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In this blog, we’re focusing on a key macronutrient that often flies under the radar: phosphorus.
Essential for everything from DNA synthesis to root development, phosphorus plays a foundational role in plant health. Whether you’re growing leafy greens hydroponically or cultivating perennials outdoors, understanding how phosphorus works—and what can go wrong—is crucial.
Phosphorus is vital for all forms of life because it’s required for:
Without enough phosphorus, plants simply can’t function. ATP, for instance, is the cell’s “battery”—and it contains three phosphate groups. So without phosphorus, there is no energy for growth.
The most common signs of phosphorus deficiency include:
🔍 Important Note: Once purpling appears, the deficiency is already severe. You’ll need to correct it quickly to avoid long-term damage.
Even when phosphorus is present in your grow media, it can become unavailable to plants. Here’s why:
Alkaline environments cause phosphorus to bind with calcium, forming insoluble compounds (like calcium phosphate) that plants can’t absorb.
Over-application of CalMag or calcium-rich water sources can cause nutrient lockout, making phosphorus inaccessible.
Some one-part hydroponic fertilizers cause precipitation—where calcium and phosphorus settle into a sludge at the bottom of the tank. That sludge? It’s useless to your plants.
💡 Tip: Avoid fertilizers that form sediment. Products like Gold Leaf (or Liquid Gold in the UK) are formulated to prevent calcium-phosphorus lockout.
A common gardening phrase is “phosphoroots”—and for good reason.
Phosphorus is essential for early root development. It’s especially important for:
Think of it this way:
Beneficial fungi called mycorrhizae form symbiotic relationships with plant roots. Their primary job? Extracting phosphorus from the soil or substrate and delivering it to the plant.
They do this by:
🌱 In hydroponics, maintaining mycorrhizal colonies can dramatically improve phosphorus availability—especially in perennial systems.
A fun insider tip: you can often spot amateur fertilizer manufacturers by their spelling. The correct spelling is phosphorus, not “phosphorous.” While “phosphorous” is a real word (referring to a specific chemical form), it’s not interchangeable. Always check labels for accuracy—it’s a small sign of a trustworthy brand.
Phosphorus is the second most critical nutrient by volume, after nitrogen. It fuels everything from root formation to energy transfer and DNA replication. If you’re seeing poor root growth or purpling leaves, it’s time to take a closer look at your phosphorus supply and nutrient balance.
Balanced, high-quality products—like Liquid Gold—help ensure your plants get phosphorus in a form they can actually use, without the risk of lockout.
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