Measuring and setting pH & EC correctly: the foundation of healthy plants

You feed to a plan and still the plant struggles? In nine out of ten cases it comes down to two values many beginners overlook: pH and EC. They decide whether your plant can take up nutrients at all. The good news: both are checked in seconds with inexpensive meters. This guide explains what is behind them and how to reliably get both into the green zone.

What is the pH value?

The pH value indicates how acidic or basic your nutrient solution is. The scale runs from 0 (very acidic) to 14 (very basic), with 7 being neutral. It is decisive for the plant because each nutrient can only be taken up by the roots within a certain pH window.

If the pH is off, the plant "starves" in the middle of a full pot: the nutrient is there but chemically unavailable. This phenomenon is called lockout and is one of the most common causes of supposed deficiencies.

What is the EC value?

EC stands for electrical conductivity and measures how many dissolved salts (i.e. nutrients) are in the water. Put simply: the EC value tells you how "strong" your nutrient solution is. It is usually given in mS/cm (some meters show ppm/TDS).

Important: even your tap water has a baseline EC. Measure it once before feeding and factor it in, otherwise you overfeed without noticing.

EC: follow the dosing, not fixed targets

Instead of chasing a fixed target EC, go by the dosing in the BudXXL feeding schedule (millilitres per litre). Your EC follows from that and typically rises from the vegetative to the full-flower phase; during the flush week it drops to the value of your plain water. Measure it only as a check, so it does not creep up unnoticed.

• ml/L
  dosing per schedule
• rises
  veg → full flower
• ~3 mS/cm
  rough upper limit
• measure
  as a check only

The matching nutrient amounts for these phases are broken down ready to use in the BudXXL feeding schedule.

How to measure correctly: step by step

1. Mix the nutrient solution completely. Stir in all nutrients first, then measure. Not before.
2. Measure EC. Note it as a check. If it climbs unusually high (towards 3 mS/cm), dilute a little with water.
3. Measure pH. Only afterwards, because nutrients change the pH value.
4. Set pH. Use pH- (lower) or pH+ (raise) to your medium's target range.
5. Maintain your meters. Calibrate the pH meter regularly and store the probe moist, otherwise the readings drift.

Setting pH with pH- and pH+

Always work drop by drop: add a small amount, stir, measure again, repeat. pH- in particular is highly concentrated, a few drops move a lot. Better to approach slowly than to overshoot and correct back.

Common mistakes

• Measured pH before feeding. Nutrients shift the value, so always set it last.
• Ignored the tap water EC. This leads to creeping overfeeding.
• Never calibrated the pH meter. Then you are measuring fantasy values.
• Treated a deficiency instead of checking pH. Often it is lockout, not a real deficiency.

What comes next

• Cannabis growing for beginners (the big overview)
• The BudXXL feeding schedule explained (dosage week by week)
• Spotting and fixing nutrient deficiencies (when it struggles despite correct values)

Matching products

• BudXXL CalMag→

Sources

• Veazie, P. et al. (2025): Impact of substrate pH and micronutrient fertility rates on Cannabis sativa. Agrosystems, Geosciences & Environment. doi.org/10.1002/agg2.70044
• Baas, R. & Wijnen, D. (2023): Salinity effects on yield and nutrient uptake in Cannabis sativa L. Acta Horticulturae 1377. doi.org/10.17660/ActaHortic.2023.1377.97

Legal note: The private cultivation of cannabis has been permitted in Germany for adults within the legally regulated framework since the Consumer Cannabis Act (CanG, 2024) (personal use, limited number of plants, no access for minors). This article is for information and does not replace legal advice.