes a limiting factor.

Signs of Deficiency (Not That You’ll Likely See Them)

Deficiency symptoms are so rare, they’re barely worth listing. In fact, listing them might lead growers down the wrong path, mistaking another nutrient issue (like copper or magnesium) for molybdenum deficiency.

Trust your system. If you’re using a quality fertiliser and monitoring your pH, molybdenum will take care of itself.

Should You Worry About it?

Not really. If you’re using a product like Gold Leaf or Liquid Gold, which includes a complete micronutrient profile, you’re already covered.

“I wouldn’t worry about it. I’ve never even seen a clear molybdenum deficiency symptom in practice.”

Final Thoughts: Small But Essential

Even though it doesn’t make headlines like nitrogen, potassium, or iron, it’s still a key player in plant metabolism. When every part of your nutrient mix is balanced, your plants thrive—and molybdenum quietly does its job in the background.

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