pH and EC Management
pH and EC are the two numbers that matter most to your nutrient solution. Get these right and most feeding problems disappear.
Why pH Is Everything
Cannabis can only absorb nutrients within specific pH ranges. Outside these ranges, nutrients become chemically locked and unavailable even if they are physically present in your medium. Think of pH as a series of gates — at the wrong pH, the gates are closed regardless of how much nutrient you add. This is why pH management is non-negotiable.
Target pH Ranges
Soil: 6.0–7.0 (ideal 6.5). Coco coir: 5.5–6.5 (ideal 5.8–6.2). Hydroponics: 5.5–6.5 (ideal 5.8–6.0). Test the pH of your water after adding nutrients, before watering. Use pH Up (potassium hydroxide) or pH Down (phosphoric acid) to adjust. Always add small amounts — a little goes a long way.
EC — Feeding Strength
EC measures total dissolved solids in your water. Your tap water will have a baseline EC (typically 0.2–0.8 mS/cm). Add this to your target nutrient EC. Target total EC: seedlings 0.8–1.2, veg 1.2–2.0, flower 1.8–2.8. For soil grows, EC management is less critical than for hydro, but still useful for detecting overfeeding.
Watering Technique
Water until you get 10–20% runoff from the bottom of your pot. Test the EC and pH of this runoff water. Runoff pH tells you the actual pH at the root zone — important for soil grows. Runoff EC tells you if salts are building up (high runoff EC) or if the plant is hungry (runoff EC much lower than input).
Links go to Amazon. Cannapedia earns a small commission at no extra cost to you. We only recommend gear we consider genuinely good value.
Quick Tips
- Calibrate your pH meter weekly with calibration solution — pH meters drift and give false readings.
- pH Up and Down are caustic — handle carefully and store away from children.
- The ideal watering time is just after lights on when stomata are opening.