pH Scale
Explore how pH affects nutrient availability.
Explore your pH
Move the slider or enter your reading.
Where to measure
Enter your feed-solution pH: test the fully mixed nutrient solution in your tank or at the irrigation outlet, after adding nutrients. Check pH and EC daily with calibrated meters.
Growing in stonewool? Check the solution inside the block or slab separately using your substrate supplier’s sampling method. It can differ from the tank reading, so do not treat the range above as a root-zone target.
Preparing new blocks or slabs: Grodan specifies pH 5.5–6.5 for initial saturation. Follow the preparation instructions for your specific product. Ongoing feed targets depend on your crop, growth stage, and nutrient program.
Nutrient availability at 6.5
Availability means a nutrient can be accessed by roots—not how much a plant actually absorbs. These approximate bands are educational, not measured uptake rates or fertilizer recommendations.
Nutrients in a soilless system
A suitable pH supports a balanced nutrient solution, but crop and pH alone cannot predict individual nutrient absorption. Fertilizer composition, chelates, EC, and root-zone conditions matter. The soil nutrient ratings are hidden for this medium.
Check your nutrient supplier’s crop and substrate guidance. An in-range pH does not guarantee that every nutrient is present or available.
What your results mean
Move the slider or enter your pH reading to explore the guidance for your growing method. The green bands show the suggested ranges, and the vertical line marks your pH.
Use these results as a starting point. Your crop, growing medium, moisture, and nutrient levels also affect how well plants can use nutrients.
This tool shows 12 nutrients across pH 1–10. Below pH 4 or above pH 9, ratings aren’t shown because these conditions are too extreme for most crops.
The coco scale adapts Purdue’s soilless nutrient-availability chart. Move the slider to compare your root-zone pH with the published general substrate range. The rounded green bars show that same reference for the ten nutrients plotted by Purdue; they are not individual nutrient availability limits. Nutrient notes summarize the figure’s relative trends. The report does not provide exact coco-specific cutoffs or uptake percentages.
Root-zone reference: 5.4–6.2. This is Purdue’s general range for many greenhouse crops. Use a consistent coco sampling method; tank and runoff readings can differ from pH inside the medium.
Feeding reference: 5.5–6.2. CANNA Coco A & B recommends this range for mixed feed. Your crop and nutrient program may use a different target. Sulfur and molybdenum are not included in Purdue’s chart and are not assigned availability bands.
pH guide by crop
Find your crop below for a suggested pH range based on your selected growing method.
Showing: Soil
| Crop | Suggested soil pH |
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Need a pH meter?
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