EC / PPM

EC gives you an overall indication of your nutrient solution’s strength by measuring dissolved salts—including those already in your water. It doesn’t tell you which nutrients are present or how much your plants absorb.

Why PPM readings can differ

Meters convert EC to an estimated PPM using either a 500 or 700 scale. The same solution at 2.0 EC (mS/cm) reads:

• 500 scale: 1,000 PPM
• 700 scale: 1,400 PPM

Always match your meter’s scale to the chart or feeding guide you’re using.

These are nutrient-solution readings, not soil, runoff, or substrate-extract targets.

Choose your crop and its current growth stage. Plants develop at different speeds, so this chart uses growth stages instead of fixed week numbers.

• Leafy greens, herbs, and cabbage-family crops: These are usually harvested before flowering. Any flowering ranges shown are for reference only.
• Microgreens: Only early growth stages apply, so later-stage ranges aren’t shown.

For consistent readings, keep your meter calibrated and use the same testing method each time. An EC reading within the suggested range doesn’t necessarily mean your plants have the right balance of nutrients.