Hydroponic Plant Nutrition

The 17 essential elements — and why water beats soil at delivering them

Plants require carbon, hydrogen and oxygen from air and water, plus 14 mineral nutrients from solution: N, P, K, Ca, Mg, S (macros) and Fe, Mn, Zn, Cu, B, Mo, Cl, Ni (micros). In soil these are unevenly distributed, bound to minerals, and partly inaccessible. In hydroponics they are dissolved, ionised, and presented directly to the root surface at the EC and pH chosen by the grower.

EC and pH — the two dials that decide your yield

Electrical conductivity (EC) is a proxy for total dissolved salts. Leafy greens grow best at EC 1.0–1.6 mS/cm and pH 5.5–6.2; fruiting crops like tomato sit at EC 2.0–3.5 and pH 5.8–6.2. Outside these ranges, specific nutrient lockouts begin: iron at pH > 6.5, calcium and magnesium below pH 5.5, and ammonium toxicity at warm temperatures with high NH₄⁺ share.

Water savings backed by FAO field data

FAO and multiple peer-reviewed reviews report that closed-loop hydroponic systems consume 70–90 % less water than equivalent soil production, with simultaneous yield increases of 2–10× per square metre depending on crop and climate. The savings come from zero deep-percolation losses and ~95 % water-use efficiency at the root zone.

Why a 3-part nutrient line works

• MICRO: supplies Ca, Mg, Fe and all trace elements — the backbone every stage needs.
• GROW: nitrogen-led blend for vegetative leaf, stem and root development.
• BLOOM: phosphorus- and potassium-led blend for flowering, fruit set and ripening.
• Adjusting the ratio (not the total EC) is what shifts a plant between growth phases — this is the same logic that runs every Sonneveld-style greenhouse recipe.

“In a properly managed closed hydroponic system, water-use efficiency approaches 95 % and nutrient losses to the environment approach zero — a profile no soil-based system can match.”

— Sonneveld & Voogt, 2009