Nitrate is the negatively charged ion NO3-, the dominant nitrogen form in mineral feeds and in aerated soil. Roots absorb it actively, store it in vacuoles and reduce it to ammonium inside the plant before building amino acids, a step that needs molybdenum.
In practice
Most cannabis feeds supply 80-100% of their nitrogen as nitrate, from calcium nitrate, potassium nitrate and magnesium nitrate. When roots take up nitrate they release hydroxide or bicarbonate to stay balanced, so a nitrate-heavy recirculating reservoir drifts up in pH over days. Growers counter that with a small ammonium fraction or acid.
Labels and lab reports may quote "nitrate" or "NO3-N". NO3-N counts only the nitrogen: 1 mg/L NO3-N = 4.43 mg/L NO3-. Always check which one a report means.
Don't confuse with
- Nitrite (NO2-): an intermediate, toxic at higher levels, not a feed form.
- Ammonium: the positively charged nitrogen form, which pushes pH down.
- Nitrogen: the element, counted the same whichever ion carries it.
Ammonium (NH4+) is the positively charged form of nitrogen; a small share stabilises root-zone pH, but too much reduces cannabis yield and quality.Molybdenum (Mo) is the micronutrient needed in the smallest amount; plants need it to convert nitrate into usable nitrogen.Calcium nitrate is the standard hydroponic calcium source, supplying about 19% calcium and 15.5% nitrogen, mostly as nitrate.Potassium nitrate (KNO3) is a soluble fertiliser salt supplying about 13% nitrogen as nitrate and 38% potassium, used in both veg and flower feeds.Magnesium nitrate supplies about 9.5% magnesium and 11% nitrogen as nitrate, and unlike Epsom salt it can share a concentrated stock with calcium nitrate.A recirculating (closed) system returns drained nutrient solution to the reservoir to be reused, saving water and nutrients but needing more monitoring and sanitation.pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.A COA (certificate of analysis) is a lab's signed report of what it measured in a specific sample, such as cannabinoids, terpenes, moisture and contaminants, with methods and limits.Nitrogen (N) is the macronutrient plants use most, built into proteins, chlorophyll and nucleic acids; it drives leaf and stem growth and is fully mobile.Nitric acid (HNO3) lowers pH while adding nitrate nitrogen; growers use it to neutralise hard-water alkalinity, often alongside or instead of phosphoric acid.
